pumpfundamentals : Messages : 191-220 of 498

#191

From: "farid" <bachik_syes@...>
Date: Thu Jan 5, 2012 9:33 am
Subject: minimmum flow line

hye there. i am a newbie here for pump design. just to know something that is it
any standard or parameter or guidline in order to install minimum flow line for
pump especially for fire water pump? if any one can share, appriciate if can
reply. is it the design still the same for the ordinary pump? thank you

Reply | Messages in this Topic (18)

#192

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Thu Jan 5, 2012 10:07 am
Subject: Re: minimmum flow line

sl_abh

Send Email

Dear Mr. Farid,

Since for fighting fire, one needs to get maximum flow available from a pump, one would usually run the pumps with maximum flow. So, installing minimum flow line should prove redundant for fire-fighting pumps.

Regards,
ESSEL

On 5 January 2012 15:03, farid <bachik_syes@...> wrote:

hye there. i am a newbie here for pump design. just to know something that is it any standard or parameter or guidline in order to install minimum flow line for pump especially for fire water pump? if any one can share, appriciate if can reply. is it the design still the same for the ordinary pump? thank you

--
Cordially, S. L. Abhyankar
सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#193

From: farid farid <bachik_syes@...>
Date: Fri Jan 6, 2012 12:50 am
Subject: Re: minimmum flow line

bachik_syes

Send Email

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

Reply | Messages in this Topic (18)

#194

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Fri Jan 6, 2012 6:23 am
Subject: Re: Re: minimmum flow line

sl_abh

Send Email

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !
Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it.
Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.
Total head has two parts (1) static head (2) friction head
If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head
One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.
Static head is usually clear from the plant layout.
Friction head needs to be calculated from reference charts, tables, etc.
One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

Reply | Messages in this Topic (18)

#195

From: Jacques Chaurette <jacqueschaurette@...>
Date: Fri Jan 6, 2012 11:22 am
Subject: RE: Re: minimmum flow line

jacqueschaurette@...

Send Email

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !
Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.
Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.
Total head has two parts (1) static head (2) friction head
If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head
One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.
Static head is usually clear from the plant layout.
Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.
One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

Reply | Messages in this Topic (18)

#196

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Fri Jan 6, 2012 6:01 pm
Subject: Re: Re: minimmum flow line

sl_abh

Send Email

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

--
Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#197

From: jacqueschaurette@...
Date: Fri Jan 6, 2012 7:07 pm
Subject: Re : Re: Re: minimmum flow line

jacqueschaurette@...

Send Email

Dear SLA, thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques

----- Message d'origine -----
De: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Vendredi, 6 Janvier 2012, 1:01 pm
Objet: Re: [pumpfundamentals] Re: minimmum flow line
À: Jacques Chaurette <jacqueschaurette@...>
Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

--
Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

--
Cordially, S. L. Abhyankar
सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#198

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Sat Jan 7, 2012 5:38 am
Subject: Re: Re : Re: Re: minimmum flow line

sl_abh

Send Email

Dear Mr. Jacques,

As you have observed, the problem seems to be with the pressure setting, how much low pressure and how much high pressure for starting and stopping of jockey pump. And looks like O&M manuals need to clarify what to do when the jockey pumps starts and stops too frequently. As you have observed, there would be heavy leakage in the system, which would cause that.

Also the difference in the low and high pressure settings should be good enough. By that also the frequency of starting and stopping will not be too much.

You have made a good point that sprinklers would need line to be pressurized.

When I made the point of line should be full and not necessarily under pressure, I had in mind the fire-fighting system drowsing fire by water from hoses. Such system may not need line to be under pressure. Pumps would develop needed pressure.

However, sprinklers would certainly need.

So whether line should be under pressure or not, would depend on the type of fire-fighting system. Am I right ?

Regards,
SLA

On 7 January 2012 00:37, <jacqueschaurette@...> wrote:

Dear SLA, thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques

----- Message d'origine -----
De: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Vendredi, 6 Janvier 2012, 1:01 pm
Objet: Re: [pumpfundamentals] Re: minimmum flow line
À: Jacques Chaurette <jacqueschaurette@...>
Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

--
Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

--
Cordially, S. L. Abhyankar
सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#199

From: Jacques Chaurette <jacqueschaurette@...>
Date: Sat Jan 7, 2012 12:45 pm
Subject: RE: Re : Re: Re: minimmum flow line

jacqueschaurette@...

Send Email

Indeed you are right.

Jacques

From: S. L. Abhyankar [mailto:sl.abhyankar@...]
Sent: Saturday, January 07, 2012 12:38 AM
To: jchaurette@...; jacqueschaurette@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

On 7 January 2012 00:37, <jacqueschaurette@...> wrote:

cheers,

Happy new year

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

--
Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

--
Cordially, S. L. Abhyankar
सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#200

From: farid farid <bachik_syes@...>
Date: Mon Jan 16, 2012 2:40 am
Subject: Re: Re : Re: Re: minimmum flow line

bachik_syes

Send Email

first of all, i would like to thanks to both SLA and JC for you response abount pump. next i do have the other question and sorry if my question is kind of simple/silly question since i am a newbie im pump technology.

my questions are

1. I dont know what is actually "frequency" and "pole" that relate to the pump. i get this from JGC (japan standard). refer attach file for further detail about frequency and pole. this is used when we want to specify the rotational speed of the pump.

2. i make a calculation for NPSHa and suppose i need to compare with NPSHr. but letsay i dont have the NPSHr value (since the pump is very old 1975) and the pump curve is not available, then how do i estimate/ calculate the NPSHr? can i use equation

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

frm: "jacqueschaurette@..." <jacqueschaurette@...>
To: pumpfundamentals@yahoogroups.com
Cc: bachik_syes@...; pumpfundamentals@yahoogroups.com
Sent: Saturday, January 7, 2012 3:07 AM
Subject: Re : Re: [pumpfundamentals] Re: minimmum flow line

cheers,

Happy new year

Jacques ----- Message d'origine -----De: "S. L. Abhyankar" <sl.abhyankar@...>Date: Vendredi, 6 Janvier 2012, 1:01 pmObjet: Re: [pumpfundamentals] Re: minimmum flow lineÀ: Jacques Chaurette <jacqueschaurette@...>Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.comhttp://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.comhttp://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#201

From: Jacques Chaurette <jacqueschaurette@...>
Date: Mon Jan 16, 2012 12:13 pm
Subject: RE: Re : Re: Re: minimmum flow line

jacqueschaurette@...

Send Email

Hello Farid, the no. of poles determines the speed of the motor, the speed of the motor is also determined by the frequency, 60 hz in North America, 50 hz in many other places, Europe for example.

Where does the equation for NPSHR come from?

Jacques Chaurette

http://www.pumpfundamentals.com

Learn about pumps

http://www.chordsandguitar.com

Easy access, FREE, beautiful guitar chords

From: farid farid [mailto:bachik_syes@...]
Sent: Sunday, January 15, 2012 9:40 PM
To: jacqueschaurette@...; pumpfundamentals@yahoogroups.com
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

my questions are

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

cheers,

Happy new year

Jacques ----- Message d'origine -----De: "S. L. Abhyankar" <sl.abhyankar@...>Date: Vendredi, 6 Janvier 2012, 1:01 pmObjet: Re: [pumpfundamentals] Re: minimmum flow lineÀ: Jacques Chaurette <jacqueschaurette@...>Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#202

From: farid farid <bachik_syes@...>
Date: Tue Jan 17, 2012 12:19 am
Subject: Re: Re : Re: Re: minimmum flow line

bachik_syes

Send Email

thanks JC for the answer..it is from JGC corporation. i dont know what JGC means. its like JAPAN standard. like Shell, they have DEP (design engineering practice) and Petronas has PTS (petronas technical standard). this standard will specify how to design, based on what etc..refer attach pic for the equation and example. and i do have 3 more questions to you

1. why we must have reducer at the suction? is it to increase the velocity of the fluid? and why we must have enlarger at the discharge site?

2. i've calculate one of the NPSHa of a pump and the value is very low.(about 0.3 m) and i.m so worried that the pump will cavitate. but the pump vendor said dont worry, as long as the fluid full in the pipe, it would be ok. is it true? for me, whether the fluid is full or not, if the pressure drop approach to the vapor pressure, the fluid will start to vaporise no matter full or not right?

3.can i know what is pump flushing line?

thank you so much for spending your time answering my question. appriciate also SLA can response to my question

rgds

MFK

From: Jacques Chaurette <jacqueschaurette@...>
To: 'farid farid' <bachik_syes@...>; pumpfundamentals@yahoogroups.com
Sent: Monday, January 16, 2012 8:13 PM
Subject: RE: Re : Re: [pumpfundamentals] Re: minimmum flow line

Hello Farid, the no. of poles determines the speed of the motor, the speed of the motor is also determined by the frequency, 60 hz in North America, 50 hz in many other places, Europe for example.

Where does the equation for NPSHR come from?

Jacques Chaurette

http://www.pumpfundamentals.com

Learn about pumps

http://www.chordsandguitar.com

Easy access, FREE, beautiful guitar chords

my questions are

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

Dear SLA , thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques ----- Message d'origine ----- De: "S. L. Abhyankar" <sl.abhyankar@...> Date: Vendredi, 6 Janvier 2012, 1:01 pm Objet: Re: [pumpfundamentals] Re: minimmum flow line À: Jacques Chaurette <jacqueschaurette@...> Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।" http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/ http://slez-musings.blogspot.com स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365 चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankar सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।" http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/ http://slez-musings.blogspot.com स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365 चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#203

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Tue Jan 17, 2012 8:36 am
Subject: Re: Re : Re: Re: minimmum flow line

sl_abh

Send Email

Dear Mr. Farid,

As clarified by Mr. Jacques, number of poles and frequency determine the speed of the motor. The formula is

Speed of motor = 120 * f / p,

where f = frequency in Hz and
p = number of poles.

For example, 50 Hz supply and 2-pole motor, speed = 3000 rpm. This speed is the synchronous speed. Induction motors will have a slip. This will be dictated by the design of the motor, most prominently by the air-gap between stator and rotor. If slip is 2 %, actual speed will be 0.98 * 3000 = 2940 rpm. That is why you find all those odd values in the tabulation.

I am also curious to know the source of your equation for NPSHr !

Default value of Sn (Suction specific speed) as 11000 and flow in m3/hr seems to be an odd combination. Value such as 11000 will mostly be in US units and flow in m3/hr is in metric units. I am getting skeptical about the equation !

Regards,
SLA

On 16 January 2012 17:43, Jacques Chaurette <jacqueschaurette@...> wrote:

Hello Farid, the no. of poles determines the speed of the motor, the speed of the motor is also determined by the frequency, 60 hz in North America, 50 hz in many other places, Europe for example.

Where does the equation for NPSHR come from?

Jacques Chaurette

http://www.pumpfundamentals.com

Learn about pumps

http://www.chordsandguitar.com

Easy access, FREE, beautiful guitar chords

From: farid farid [mailto:bachik_syes@...]
Sent: Sunday, January 15, 2012 9:40 PM
To: jacqueschaurette@...; pumpfundamentals@yahoogroups.com
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

first of all, i would like to thanks to both SLA and JC for you response abount pump. next i do have the other question and sorry if my question is kind of simple/silly question since i am a newbie im pump technology.

my questions are

1. I dont know what is actually "frequency" and "pole" that relate to the pump. i get this from JGC (japan standard). refer attach file for further detail about frequency and pole. this is used when we want to specify the rotational speed of the pump.

2. i make a calculation for NPSHa and suppose i need to compare with NPSHr. but letsay i dont have the NPSHr value (since the pump is very old 1975) and the pump curve is not available, then how do i estimate/ calculate the NPSHr? can i use equation

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

frm: "jacqueschaurette@..." <jacqueschaurette@...>
To: pumpfundamentals@yahoogroups.com
Cc: bachik_syes@...; pumpfundamentals@yahoogroups.com
Sent: Saturday, January 7, 2012 3:07 AM
Subject: Re : Re: [pumpfundamentals] Re: minimmum flow line

Dear SLA, thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques ----- Message d'origine -----De: "S. L. Abhyankar" <sl.abhyankar@...>Date: Vendredi, 6 Janvier 2012, 1:01 pmObjet: Re: [pumpfundamentals] Re: minimmum flow lineÀ: Jacques Chaurette <jacqueschaurette@...>Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#204

From: Jacques Chaurette <jacqueschaurette@...>
Date: Tue Jan 17, 2012 9:28 am
Subject: RE: Re : Re: Re: minimmum flow line

jacqueschaurette@...

Send Email

See answers in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of farid farid
Sent: Monday, January 16, 2012 7:20 PM
To: pumpfundamentals@yahoogroups.com
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

why we must have reducer at the suction? is it to increase the velocity of the fluid? and why we must have enlarger at the discharge site?

Typically we want a nice smooth flow with minimal turbulence at the pump suction (3-6 ft/s) this often results in having to put a reducer at the pump suction. On the discharge favored velocities are 9-12 ft/s. this sometimes results in having to enlarge the line on the discharge side. You can use a smaller line but at the cost of higher friction loss.

i've calculate one of the NPSHa of a pump and the value is very low.(about 0.3 m) and i.m so worried that the pump will cavitate. but the pump vendor said dont worry, as long as the fluid full in the pipe, it would be ok. is it true? for me, whether the fluid is full or not, if the pressure drop approach to the vapor pressure, the fluid will start to vaporise no matter full or not right?

If your calculations are correct this is indeed very low, for most application with a positive suction head you should be in the 25-30 ft absolute range. I disagree with the vendor this will cause cavitation as you say.

3.can i know what is pump flushing line?

I am not sure what you are referring to, certain types of seals require a flush connection.

thank you so much for spending your time answering my question. appriciate also SLA can response to my question

rgds

MFK

Hello Farid, the no. of poles determines the speed of the motor, the speed of the motor is also determined by the frequency, 60 hz in North America, 50 hz in many other places, Europe for example.

Where does the equation for NPSHR come from?

Jacques Chaurette

http://www.pumpfundamentals.com

Learn about pumps

http://www.chordsandguitar.com

Easy access, FREE, beautiful guitar chords

my questions are

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

Dear SLA , thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques ----- Message d'origine ----- De: "S. L. Abhyankar" <sl.abhyankar@...> Date: Vendredi, 6 Janvier 2012, 1:01 pm Objet: Re: [pumpfundamentals] Re: minimmum flow line À: Jacques Chaurette <jacqueschaurette@...> Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.
Total head has two parts (1) static head (2) friction head
If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head
One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.
Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।" http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/ http://slez-musings.blogspot.com स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365 चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankar सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।" http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/ http://slez-musings.blogspot.com स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365 चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#205

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Tue Jan 17, 2012 10:41 am
Subject: Re: Re : Re: Re: minimmum flow line

sl_abh

Send Email

Dear Mr. Farid,

I did google-search for JGC Corporation ! It seems to be an Engineering Company in Japan (established 1928 !).

Many engineering companies do have engineering manuals for internal use, which in course of time are referred to like textbooks. For example I have with me a book "Planing of Centrifugal Pumping Plants" from SULZER. The book from JGC with you seems to be similar.

You are getting low value of NPSH with Sn as 11000. I have seen in older editions of Hydraulic Institute Standards value of Sn taken as 8500. If you take this value, you will get higher value, because, in the equation, Sn is in the denominator.

In fact I am surprised that you get a value as 0.3 m even when there is a constant "+ 0.6" in the equation. I suspect there is some mistake in your calculations.

I find some incongruent calculations illustrated in your "Capture 2" image, especially at Eq. (8) for Specific Speed. The pump selected is double-stage. Then per stage head would be 296/2 = 148m for calculating specific speed. Also the equation for specific speed needs Q to be in m3/s. Given Q is 141 m3/hr. Then calculating specific speed should be Ns = (2960)*(141)^0.5/60/(148)^0.75. The illustration shows (2960)*(141/60)^0.5/(296)^0.75. The divisor 60 needs to be outside the paranthesis.

But the equation for NPSHr interests me. I am getting tempted to find some example-results.

Please check back your calculations as well.

Regards,
SLA

On 17 January 2012 14:06, S. L. Abhyankar <sl.abhyankar@...> wrote:

Dear Mr. Farid,

As clarified by Mr. Jacques, number of poles and frequency determine the speed of the motor. The formula is

Speed of motor = 120 * f / p,

where f = frequency in Hz and
p = number of poles.

For example, 50 Hz supply and 2-pole motor, speed = 3000 rpm. This speed is the synchronous speed. Induction motors will have a slip. This will be dictated by the design of the motor, most prominently by the air-gap between stator and rotor. If slip is 2 %, actual speed will be 0.98 * 3000 = 2940 rpm. That is why you find all those odd values in the tabulation.

I am also curious to know the source of your equation for NPSHr !

Default value of Sn (Suction specific speed) as 11000 and flow in m3/hr seems to be an odd combination. Value such as 11000 will mostly be in US units and flow in m3/hr is in metric units. I am getting skeptical about the equation !

Regards,
SLA

On 16 January 2012 17:43, Jacques Chaurette <jacqueschaurette@...> wrote:

Hello Farid, the no. of poles determines the speed of the motor, the speed of the motor is also determined by the frequency, 60 hz in North America, 50 hz in many other places, Europe for example.

Where does the equation for NPSHR come from?

Jacques Chaurette

http://www.pumpfundamentals.com

Learn about pumps

http://www.chordsandguitar.com

Easy access, FREE, beautiful guitar chords

From: farid farid [mailto:bachik_syes@...]
Sent: Sunday, January 15, 2012 9:40 PM
To: jacqueschaurette@...; pumpfundamentals@yahoogroups.com
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

first of all, i would like to thanks to both SLA and JC for you response abount pump. next i do have the other question and sorry if my question is kind of simple/silly question since i am a newbie im pump technology.

my questions are

1. I dont know what is actually "frequency" and "pole" that relate to the pump. i get this from JGC (japan standard). refer attach file for further detail about frequency and pole. this is used when we want to specify the rotational speed of the pump.

2. i make a calculation for NPSHa and suppose i need to compare with NPSHr. but letsay i dont have the NPSHr value (since the pump is very old 1975) and the pump curve is not available, then how do i estimate/ calculate the NPSHr? can i use equation

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

frm: "jacqueschaurette@..." <jacqueschaurette@...>
To: pumpfundamentals@yahoogroups.com
Cc: bachik_syes@...; pumpfundamentals@yahoogroups.com
Sent: Saturday, January 7, 2012 3:07 AM
Subject: Re : Re: [pumpfundamentals] Re: minimmum flow line

Dear SLA, thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques ----- Message d'origine -----De: "S. L. Abhyankar" <sl.abhyankar@...>Date: Vendredi, 6 Janvier 2012, 1:01 pmObjet: Re: [pumpfundamentals] Re: minimmum flow lineÀ: Jacques Chaurette <jacqueschaurette@...>Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

--
Cordially, S. L. Abhyankar
सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com

स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#206

From: "Jacques" <jchaurette@...>
Date: Tue Jan 17, 2012 8:34 pm
Subject: Re : Re: Re: minimmum flow line

jchaurette

Send Email

Dear Farid, I checked with Terry Henshaw, he is a pump specialist that writes
frequently in the Pump & System magazine (www.pump-zone.com). He oftens presents
quite complicated equations related to pump design and performance.

He recommends to use the formula for Suction speciifc speed and assume a value
of 7500 for Ns which is about what a typical single suction industrial volute
pump should run at. This will give you a good estimate for NPSHR.

Cheers,

Jacques

--- In pumpfundamentals@yahoogroups.com, "S. L. Abhyankar" <sl.abhyankar@...>
wrote:
>
> Dear Mr. Farid,
>
> I did google-search for JGC Corporation ! It seems to be an Engineering
> Company in Japan (established 1928 !).
>
> Many engineering companies do have engineering manuals for internal use,
> which in course of time are referred to like textbooks. For example I have
> with me a book "Planing of Centrifugal Pumping Plants" from SULZER. The
> book from JGC with you seems to be similar.
>
> You are getting low value of NPSH with Sn as 11000. I have seen in older
> editions of Hydraulic Institute Standards value of Sn taken as 8500. If you
> take this value, you will get higher value, because, in the equation, Sn is
> in the denominator.
>
> In fact I am surprised that you get a value as 0.3 m even when there is a
> constant "+ 0.6" in the equation. *I suspect there is some mistake in your
> calculations.*
>
> I find some incongruent  calculations illustrated in your "Capture 2"
> image, especially at Eq. (8) for Specific Speed. The pump selected is
> double-stage. Then per stage head would be 296/2 = 148m for calculating
> specific speed. Also the equation for specific speed needs Q to be in m3/s.
> Given Q is 141 m3/hr. Then calculating specific speed should be Ns =
> (2960)*(141)^0.5/60/(148)^0.75. The illustration shows
> (2960)*(141/60)^0.5/(296)^0.75. The divisor 60 needs to be outside the
> paranthesis.
>
> But the equation for NPSHr interests me. I am getting tempted to find some
> example-results.
>
> Please check back your calculations as well.
>
> Regards,
> SLA
>
>
> On 17 January 2012 14:06, S. L. Abhyankar <sl.abhyankar@...> wrote:
>
> > Dear Mr. Farid,
> >
> > As clarified by Mr. Jacques, number of poles and frequency determine the
> > speed of the motor. The formula is
> >
> > Speed of motor = 120 * f / p,
> >
> > where f = frequency in Hz and
> > p = number of poles.
> >
> > For example, 50 Hz supply and 2-pole motor, speed = 3000 rpm. This speed
> > is the synchronous speed. Induction motors will have a slip. This will be
> > dictated by the design of the motor, most prominently by the air-gap
> > between stator and rotor. If slip is 2 %, actual speed will be 0.98 * 3000
> > = 2940 rpm. That is why you find all those odd values in the tabulation.
> >
> > I am also curious to know the source of your equation for NPSHr !
> >
> > Default value of Sn (Suction specific speed) as 11000 and flow in m3/hr
> > seems to be an odd combination. Value such as 11000 will mostly be in US
> > units and flow in m3/hr is in metric units. I am getting skeptical about
> > the equation !
> >
> > Regards,
> > SLA
> >
> >
> > On 16 January 2012 17:43, Jacques Chaurette <jacqueschaurette@...
> > > wrote:
> >
> >> **
> >>
> >>
> >>  Hello Farid, the no. of poles determines the speed of the motor, the
> >> speed of the motor is also determined by the frequency, 60 hz in North
> >> America, 50 hz in many other places, Europe for example.****
> >>
> >> ** **
> >>
> >> Where does the equation for NPSHR come from?****
> >>
> >> ** **
> >>
> >> Jacques Chaurette****
> >>
> >> http://www.pumpfundamentals.com****
> >>
> >> Learn about pumps****
> >>
> >> http://www.chordsandguitar.com****
> >>
> >> Easy access, FREE, beautiful guitar chords****
> >>   ------------------------------
> >>
> >> *From:* farid farid [mailto:bachik_syes@...]
> >> *Sent:* Sunday, January 15, 2012 9:40 PM
> >> *To:* jacqueschaurette@...; pumpfundamentals@yahoogroups.com
> >> *Subject:* Re: Re : Re: [pumpfundamentals] Re: minimmum flow line****
> >>
> >> ** **
> >>
> >> first of all, i would like to thanks to both **SLA** and JC for you
> >> response abount pump. next i do have the other question and sorry if my
> >> question is kind of simple/silly question since i am a newbie im pump
> >> technology.****
> >>
> >>  ****
> >>
> >> my questions are****
> >>
> >>  ****
> >>
> >> 1. I dont know what is actually "frequency" and "pole" that relate to the
> >> pump. i get this from JGC (japan standard). refer attach file for further
> >> detail about frequency and pole. this is used when we want to specify the
> >> rotational speed of the pump.****
> >>
> >>  ****
> >>
> >> 2. i make a calculation for NPSHa and suppose i need to compare with
> >> NPSHr. but letsay i dont have the NPSHr value (since the pump is very old
> >> 1975) and the pump curve is not available, then how do i estimate/
> >> calculate the NPSHr? can i use equation ****
> >>
> >>  ****
> >>
> >> NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6****
> >>
> >>  ****
> >>
> >> where:****
> >>
> >> N=speed of rotation (RPM)****
> >>
> >> Sn=suction specific speed (default=11000)****
> >>
> >> Qd= rated flowrate (m3/h****
> >>
> >> i think thats all..appriciate if can answer my question.****
> >>
> >> rgds****
> >>
> >> MFK****
> >>
> >>  ****
> >>
> >>  fr*m:* "jacqueschaurette@..." <jacqueschaurette@...>
> >> *To:* pumpfundamentals@yahoogroups.com
> >> *Cc:* bachik_syes@...; pumpfundamentals@yahoogroups.com
> >> *Sent:* Saturday, January 7, 2012 3:07 AM
> >> *Subject:* Re : Re: [pumpfundamentals] Re: minimmum flow line
> >>   ****
> >>  **
> >>
> >> Dear **SLA**, thanks once again for your valuable input. Unfortunately I
> >> disagree, the line must remain under pressure to garantee instant coverage
> >> of water from the sprinkler(s) head(s) in case of fire. I don`t know why
> >> the jockey pumps are breaking, it should be set to start at a given low
> >> pressure and stop at a set high pressure with a reasonable dead zone. The
> >> pump will probably run for no more than a few minutes and stop on high
> >> pressure. If it stops and starts too often there is a serious leakage in
> >> the system that must be fixed.****
> >>
> >>  ****
> >>
> >> cheers,****
> >>
> >>  ****
> >>
> >> Happy new year****
> >>
> >>  ****
> >>
> >> Jacques ****----- Message d'origine -----**De: "S. L. Abhyankar" <
> >> sl.abhyankar@...>**Date: Vendredi, 6 Janvier 2012, 1:01 pm**Objet:
> >> Re: [pumpfundamentals] Re: minimmum flow line**À: Jacques Chaurette <
> >> jacqueschaurette@...>**Cc: bachik_syes@...,
> >> pumpfundamentals@yahoogroups.com****
> >> **
> >> **
> >>
> >>
> >>
> >> Dear Mr. Jacques Chaurette,
> >>
> >> Both of us have passion to look into problems on pumping, right ? It is
> >> that passion, which has motivated you to start this group ! I appreciate
> >> that very much.
> >>
> >> On another group, there was a post of repetitive failure (breakage !) of
> >> the shaft of a jockey pump. I guess, just to maintain the line pressure to
> >> take care of leakage, the jockey pump would keep running, even if the flow
> >> being pumped is too small, the leakage being small. Jockey pump had a
> >> pressure-switch control set at 15.4 bar whereas main pump rating was 12
> >> bar. These pressure-settings seem to be unduly high. Pressure-switch
> >> setting of 12.5 bar for the jockey pump should be good enough and at that
> >> pressure the jockey pump would be safely away from safe minimum flow. Then
> >> shaft-failures would not happen.
> >>
> >> Alternatively, instead of pressure setting one could explore using level
> >> control, to ensure that the line is full at the topmost point. If the level
> >> goes down by 5 m or so, that event should activate the jockey pump. Pump
> >> should get cut off when topmost level is reached. That is what I meant by
> >> "line should remain charged does not mean it should be under pressure."
> >>
> >> Regards,
> >> **SLA******
> >>
> >> On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...>
> >> wrote:** ****
> >>
> >>   ****
> >>
> >> Thank you **SLA** for these great answers and especially for taking the
> >> time. I would however offer the following corrections in red.****
> >>
> >>  ****
> >>
> >> Jacques ****
> >>
> >> *From:* pumpfundamentals@yahoogroups.com [mailto:
> >> pumpfundamentals@yahoogroups.com] *On Behalf Of *S. L. Abhyankar
> >> *Sent:* Friday, January 06, 2012 1:23 AM
> >> *To:* bachik_syes@...
> >> *Cc:* pumpfundamentals@yahoogroups.com
> >> *Subject:* Re: [pumpfundamentals] Re: minimmum flow line****
> >>
> >>  ****
> >>
> >>   ****
> >>
> >>    1. Can i know what is shut off pressure?****
> >>
> >>
> >>     - "Shut off pressure" refers to the pressure, when the discharge
> >>       valve is 'shut off'. Usually this is the maximum pressure the pump
will
> >>       develop. Standards for fire-fighting pump do not desire shut-off
pressure
> >>       (head) to be higher than 1.2 times of rated head. See NFPA 20 for
more
> >>       details ****
> >>
> >>
> >>    1. can pump running when discharge valve closed for a long period of
> >>    time i.e 1 day?****
> >>
> >>
> >>     - Pump running with discharge valve closed even for 5 minutes will
> >>       be risky !****
> >>
> >>
> >>     - Normally lines of fire-fighting systems are expected to stay fully
> >>       charged. But 'staying charged' does not mean that the line should be
under
> >>       pressure. It should be full. That is it. *In this type of system
> >>       the line must remain under pressure, because on big systems there are
> >>       always small leaks, a jockey pump (small pump) is used to keep the
system
> >>       pressurized.*****
> >>
> >>
> >>     - Usually the non-return valve on the discharge pipe will ensure
> >>       that water pumped by the pump when it is running will stay in the
pipeline
> >>       even after the pump is shut down. That helps the line to stay
charged.
> >>       ****
> >>
> >>
> >>    1. how we decide the right pump for that system? ****
> >>
> >>
> >>     - Two main parameters for selecting a pump are required flow-rate
> >>       and total head. Both are to be decided by the user according to the
system.
> >>       ****
> >>       - Total head has two parts (1) static head (2) friction head****
> >>       - If pump has to discharge into a pressurized vessel, e.g. boiler
> >>       drum, the pressure is to be converted into equivalent static head and
to be
> >>       added to the part (1) static head****
> >>       - One needs to add velocity head if discharge pipe size is smaller
> >>       than suction pipe size. But one can add 1 m for that, which is more
than
> >>       enough.****
> >>       - Static head is usually clear from the plant layout. ****
> >>
> >>
> >>     - Friction head needs to be calculated from reference charts,
> >>       tables, etc. *For these types of systems, the Hazen-Williams
> >>       friction formula must be used because the NFPA stipulates that it be
used.
> >>       *****
> >>
> >>
> >>     - One needs to consider "equivalent lengths" of various fittings and
> >>       valves****
> >>
> >>   Regards,
> >> **SLA**
> >>
> >> ****
> >>
> >> On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:****
> >>
> >>   ****
> >>
> >> i do have 3 questions****
> >>
> >>  ****
> >>
> >> 1. can i know what is shut off pressure?****
> >>
> >>  from my understanding, shut off pressure is the the higest pressure that
> >> can be produced by a pump and this happened at zero flow i.e. control valve
> >> closed at discharge line. so when pump running during discharge valve
> >> closed, the pressure builed up in the pipe line until a maximum pressure
> >> and this maximum pressure is shut off pressure. am i right? ****
> >>
> >>  ****
> >>
> >> 2. can pump running when discharge valve closed for a long period of time
> >> i.e 1 day? or is this will make the pump damage? from my knowledge, in the
> >> pipeline usually they have pressure transmitter which can detect high
> >> pressure in pipeline and will trip the pump once the pressure exceed the
> >> level. hope can correct me if i am wrong.****
> >>
> >>  ****
> >>
> >> 3. in order to size a pump, we need to know the total head of the system
> >> which is discharge head - suction head. then we get the total head. then
> >> how we decide the right pump for that system? ****
> >>
> >>  ****
> >>
> >> appriciate if can answer my questions as i am very interested in pump=)**
> >> **
> >>
> >>  ****
> >>
> >> thank you ****
> >>
> >>
> >>
> >> ****
> >>  **
> >>
> >> -- **Cordially, S. L. Abhyankar****
> >> **
> >>
> >> सस्नेहम्,
अभ्यंकरकुलोत्पन्नः श्रीपादः
| "श्रीपतेः पदयुगं स्मरणीयम्
।"**
> >> http://slabhyankar.wordpress.com <http://slabhyankar.wordpress.com/>**
> >>
http://study1geetaa2sanskrit.wordpress.com/<http://study1geetaa2sanskrit.wordpre\
ss.com/>
> >> **http://slez-musings.blogspot.com <http://slez-musings.blogspot.com/>**
> >> स्थापित-दूरभाष-क्रमाङ्कः +91 22
2849 5365**चलितभाष-क्रमाङ्कः +91 9757 21
> >> 5527****
> >> **
> >>      ********
> >>
> >> ******-- **Cordially, S. L. Abhyankar**सस्नेहम्,
अभ्यंकरकुलोत्पन्नः
> >> श्रीपादः | "श्रीपतेः पदयुगं
स्मरणीयम् ।"**
> >> http://slabhyankar.wordpress.com <http://slabhyankar.wordpress.com/>**
> >>
http://study1geetaa2sanskrit.wordpress.com/<http://study1geetaa2sanskrit.wordpre\
ss.com/>
> >> **http://slez-musings.blogspot.com <http://slez-musings.blogspot.com/>**
> >> स्थापित-दूरभाष-क्रमाङ्कः +91 22
2849 5365**चलितभाष-क्रमाङ्कः +91 9757 21
> >> 5527************ ****
> >>  ****
> >>
> >>
> >>
> >
> >
> >
> > --
> > Cordially, S. L. Abhyankar
> > सस्नेहम्,
अभ्यंकरकुलोत्पन्नः श्रीपादः
| "श्रीपतेः पदयुगं स्मरणीयम् ।"
> > http://slabhyankar.wordpress.com
> > http://study1geetaa2sanskrit.wordpress.com/
> > http://slez-musings.blogspot.com
> > स्थापित-दूरभाष-क्रमाङ्कः +91 22
2849 5365
> > चलितभाष-क्रमाङ्कः +91 9757 21 5527
> >
> >
> >
> >
> >
> >
>
>
> --
> Cordially, S. L. Abhyankar
> सस्नेहम्,
अभ्यंकरकुलोत्पन्नः श्रीपादः
| "श्रीपतेः पदयुगं स्मरणीयम् ।"
> http://slabhyankar.wordpress.com
> http://study1geetaa2sanskrit.wordpress.com/
> http://slez-musings.blogspot.com
> स्थापित-दूरभाष-क्रमाङ्कः +91 22
2849 5365
> चलितभाष-क्रमाङ्कः +91 9757 21 5527
>

Reply | Messages in this Topic (18)

#207

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Wed Jan 18, 2012 5:40 pm
Subject: Re: Re : Re: Re: minimmum flow line

sl_abh

Send Email

Dear Farid,

I read both - your message below and also latest reply from Mr. Jacques.

But I would first respond to your message below.

You have mentioned right in the first line "...NPSHa of the pump..". NPSHa is of the system, not of the pump. NPSHr is of the pump. And it is a rule that NPSHa > NPSHr.

Your senior saying that the pump vendor would take care of it is not wrong, only if the pump is designed and constructed that way. I myself designed a pump for LPG bottling plant, even when the purchase specification said, "NPSHa = 0" ! But it was a special design, special that NPSHr + margin was in-built in pump design by putting the pump assembly in a can so that the suction impeller gets adequate NPSHa. It was no magic that I did. It is common for pumps in critical applications as LPG or condensate extraction are built this way. The vendor has to be knowledgeable and competent.

Your senior is not right in thinking that a pump with flooded suction will not suffer cavitation-damage. I attach herewith a photo of an impeller where every blade of the impeller has metal dug out and at an almost average diameter on all blades. I got this photo when I was invited by my friend Mr. Sudhir Kale in Jakarta. He is Vice President Operations in a steel mill, Pt. Jakarta Cakratunggal Steel Mills.

The impeller was from a pump in their cooling water system, where the suction sump has water about 1.5 m above pump's suction. Yet the impeller was suffering severe cavitation damage.

There was another person, who attended one of my Workshops on Pumps. It was well-ingrained on his mind that flooding has to be good enough to provide adequate NPSHa, greater than NPSHr. He was inspecting the testing a pump at the pump-vendor's test bed. And he telephoned me to ask what he should do, can he reject the pump, because the NPSHr was quite large and adequate NPSHa was not available in their system design. I asked him whether the pump-vendor had quoted a 'sellable' value or a real value. He said that the vendor had given only the true value. He admitted that they had not taken care of adequate NPSHa in their system-design. I told him, "You can't reject the pump."

He said, "Sir, But there is no scope to modify the system at this late stage." He also added, that he had pointed this to his Senior. And his senior in that instance also had brushed off the situation saying, "don't worry, nothing will happen. It is flooded suction". This is same what your senior also seems to be saying. It is not uncommon that the people have this wrong notion that a system with flooded suction will not cavitate. Attached photo should be an eye-opener. This damage was happening over a period of some 3 months running of the pump.

Regards,
SLA

On 18 January 2012 05:49, farid farid <bachik_syes@...> wrote:

dear SLA,

1. the value for 0.3 meter is the value that NPSHa of the pump that my senior engineer designed for a crude oil plant.. nothing relate to NPSHr formula that i post to you. it is just my enother question. then i ask him (my senior engineer) back, the pump might cavitate since the value is very low.but he said no worries because pump vendor said no problem as long as the pipe full of liquid. then i kind of 'confuse' with him. because for me, even full of liquid or not, as the pressure inside the pipe approaching the vapor pressure of the liquid, they will start to vaporise right? then he said "vaporise??" how the fluid can vaporise inside a full of fluid in pipe? since he is my senior, then i said ill check back and confirm with you.

2. for the formula from JGC, ill check back the formula and go through your explainantion. ill get back to you later. but appriciate if you can confirm with me whether that formula can be used/valid or not..

thank you so much SLA for your reply and detail explainantion

rgds
MFK

From: S. L. Abhyankar <sl.abhyankar@...>
To: farid farid <bachik_syes@...>
Cc: Jacques Chaurette <jacqueschaurette@...>; pumpfundamentals@yahoogroups.com
Sent: Tuesday, January 17, 2012 4:36 PM

Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

Dear Mr. Farid,As clarified by Mr. Jacques, number of poles and frequency determine the speed of the motor. The formula is Speed of motor = 120 * f / p,where f = frequency in Hz andp = number of poles. For example, 50 Hz supply and 2-pole motor, speed = 3000 rpm. This speed is the synchronous speed. Induction motors will have a slip. This will be dictated by the design of the motor, most prominently by the air-gap between stator and rotor. If slip is 2 %, actual speed will be 0.98 * 3000 = 2940 rpm. That is why you find all those odd values in the tabulation. I am also curious to know the source of your equation for NPSHr !Default value of Sn (Suction specific speed) as 11000 and flow in m3/hr seems to be an odd combination. Value such as 11000 will mostly be in US units and flow in m3/hr is in metric units. I am getting skeptical about the equation ! Regards,SLA
On 16 January 2012 17:43, Jacques Chaurette <jacqueschaurette@...> wrote:

Hello Farid, the no. of poles determines the speed of the motor, the speed of the motor is also determined by the frequency, 60 hz in North America, 50 hz in many other places, Europe for example.

Where does the equation for NPSHR come from?

Jacques Chaurette

http://www.pumpfundamentals.com

Learn about pumps

http://www.chordsandguitar.com

Easy access, FREE, beautiful guitar chords

From: farid farid [mailto:bachik_syes@...]
Sent: Sunday, January 15, 2012 9:40 PM
To: jacqueschaurette@...; pumpfundamentals@yahoogroups.com
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

first of all, i would like to thanks to both SLA and JC for you response abount pump. next i do have the other question and sorry if my question is kind of simple/silly question since i am a newbie im pump technology.

my questions are

1. I dont know what is actually "frequency" and "pole" that relate to the pump. i get this from JGC (japan standard). refer attach file for further detail about frequency and pole. this is used when we want to specify the rotational speed of the pump.

2. i make a calculation for NPSHa and suppose i need to compare with NPSHr. but letsay i dont have the NPSHr value (since the pump is very old 1975) and the pump curve is not available, then how do i estimate/ calculate the NPSHr? can i use equation

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

frm: "jacqueschaurette@..." <jacqueschaurette@...>
To: pumpfundamentals@yahoogroups.com
Cc: bachik_syes@...; pumpfundamentals@yahoogroups.com
Sent: Saturday, January 7, 2012 3:07 AM
Subject: Re : Re: [pumpfundamentals] Re: minimmum flow line

Dear SLA, thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques ----- Message d'origine -----De: "S. L. Abhyankar" <sl.abhyankar@...>Date: Vendredi, 6 Janvier 2012, 1:01 pmObjet: Re: [pumpfundamentals] Re: minimmum flow lineÀ: Jacques Chaurette <jacqueschaurette@...>Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365 चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#208

From: freddy marpaung <freddy_marpaung@...>
Date: Thu Jan 19, 2012 10:07 am
Subject: How to install the inverter on the pump

freddy_marpaung

Send Email

Dear,

Mr. Jacques

I want to ask what data must be completed before installing variable speed drives on chiller pump, because I was afraid would happen abnormal conditions on the chiller when installing VSDs on the pumps. As additional information that the data are available only electrical measurement data. Because the flow meter and pump characteristic curve is not available. another question is how to choose the right inverter.
This is the technical specification of chiller and pump:

No	Parameter	Chiller 1,3,4	Chiller 5,6
No	Parameter	30GBN400	30GTN420
1	Refrigeran	R22	R22
2	Chill water pump	90 KW	30 KW
3	Chiller capacity	400 Ton Ref	420 Ton Ref
4	Power input compressor	45 kW	45 kW
5	Chill water temperature	-	-
6	In let	13 ^oC	13 ^oC
7	Out let (setting)	5 ^oC	6 ^oC

I will gladly wait for a reply from you. and for your help I thank you

Warmest regards

Freddy Marpaung

Reply | Messages in this Topic (10)

#209

From: "Jacques" <jchaurette@...>
Date: Thu Jan 19, 2012 1:57 pm
Subject: Re: How to install the inverter on the pump

jchaurette

Send Email

Hello Freddy, if you put the question adressed only to me people will think that
I am the only one to answer. Please address your question to everyone, this way
you will benifit from many points of view.

Jacques

--- In pumpfundamentals@yahoogroups.com, freddy marpaung <freddy_marpaung@...>
wrote:
>
> Dear,
> Mr. Jacques
>
> I want to ask what data must be completed before installing variable speed
drives on chiller pump, because I was afraid would happen abnormal conditions on
the chiller when installing VSDs on the pumps.As additional information that the
data are available only electrical measurement data. Because the flow meter and
pump characteristic curve is not available. another question is how to choose
the right inverter.
> This is the technical specification of chiller and pump:
>
>
> No Parameter Chiller 1,3,4 Chiller 5,6
> 30GBN400 30GTN420
> 1 Refrigeran R22 R22
> 2 Chill water pump
>  90 KW 30 KW
> 3 Chiller capacity
>  400 Ton Ref 420 Ton Ref
> 4 Power input compressor 45 kW 45 kW
> 5 Chill water temperature
>  - -
> 6 In let �13 oC � 13 oC
> 7 Out let (setting) 5 oC 6� oC
> I will gladly wait for a reply from you. and for your help I thank you
>
> Warmest regards
>
> Freddy Marpaung
>

Reply | Messages in this Topic (10)

#210

From: "tomswift2x" <tomswift2x@...>
Date: Fri Jan 20, 2012 1:01 am
Subject: Confused how to use the pipe friction app with pump data.

tomswift2x

Send Email

I'm feeling lost. But found your web site, and your apps, and I've been studying
them. I hope I'm not overly imposing on any forum rules or members.

I look at a Grundfoss hot water pump (specs included below). Then I look at the
pipe friction loss applet. I'm going to pump hot water from a 4' high tank at
ground level through a  50' horizontal run through a copper pipe, then split the
pipe, sending 1 gpm 22' up to a heat exchanger and back down to ground level,
and the other fork sending 5 gpm 6' up to a heat exchanger and back down, the
two return lines joining and returning the 50' along the ground to the original
heated tank. I'll use an adjustable valve just before the lower heat exchanger
to force the flow  upward to assure that the 1gpm does flow through the upper
heat exchanger. So, once I get the lines primed and the water is circulating,
how does the pipe friction loss applet help me predict the best pipe size? Do I
tell the app I want to move 6gpm total? or do I use the figures from the pump
data, say, 33gpm, since the water isn't really being lifted (once the
circulation is established)?

Thanks,
Tom

Here's the pump data from the catalog. 
http://www.grainger.com/Grainger/GRUNDFOS-Circulator-Pump-4JA10

Item  Circulator Pump
Type  Closed Loop
HP  1/6
Voltage  115
Phase  1
Amps  2.15
Inlet/Outlet  Flanged
Housing Material  Cast Iron
Face to Face Dimension (In.)  6-1/2
Max. Temp. (F)  230
Max. Working Pressure (PSI)  145
Flange/Union Included  No
Shut-Off (Ft.)  32
RPM  3000
Impeller Material  PES Composite
Shaft Material  Aluminum Oxide Ceramic
Thermal Protection  Auto
GPM of Water @ 1 Ft. of Head  33
GPM of Water @ 2 Ft. of Head  32
GPM of Water @ 3 Ft. of Head  31
GPM of Water @ 4 Ft. of Head  30
GPM of Water @ 5 Ft. of Head  29.2
GPM of Water @ 6 Ft. of Head  5
GPM of Water @ 7 Ft. of Head  28
GPM of Water @ 10 Ft. of Head  25.4
GPM of Water @ 13 Ft. of Head  23
GPM of Water @ 15 Ft. of Head  21.5
GPM of Water @ 20 Ft. of Head  17
GPM of Water @ 25 Ft. of Head  12
GPM of Water @ 30 Ft. of Head  5
Length (In.)  6-1/2
Width (In.)  4-1/8
Max. GPM @ Head (Ft.)  33 @ 1
Best Efficiency GPM @ Head (Ft.)  12 @ 18
Min. GPM @ Head (Ft.)  12 @ 25
Drive Type  Direct
Bearing Type  Carbon/Thrust
Mechanical Seal  Wet Rotor
Manufacturers Warranty Length  2 Years
Includes  Flange Bolts And Gaskets

Reply | Messages in this Topic (11)

#211

From: Jacques Chaurette <jacqueschaurette@...>
Date: Fri Jan 20, 2012 1:21 am
Subject: RE: Confused how to use the pipe friction app with pump data.

jacqueschaurette@...

Send Email

Hi Tom, can you provide a flow schematic please.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of tomswift2x
Sent: Thursday, January 19, 2012 8:02 PM
To: pumpfundamentals@yahoogroups.com
Subject: [pumpfundamentals] Confused how to use the pipe friction app with pump data.

I'm feeling lost. But found your web site, and your apps, and I've been studying them. I hope I'm not overly imposing on any forum rules or members.

I look at a Grundfoss hot water pump (specs included below). Then I look at the pipe friction loss applet. I'm going to pump hot water from a 4' high tank at ground level through a 50' horizontal run through a copper pipe, then split the pipe, sending 1 gpm 22' up to a heat exchanger and back down to ground level, and the other fork sending 5 gpm 6' up to a heat exchanger and back down, the two return lines joining and returning the 50' along the ground to the original heated tank. I'll use an adjustable valve just before the lower heat exchanger to force the flow upward to assure that the 1gpm does flow through the upper heat exchanger. So, once I get the lines primed and the water is circulating, how does the pipe friction loss applet help me predict the best pipe size? Do I tell the app I want to move 6gpm total? or do I use the figures from the pump data, say, 33gpm, since the water isn't really being lifted (once the circulation is established)?

Thanks,
Tom

Here's the pump data from the catalog. http://www.grainger.com/Grainger/GRUNDFOS-Circulator-Pump-4JA10

Item Circulator Pump
Type Closed Loop
HP 1/6
Voltage 115
Phase 1
Amps 2.15
Inlet/Outlet Flanged
Housing Material Cast Iron
Face to Face Dimension (In.) 6-1/2
Max. Temp. (F) 230
Max. Working Pressure (PSI) 145
Flange/Union Included No
Shut-Off (Ft.) 32
RPM 3000
Impeller Material PES Composite
Shaft Material Aluminum Oxide Ceramic
Thermal Protection Auto
GPM of Water @ 1 Ft. of Head 33
GPM of Water @ 2 Ft. of Head 32
GPM of Water @ 3 Ft. of Head 31
GPM of Water @ 4 Ft. of Head 30
GPM of Water @ 5 Ft. of Head 29.2
GPM of Water @ 6 Ft. of Head 5
GPM of Water @ 7 Ft. of Head 28
GPM of Water @ 10 Ft. of Head 25.4
GPM of Water @ 13 Ft. of Head 23
GPM of Water @ 15 Ft. of Head 21.5
GPM of Water @ 20 Ft. of Head 17
GPM of Water @ 25 Ft. of Head 12
GPM of Water @ 30 Ft. of Head 5
Length (In.) 6-1/2
Width (In.) 4-1/8
Max. GPM @ Head (Ft.) 33 @ 1
Best Efficiency GPM @ Head (Ft.) 12 @ 18
Min. GPM @ Head (Ft.) 12 @ 25
Drive Type Direct
Bearing Type Carbon/Thrust
Mechanical Seal Wet Rotor
Manufacturers Warranty Length 2 Years
Includes Flange Bolts And Gaskets

Reply | Messages in this Topic (11)

#212

From: freddy marpaung <freddy_marpaung@...>
Date: Fri Jan 20, 2012 1:26 am
Subject: How to install the inverter on the pump

freddy_marpaung

Send Email

Dear,

Everyone

No	Parameter	Chiller 1,3,4	Chiller 5,6
No	Parameter	30GBN400	30GTN420
1	Refrigeran	R22	R22
2	Chill water pump	90 KW	30 KW
3	Chiller capacity	400 Ton Ref	420 Ton Ref
4	Power input compressor	45 kW	45 kW
5	Chill water temperature	-	-
6	In let	13 ^oC	13 ^oC
7	Out let (setting)	5 ^oC	6 ^oC

I will gladly wait for a reply from you. and for your help I thank you

Warmest regards

Freddy Marpaung

Reply | Messages in this Topic (10)

#213

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Fri Jan 20, 2012 4:42 am
Subject: Re: Re : Re: Re: minimmum flow line

sl_abh

Send Email

Dear Farid,

People use different formulas for specific speed -

It seems JGC's formula has the logic of having Q in m3/min., maybe because rpm is also per minute. But because Q is under radical sign, it does not help.

The formula from "Impeller Pumps" by Troskolansky & Lazarkiewitz is -
Ns = n*sqrt(Q in m3/s) / (H^0.75)

With Q in m3/s at least the value is in basic metric units of length and time. One could have Hz instead of rpm. But the value becomes very small. So taking rpm becomes just like having a constant 60 as multiplier in the formula. Or we can say

Ns = 60*Hz*sqrt(Q in m3/s) / (H^0.75)

Actually the original idea was to make the formula for Specific Speed, such that it will become a non-dimensional quantity, like specific gravity. In "Impeller Pumps" by Troskolansky & Lazarkiewitz, there is mention also of Nf. But what is in common usage is Ns.

If one has Q in m3/h, to use the formula Ns = 60*Hz*sqrt(Q in m3/s) / (H^0.75), we have to have

Ns = 60*Hz*sqrt((Q in m3/h)/3600) / (H^0.75)

This becomes Ns = 60*Hz*sqrt(Q in m3/h) / 60 / (H^0.75)

That is why I said earlier '60' should be outside the parenthesis and in the denominator.

But I have seen metrication of HI standards giving Ns metric as Ns = RPM * sqrt(Q in m3/h) / (H^0.75). So that is another, "American Metric Specific Speed" !!

If we want to use the formula for NPSHr from JGC, we have to have Ns also as per their formula (of JGC), because their formula for NPSHr must have been derived considering their formula for Ns.

About dividing H by 2, the logic is similar to why you divide Q for a double suction pump. For Ns, one is primarily interested in the basic design of the impeller. For a double suction pump we are interested in Q going to one side of the impeller. Likewise in a two-stage or multistage pump, we should be interested in H developed by one impeller. Since the pump in this case is a two-stage pump it should be H/2.

In my Workshops I give most general formula for Ns = (n in RPM) * sqrt (Q per suction in m3/s) / (H per stage)^0.75

I hope, this clarifies the specific speed issue.

On class-rating of valves and piping, you are right that most commonly #300 rating is not needed on suction side. But in your sketch, I also notice 16" valve both on suction and discharge. So #300 might have been selected for suction side also, with the idea to reduce variety in inventory.

But a 16" line has been reduced to 8" on the suction side ! This sounds odd. But, maybe it is so provided, because the pump's suction is 8".

Regards,
SLA

On 19 January 2012 14:52, farid farid <bachik_syes@...> wrote:

Dear SLA

Firstly I would like to thanks so much for your very supportive answer. I hope god will bless you

1. Yes, my silly mistakes, NPSHa should be for systems and NPSHr is for the pump.

2. Regarding you response about the calculation of specific speed, just now u claimed that,

                a. 60 should be outside of square root 2

                b. differential head (H) should be divided by 2.

                c. And unit of Q should be in m3/s not m3/h

But as per standard (JGC), the equation 8 is as per attachment 1. So I don’t know which one is true either you or the standard. Hope you can confirm with me later. You can refer attachment 2 for further example for NPSHr and specific speed calculation.

3. appreciate if you can confirm with me whether the formula of NPSHr estimation can be used or not.

I do have one question to you

As I observed one of the P&ID from my client, the pipe suction rating is 150# half and 300# half and the discharge is 300#. Can refer picture for further detail. My question is: what is the concern that to install 300# rating pipe at pump suction. Why they don’t use 150# since the pressure at the pump suction are low. At discharge side, it must be 300# rating since the discharge pressure is about 33bar. But let say they do have recirculation line that go back to the suction pipe, then is reliable to have 300# at the suction side. As for now, I don’t see any recirculation line at the pump suction and it seems useless to have 300# pipe rating at pump suction. Refer pic for the sketch. pls ignore the pipe size. hopefully you can anwer my question. thank you for spending your time answering to my email.

regards

MFK

From: S. L. Abhyankar <sl.abhyankar@...>
To: farid farid <bachik_syes@...>
Cc: pumpfundamentals@yahoogroups.com; Jacques Chaurette <jacqueschaurette@...>
Sent: Thursday, January 19, 2012 1:40 AM

Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

Dear Farid,

I read both - your message below and also latest reply from Mr. Jacques.

But I would first respond to your message below.

You have mentioned right in the first line "...NPSHa of the pump..". NPSHa is of the system, not of the pump. NPSHr is of the pump. And it is a rule that NPSHa > NPSHr.

Your senior saying that the pump vendor would take care of it is not wrong, only if the pump is designed and constructed that way. I myself designed a pump for LPG bottling plant, even when the purchase specification said, "NPSHa = 0" ! But it was a special design, special that NPSHr + margin was in-built in pump design by putting the pump assembly in a can so that the suction impeller gets adequate NPSHa. It was no magic that I did. It is common for pumps in critical applications as LPG or condensate extraction are built this way. The vendor has to be knowledgeable and competent.

Your senior is not right in thinking that a pump with flooded suction will not suffer cavitation-damage. I attach herewith a photo of an impeller where every blade of the impeller has metal dug out and at an almost average diameter on all blades. I got this photo when I was invited by my friend Mr. Sudhir Kale in Jakarta. He is Vice President Operations in a steel mill, Pt. Jakarta Cakratunggal Steel Mills.

The impeller was from a pump in their cooling water system, where the suction sump has water about 1.5 m above pump's suction. Yet the impeller was suffering severe cavitation damage.

There was another person, who attended one of my Workshops on Pumps. It was well-ingrained on his mind that flooding has to be good enough to provide adequate NPSHa, greater than NPSHr. He was inspecting the testing a pump at the pump-vendor's test bed. And he telephoned me to ask what he should do, can he reject the pump, because the NPSHr was quite large and adequate NPSHa was not available in their system design. I asked him whether the pump-vendor had quoted a 'sellable' value or a real value. He said that the vendor had given only the true value. He admitted that they had not taken care of adequate NPSHa in their system-design. I told him, "You can't reject the pump."

He said, "Sir, But there is no scope to modify the system at this late stage." He also added, that he had pointed this to his Senior. And his senior in that instance also had brushed off the situation saying, "don't worry, nothing will happen. It is flooded suction". This is same what your senior also seems to be saying. It is not uncommon that the people have this wrong notion that a system with flooded suction will not cavitate. Attached photo should be an eye-opener. This damage was happening over a period of some 3 months running of the pump.

Regards,
SLA

On 18 January 2012 05:49, farid farid <bachik_syes@...> wrote:

dear SLA,

1. the value for 0.3 meter is the value that NPSHa of the pump that my senior engineer designed for a crude oil plant.. nothing relate to NPSHr formula that i post to you. it is just my enother question. then i ask him (my senior engineer) back, the pump might cavitate since the value is very low.but he said no worries because pump vendor said no problem as long as the pipe full of liquid. then i kind of 'confuse' with him. because for me, even full of liquid or not, as the pressure inside the pipe approaching the vapor pressure of the liquid, they will start to vaporise right? then he said "vaporise??" how the fluid can vaporise inside a full of fluid in pipe? since he is my senior, then i said ill check back and confirm with you.

2. for the formula from JGC, ill check back the formula and go through your explainantion. ill get back to you later. but appriciate if you can confirm with me whether that formula can be used/valid or not..

thank you so much SLA for your reply and detail explainantion

rgds

MFK

From: S. L. Abhyankar <sl.abhyankar@...>
To: farid farid <bachik_syes@...>
Cc: Jacques Chaurette <jacqueschaurette@...>; pumpfundamentals@yahoogroups.com
Sent: Tuesday, January 17, 2012 4:36 PM
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

Dear Mr. Farid,As clarified by Mr. Jacques, number of poles and frequency determine the speed of the motor. The formula is Speed of motor = 120 * f / p,where f = frequency in Hz andp = number of poles. For example, 50 Hz supply and 2-pole motor, speed = 3000 rpm. This speed is the synchronous speed. Induction motors will have a slip. This will be dictated by the design of the motor, most prominently by the air-gap between stator and rotor. If slip is 2 %, actual speed will be 0.98 * 3000 = 2940 rpm. That is why you find all those odd values in the tabulation. I am also curious to know the source of your equation for NPSHr !Default value of Sn (Suction specific speed) as 11000 and flow in m3/hr seems to be an odd combination. Value such as 11000 will mostly be in US units and flow in m3/hr is in metric units. I am getting skeptical about the equation ! Regards,SLA

On 16 January 2012 17:43, Jacques Chaurette <jacqueschaurette@...> wrote:

Hello Farid, the no. of poles determines the speed of the motor, the speed of the motor is also determined by the frequency, 60 hz in North America, 50 hz in many other places, Europe for example.

Where does the equation for NPSHR come from?

Jacques Chaurette

http://www.pumpfundamentals.com

Learn about pumps

http://www.chordsandguitar.com

Easy access, FREE, beautiful guitar chords

From: farid farid [mailto:bachik_syes@...]
Sent: Sunday, January 15, 2012 9:40 PM
To: jacqueschaurette@...; pumpfundamentals@yahoogroups.com
Subject: Re: Re : Re: [pumpfundamentals] Re: minimmum flow line

first of all, i would like to thanks to both SLA and JC for you response abount pump. next i do have the other question and sorry if my question is kind of simple/silly question since i am a newbie im pump technology.

my questions are

1. I dont know what is actually "frequency" and "pole" that relate to the pump. i get this from JGC (japan standard). refer attach file for further detail about frequency and pole. this is used when we want to specify the rotational speed of the pump.

2. i make a calculation for NPSHa and suppose i need to compare with NPSHr. but letsay i dont have the NPSHr value (since the pump is very old 1975) and the pump curve is not available, then how do i estimate/ calculate the NPSHr? can i use equation

NPSHr= (0.82) ((N (Qd)^0.5)/Sn)^(4/3)+0.6

where:

N=speed of rotation (RPM)

Sn=suction specific speed (default=11000)

Qd= rated flowrate (m3/h

i think thats all..appriciate if can answer my question.

rgds

MFK

frm: "jacqueschaurette@..." <jacqueschaurette@...>
To: pumpfundamentals@yahoogroups.com
Cc: bachik_syes@...; pumpfundamentals@yahoogroups.com
Sent: Saturday, January 7, 2012 3:07 AM
Subject: Re : Re: [pumpfundamentals] Re: minimmum flow line

Dear SLA, thanks once again for your valuable input. Unfortunately I disagree, the line must remain under pressure to garantee instant coverage of water from the sprinkler(s) head(s) in case of fire. I don`t know why the jockey pumps are breaking, it should be set to start at a given low pressure and stop at a set high pressure with a reasonable dead zone. The pump will probably run for no more than a few minutes and stop on high pressure. If it stops and starts too often there is a serious leakage in the system that must be fixed.

cheers,

Happy new year

Jacques ----- Message d'origine -----De: "S. L. Abhyankar" <sl.abhyankar@...>Date: Vendredi, 6 Janvier 2012, 1:01 pmObjet: Re: [pumpfundamentals] Re: minimmum flow lineÀ: Jacques Chaurette <jacqueschaurette@...>Cc: bachik_syes@..., pumpfundamentals@yahoogroups.com

Dear Mr. Jacques Chaurette,

Both of us have passion to look into problems on pumping, right ? It is that passion, which has motivated you to start this group ! I appreciate that very much.

On another group, there was a post of repetitive failure (breakage !) of the shaft of a jockey pump. I guess, just to maintain the line pressure to take care of leakage, the jockey pump would keep running, even if the flow being pumped is too small, the leakage being small. Jockey pump had a pressure-switch control set at 15.4 bar whereas main pump rating was 12 bar. These pressure-settings seem to be unduly high. Pressure-switch setting of 12.5 bar for the jockey pump should be good enough and at that pressure the jockey pump would be safely away from safe minimum flow. Then shaft-failures would not happen.

Alternatively, instead of pressure setting one could explore using level control, to ensure that the line is full at the topmost point. If the level goes down by 5 m or so, that event should activate the jockey pump. Pump should get cut off when topmost level is reached. That is what I meant by "line should remain charged does not mean it should be under pressure."

Regards,
SLA

On 6 January 2012 16:52, Jacques Chaurette <jacqueschaurette@...> wrote:

Thank you SLA for these great answers and especially for taking the time. I would however offer the following corrections in red.

Jacques

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of S. L. Abhyankar
Sent: Friday, January 06, 2012 1:23 AM
To: bachik_syes@...
Cc: pumpfundamentals@yahoogroups.com
Subject: Re: [pumpfundamentals] Re: minimmum flow line

Can i know what is shut off pressure?

"Shut off pressure" refers to the pressure, when the discharge valve is 'shut off'. Usually this is the maximum pressure the pump will develop. Standards for fire-fighting pump do not desire shut-off pressure (head) to be higher than 1.2 times of rated head. See NFPA 20 for more details

can pump running when discharge valve closed for a long period of time i.e 1 day?

Pump running with discharge valve closed even for 5 minutes will be risky !

Normally lines of fire-fighting systems are expected to stay fully charged. But 'staying charged' does not mean that the line should be under pressure. It should be full. That is it. In this type of system the line must remain under pressure, because on big systems there are always small leaks, a jockey pump (small pump) is used to keep the system pressurized.

Usually the non-return valve on the discharge pipe will ensure that water pumped by the pump when it is running will stay in the pipeline even after the pump is shut down. That helps the line to stay charged.

how we decide the right pump for that system?

Two main parameters for selecting a pump are required flow-rate and total head. Both are to be decided by the user according to the system.

Total head has two parts (1) static head (2) friction head

If pump has to discharge into a pressurized vessel, e.g. boiler drum, the pressure is to be converted into equivalent static head and to be added to the part (1) static head

One needs to add velocity head if discharge pipe size is smaller than suction pipe size. But one can add 1 m for that, which is more than enough.

Static head is usually clear from the plant layout.

Friction head needs to be calculated from reference charts, tables, etc. For these types of systems, the Hazen-Williams friction formula must be used because the NFPA stipulates that it be used.

One needs to consider "equivalent lengths" of various fittings and valves

Regards,
SLA

On 6 January 2012 06:20, farid farid <bachik_syes@...> wrote:

i do have 3 questions

1. can i know what is shut off pressure?

from my understanding, shut off pressure is the the higest pressure that can be produced by a pump and this happened at zero flow i.e. control valve closed at discharge line. so when pump running during discharge valve closed, the pressure builed up in the pipe line until a maximum pressure and this maximum pressure is shut off pressure. am i right?

2. can pump running when discharge valve closed for a long period of time i.e 1 day? or is this will make the pump damage? from my knowledge, in the pipeline usually they have pressure transmitter which can detect high pressure in pipeline and will trip the pump once the pressure exceed the level. hope can correct me if i am wrong.

3. in order to size a pump, we need to know the total head of the system which is discharge head - suction head. then we get the total head. then how we decide the right pump for that system?

appriciate if can answer my questions as i am very interested in pump=)

thank you

-- Cordially, S. L. Abhyankar

सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.com http://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365 चलितभाष-क्रमाङ्कः +91 9757 21 5527
-- Cordially, S. L. Abhyankarसस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"http://slabhyankar.wordpress.comhttp://study1geetaa2sanskrit.wordpress.com/http://slez-musings.blogspot.comस्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (18)

#214

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Fri Jan 20, 2012 5:14 am
Subject: Re: How to install the inverter on the pump

sl_abh

Send Email

On 20 January 2012 10:36, S. L. Abhyankar <sl.abhyankar@...> wrote:

Dear Mr. Freddy,

Is it possible that 30 kw mentioned for Chillers 5,6 is 'per pump' and 90 kW mentioned for Chillers 1, 3, 4 is for 3 pumps together ? That will make all pump and chillers identical.

The difference in refrigeration capacities 400 and 420 seems marginal.

In fact there is no logic for pump(s) in 400 T refrigeration capacity to be 90 kW whereas the pump(s) in 420 T (higher) refrigeration capacity are 30 kW (1/3 of 90 kW).

The VSD is never common. It is always dedicated to each motor. Selection of VSD is primarily dictated by motor-rating and the range of speed-variation required in an application.

Also, VSD is useful for energy-saving and to avoid too many pumps in an installation. A combination of having number of pumps and having also VSD may not help much. It may rather complicate O&M by the increase in number of engineering devices in the system.

Regards,
SLA

On 19 January 2012 15:37, freddy marpaung <freddy_marpaung@...> wrote:

Dear,
Mr. Jacques

I want to ask what data must be completed before installing variable speed drives on chiller pump, because I was afraid would happen abnormal conditions on the chiller when installing VSDs on the pumps. As additional information that the data are available only electrical measurement data. Because the flow meter and pump characteristic curve is not available. another question is how to choose the right inverter.
This is the technical specification of chiller and pump:

No

Parameter

Chiller 1,3,4

Chiller 5,6

30GBN400

30GTN420

1

Refrigeran

R22

R22

2

Chill water pump

90 KW

30 KW

3

Chiller capacity

400 Ton Ref

420 Ton Ref

4

Power input compressor

45 kW

45 kW

5

Chill water temperature

-

-

6

In let

13 ^oC

13 ^oC

7

Out let (setting)

5 ^oC

6 ^oC

I will gladly wait for a reply from you. and for your help I thank you

Warmest regards

Freddy Marpaung

--
Cordially, S. L. Abhyankar
सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् ।"
http://slabhyankar.wordpress.com
http://study1geetaa2sanskrit.wordpress.com/
http://slez-musings.blogspot.com
स्थापित-दूरभाष-क्रमाङ्कः +91 22 2849 5365
चलितभाष-क्रमाङ्कः +91 9757 21 5527

Reply | Messages in this Topic (10)

#215

From: freddy marpaung <freddy_marpaung@...>
Date: Fri Jan 20, 2012 8:21 am
Subject: How to install the inverter on the pump

freddy_marpaung

Send Email

Dear Mr. SLA

Firstly I would like to thanks so much for your very supportive answer. I hope God will bless you

the reason I installed VSD on chiller pumps is due to the percentage loading capacity of 90 kW pump is maximum 60%. with this condition discharge valve closed 50% this is because the pressure chilled water in Air Handling Unit (AHU) is very high.
Here I attach a detailed layout diagram of chilled water systems.

With a record for the booster pump outlet after the header on the image attachment does not use anymore.

hopefully you can anwer my question. thank you for spending your time answering to my email.

Regards,

Freddy M

Reply | Messages in this Topic (10)

#216

From: "S. L. Abhyankar" <sl.abhyankar@...>
Date: Sat Jan 21, 2012 12:03 am
Subject: Re: How to install the inverter on the pump

sl_abh

Send Email

Dear Freddy,

Your query was about method of selecting VSD. My answer was that selection of VSD is primarily influenced by the motor rating. If you have already installed VSD with due diligence, your query is answered by yourself.

Now when you say that percentage loading capacity of 90 kW pump is maximum 60%, I wonder whether the system was over-designed and in turn the pump also became selected with excessive capacity.

Since the pumps cannot be replaced as easily, your logic of installing the VSD seems logical.

Regards,
SLA

On 20 January 2012 13:51, freddy marpaung <freddy_marpaung@...> wrote:

Dear Mr. SLA

Firstly I would like to thanks so much for your very supportive answer. I hope God will bless you

the reason I installed VSD on chiller pumps is due to the percentage loading capacity of 90 kW pump is maximum 60%. with this condition discharge valve closed�50% this is because the pressure�chilled water in Air Handling Unit (AHU) is very high.
Here I attach a detailed layout diagram of chilled water systems.

With a record for the booster pump outlet after the header on the image attachment does not use anymore.

hopefully you can anwer my question. thank you for spending your time�answering to my email.

Regards,

Freddy M

Reply | Messages in this Topic (10)

#217

From: "tomswift2x" <tomswift2x@...>
Date: Mon Jan 23, 2012 9:37 pm
Subject: Re: Confused how to use the pipe friction app with pump data.

tomswift2x

Send Email

Thank you. I'll paste a png graphic below. I hope this explains what I tried to describe earlier. That's a pump at the bottom of the water tank. The tank contains heated water. It provides heat to the two heat exchangers. The upper h.ex. uses 1gpm, the lover uses 5 gpm. I've included an adjustable valve before the lower heat exchanger to force and adjust the volume of hot water that travels up to the heat exchanger.

--- In pumpfundamentals@yahoogroups.com, Jacques Chaurette <jacqueschaurette@...> wrote:
>
> Hi Tom, can you provide a flow schematic please.
>
>
>
> Jacques
>
> _____
>
> From: pumpfundamentals@yahoogroups.com
> [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of tomswift2x
> Sent: Thursday, January 19, 2012 8:02 PM
> To: pumpfundamentals@yahoogroups.com
> Subject: [pumpfundamentals] Confused how to use the pipe friction app with
> pump data.
>
>
>
>
>
> I'm feeling lost. But found your web site, and your apps, and I've been
> studying them. I hope I'm not overly imposing on any forum rules or members.
>
> I look at a Grundfoss hot water pump (specs included below). Then I look at
> the pipe friction loss applet. I'm going to pump hot water from a 4' high
> tank at ground level through a 50' horizontal run through a copper pipe,
> then split the pipe, sending 1 gpm 22' up to a heat exchanger and back down
> to ground level, and the other fork sending 5 gpm 6' up to a heat exchanger
> and back down, the two return lines joining and returning the 50' along the
> ground to the original heated tank. I'll use an adjustable valve just before
> the lower heat exchanger to force the flow upward to assure that the 1gpm
> does flow through the upper heat exchanger. So, once I get the lines primed
> and the water is circulating, how does the pipe friction loss applet help me
> predict the best pipe size? Do I tell the app I want to move 6gpm total? or
> do I use the figures from the pump data, say, 33gpm, since the water isn't
> really being lifted (once the circulation is established)?
>
> Thanks,
> Tom
>
> Here's the pump data from the catalog.
> http://www.grainger.com/Grainger/GRUNDFOS-Circulator-Pump-4JA10
>
> Item Circulator Pump
> Type Closed Loop
> HP 1/6
> Voltage 115
> Phase 1
> Amps 2.15
> Inlet/Outlet Flanged
> Housing Material Cast Iron
> Face to Face Dimension (In.) 6-1/2
> Max. Temp. (F) 230
> Max. Working Pressure (PSI) 145
> Flange/Union Included No
> Shut-Off (Ft.) 32
> RPM 3000
> Impeller Material PES Composite
> Shaft Material Aluminum Oxide Ceramic
> Thermal Protection Auto
> GPM of Water @ 1 Ft. of Head 33
> GPM of Water @ 2 Ft. of Head 32
> GPM of Water @ 3 Ft. of Head 31
> GPM of Water @ 4 Ft. of Head 30
> GPM of Water @ 5 Ft. of Head 29.2
> GPM of Water @ 6 Ft. of Head 5
> GPM of Water @ 7 Ft. of Head 28
> GPM of Water @ 10 Ft. of Head 25.4
> GPM of Water @ 13 Ft. of Head 23
> GPM of Water @ 15 Ft. of Head 21.5
> GPM of Water @ 20 Ft. of Head 17
> GPM of Water @ 25 Ft. of Head 12
> GPM of Water @ 30 Ft. of Head 5
> Length (In.) 6-1/2
> Width (In.) 4-1/8
> Max. GPM @ Head (Ft.) 33 @ 1
> Best Efficiency GPM @ Head (Ft.) 12 @ 18
> Min. GPM @ Head (Ft.) 12 @ 25
> Drive Type Direct
> Bearing Type Carbon/Thrust
> Mechanical Seal Wet Rotor
> Manufacturers Warranty Length 2 Years
> Includes Flange Bolts And Gaskets
>

Reply | Messages in this Topic (11)

#218

From: freddy marpaung <freddy_marpaung@...>
Date: Tue Jan 24, 2012 1:53 am
Subject: RE: How to install the inverter on the pump

freddy_marpaung

Send Email

Dear Mr. SLA

my intention to install a VSD on the pump is to reduce energy consumption at the pump, the current state of the pump rotation speed constant while the chiller cooling load vary. I want to ask for input consideration what should I look for when installing the VSD so that the VSD to work as expected.

Regards,

Freddy

----- Forwarded Message -----
From: S. L. Abhyankar <sl.abhyankar@...>
To: freddy marpaung <freddy_marpaung@...>
Cc: "pumpfundamentals@yahoogroups.com" <pumpfundamentals@yahoogroups.com>
Sent: Saturday, January 21, 2012 7:03 AM
Subject: Re: How to install the inverter on the pump

On 20 January 2012 13:51, freddy marpaung <freddy_marpaung@...> wrote:

Dear Mr. SLA

Firstly I would like to thanks so much for your very supportive answer. I hope God will bless you

the reason I installed VSD on chiller pumps is due to the percentage loading capacity of 90 kW pump is maximum 60%. with this condition discharge valve closed 50% this is because the pressure chilled water in Air Handling Unit (AHU) is very high.
Here I attach a detailed layout diagram of chilled water systems.

With a record for the booster pump outlet after the header on the image attachment does not use anymore.

hopefully you can anwer my question. thank you for spending your time answering to my email.

Regards,

Freddy M

Reply | Messages in this Topic (10)

#219

From: "Juned Ansari" <juned.ansari@...>
Date: Tue Jan 24, 2012 7:56 am
Subject: RE: RE: How to install the inverter on the pump

firdousdream001

Send Email

Most importantly the motor should be compatible to be fitted with a VSD. Speed reduction involves lot of heat generation and a suitable means of dissipation of the same should be present to avoid motor burnt out.

Mr. Abhyankar: I hope, I am right. You can comment on this a little more.

Regards

Juned Ansari

Secure Meters Limited

Assistant Manager

M: +91-96655-86331

NBI Water

Energy Auditor (EA-9789)

M: +91-94221-61420

Aurangabad

From: pumpfundamentals@yahoogroups.com [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of freddy marpaung
Sent: Tuesday, January 24, 2012 7:24 AM
To: sl.abhyankar@...
Cc: pumpfundamentals@yahoogroups.com
Subject: [pumpfundamentals] RE: How to install the inverter on the pump

Dear Mr. SLA

Regards,

Freddy

On 20 January 2012 13:51, freddy marpaung <freddy_marpaung@...> wrote:

Dear Mr. SLA

Reply | Messages in this Topic (10)

#220

From: "Jacques" <jchaurette@...>
Date: Tue Jan 24, 2012 2:04 pm
Subject: Re: Confused how to use the pipe friction app with pump data.

jchaurette

Send Email

Tom, you need to put the sketch in the File section, Yahoo will not accept them
directly in the e-mail.

Let`s assume you haven`t selected the pump yet and you are trying to find out
what the best pipe size is to use , so that friction can be calculated and a
proper pump selected.

I may get a few of the details wrong since I don`t have the sketch. The first
job is to figure out the critical path, that is the path that offers the most
resistance (i.e. combined static head and friction head).

It looks to me like it might be the consumer that is higher up. Using the pipe
friction app, assume a pipe size and the flow that you want in that branch and
calulate the friction head, add that to the static head for that path. Do the
same for the low consumer. The one that has the greatest head will be the
critical path.

You should be able to adjust the flow with a valve to balance them to your
requirement.

The pump is sized for the total flow and the head will be the head for the
critical path.

Cheers,

Jacques

--- In pumpfundamentals@yahoogroups.com, "tomswift2x" <tomswift2x@...> wrote:
>
> Thank you. I'll paste a png graphic below. I hope this explains what I
> tried to describe earlier. That's a pump at the bottom of the water
> tank. The tank contains heated water. It provides heat to the two heat
> exchangers. The upper h.ex. uses 1gpm, the lover uses 5 gpm. I've
> included an adjustable valve before the lower heat exchanger to force
> and adjust the volume of  hot water that travels up to the heat
> exchanger.
>
> --- In pumpfundamentals@yahoogroups.com, Jacques Chaurette
> <jacqueschaurette@> wrote:
> >
> > Hi Tom, can you provide a flow schematic please.
> >
> >
> >
> > Jacques
> >
> >   _____
> >
> > From: pumpfundamentals@yahoogroups.com
> > [mailto:pumpfundamentals@yahoogroups.com] On Behalf Of tomswift2x
> > Sent: Thursday, January 19, 2012 8:02 PM
> > To: pumpfundamentals@yahoogroups.com
> > Subject: [pumpfundamentals] Confused how to use the pipe friction app
> with
> > pump data.
> >
> >
> >
> >
> >
> > I'm feeling lost. But found your web site, and your apps, and I've
> been
> > studying them. I hope I'm not overly imposing on any forum rules or
> members.
> >
> > I look at a Grundfoss hot water pump (specs included below). Then I
> look at
> > the pipe friction loss applet. I'm going to pump hot water from a 4'
> high
> > tank at ground level through a 50' horizontal run through a copper
> pipe,
> > then split the pipe, sending 1 gpm 22' up to a heat exchanger and back
> down
> > to ground level, and the other fork sending 5 gpm 6' up to a heat
> exchanger
> > and back down, the two return lines joining and returning the 50'
> along the
> > ground to the original heated tank. I'll use an adjustable valve just
> before
> > the lower heat exchanger to force the flow upward to assure that the
> 1gpm
> > does flow through the upper heat exchanger. So, once I get the lines
> primed
> > and the water is circulating, how does the pipe friction loss applet
> help me
> > predict the best pipe size? Do I tell the app I want to move 6gpm
> total? or
> > do I use the figures from the pump data, say, 33gpm, since the water
> isn't
> > really being lifted (once the circulation is established)?
> >
> > Thanks,
> > Tom
> >
> > Here's the pump data from the catalog.
> > http://www.grainger.com/Grainger/GRUNDFOS-Circulator-Pump-4JA10
> >
> > Item Circulator Pump
> > Type Closed Loop
> > HP 1/6
> > Voltage 115
> > Phase 1
> > Amps 2.15
> > Inlet/Outlet Flanged
> > Housing Material Cast Iron
> > Face to Face Dimension (In.) 6-1/2
> > Max. Temp. (F) 230
> > Max. Working Pressure (PSI) 145
> > Flange/Union Included No
> > Shut-Off (Ft.) 32
> > RPM 3000
> > Impeller Material PES Composite
> > Shaft Material Aluminum Oxide Ceramic
> > Thermal Protection Auto
> > GPM of Water @ 1 Ft. of Head 33
> > GPM of Water @ 2 Ft. of Head 32
> > GPM of Water @ 3 Ft. of Head 31
> > GPM of Water @ 4 Ft. of Head 30
> > GPM of Water @ 5 Ft. of Head 29.2
> > GPM of Water @ 6 Ft. of Head 5
> > GPM of Water @ 7 Ft. of Head 28
> > GPM of Water @ 10 Ft. of Head 25.4
> > GPM of Water @ 13 Ft. of Head 23
> > GPM of Water @ 15 Ft. of Head 21.5
> > GPM of Water @ 20 Ft. of Head 17
> > GPM of Water @ 25 Ft. of Head 12
> > GPM of Water @ 30 Ft. of Head 5
> > Length (In.) 6-1/2
> > Width (In.) 4-1/8
> > Max. GPM @ Head (Ft.) 33 @ 1
> > Best Efficiency GPM @ Head (Ft.) 12 @ 18
> > Min. GPM @ Head (Ft.) 12 @ 25
> > Drive Type Direct
> > Bearing Type Carbon/Thrust
> > Mechanical Seal Wet Rotor
> > Manufacturers Warranty Length 2 Years
> > Includes Flange Bolts And Gaskets
> >
>

Reply | Messages in this Topic (11)

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