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Firefighting Pump Npshr Not Mentioend As Per Fm/ul?


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#1 N243

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Posted 17 September 2019 - 03:41 AM

Hi everyone,

 

I have a peculiar situation which I am facing currently and hoping experienced people here can assist me.

 

I am evaluating a flooded-suction type firefighting pump proposal in which the vendor has declined to mention the actual NPSHr required.

 

Upon enquiry, their response can be boiled down to "It is FM/UL Certified and hence, the NPSHr is meeting FM/UL Guideline." 

 

I dug deeper and found out that FM refers to NFPA 20 for sizing/guideline but nothing has been mentioned regarding NPSH for a centrifugal diesel-driven engine pump.

 

Has anyone here faced a similar situation and is NPSHr not mentioned for FM/UL certified pumps?

 

-N243



#2 PhilippM

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Posted 17 September 2019 - 03:51 AM

Can't you just state the available NPSH in the specification and then require the vendor to verify that the pump will be able to meet this specification if he wants to sell his pump?



#3 breizh

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Posted 17 September 2019 - 04:45 AM

https://www.stevenbr...es.com/faqs.php

Hi,

Let you take a look at this document . As long your suction is always flooded there is no issue . Make sure you design the right priming pot .

Better to use a vertical pump if you take water from a pond to avoid issue with foot valve, in the past I had requirement from Insurance company

My view

Breizh 


Edited by breizh, 17 September 2019 - 07:35 AM.


#4 Shahzad Ahmad

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Posted 17 September 2019 - 06:24 AM

Hi everyone,

 

I have a peculiar situation which I am facing currently and hoping experienced people here can assist me.

 

I am evaluating a flooded-suction type firefighting pump proposal in which the vendor has declined to mention the actual NPSHr required.

 

Upon enquiry, their response can be boiled down to "It is FM/UL Certified and hence, the NPSHr is meeting FM/UL Guideline." 

 

I dug deeper and found out that FM refers to NFPA 20 for sizing/guideline but nothing has been mentioned regarding NPSH for a centrifugal diesel-driven engine pump.

 

Has anyone here faced a similar situation and is NPSHr not mentioned for FM/UL certified pumps?

 

-N243

 

As per NFPA 20, all fire pumps shall be FM or UL certified.

Normally, the vendors provide info regarding NPSH by providing NPSH curve of pump.

 

Regards,

Shahzad 

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#5 N243

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Posted 17 September 2019 - 11:45 AM

Hi, thank you all for the response.

 

@PhilippM

Our NPSHa itself is very low and we are thinking of adding in booster pumps just to elevate the NPSHa. Hence, you can see that we require NPSHr for the firefighting pump to make a decision on it. Ideally, the proper approach would be to finalize the NSPHa before going for procurement, however, we have faced multiple design changes before due to cost implications and addition of other auxiliary equipments.

 

@SAK...

Usually they would publish the NPSHr in the pump curves as well but this time they haven't. Your Input is appreciated all the same.

 

@breizh

Thank you for the link. I have gone through it and arrived to the same conclusion as your statement. As long as I can achieve flooded-suction in my pump, then the pump should be able to prime itself for the designed flow. Maybe NPSHr is not a critical factor as opposed to pumps of non-flooded suction type. Correct me if I'm wrong in stating that.






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