We have a project and have gotten into an internal debate. The project has four diesel fire pumps in one pump house.
During testing, are we allowed to run all four at the same time? Or do we need to run each separately as we do normally to reduce the chance of blowing out a main? Anyone have insight on this? Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
15 Comments
Pete H
1/26/2024 06:43:27 am
No actual idea, but my two cents/hazarded guess is if there's a chance they could be run simultaneously in a hazard condition, run them simultaneously because you'll want to know if the main blows out in such a case now during testing.
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Pete H
1/26/2024 06:43:56 am
why risk blowing out*
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Dan Wilder
1/26/2024 07:51:06 am
Going to need a little more info:
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Alex
1/26/2024 08:05:29 am
On a quick review, what is your main size and that are the sizes of the four pumps? When each is flowing 150%, what is your total expected flow?
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José Garcia
1/26/2024 08:27:46 am
Assuming that the pumps are in parallel, it is known that the flow rate increases four times, but the discharge pressure remains constant, whether activating one pump or all four. There is no possibility of overpressurizing the system. It is also important to remember that the discharge flow rate is limited by the diameter of the discharge pipe.
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Franck
1/26/2024 02:39:42 pm
Fully agree !
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Jesse
1/26/2024 08:45:43 am
Short of saving some time, what's the reason behind the intent to run all 4 simultaneously?
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Sunil Kumar
1/26/2024 09:05:37 am
Dear All,
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Dwight Havens
1/26/2024 09:53:01 am
A lot of good comments here. Dan Wilder's covers my experience.
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Glenn Berger
1/26/2024 10:29:05 am
For testing purposes, NFPA 20 is clear that if multiple pumps are required to meet the flow demand, then you need to have the correct number of pumps running. Just do not start the pumps simultaneously; but start them in proper sequence.
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Franck
1/26/2024 02:37:08 pm
You only need to test all pumps simultaneously if they are required simultaneously for the maximum demand at the plant. And if you want to check it once.
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Mark Harris
1/26/2024 04:48:25 pm
Several years ago had a project at an Oilseed Extraction plant that had large deluge systems and multiple pump pump house supplied from tanks. As I recall four diesel and two electric. Annual test of the pumps were individual but they had a fire and the deluge demand started multiple pumps and they ran for extended period. With all the diesel pumps running we found out the pump house did not have adequate fresh air intake to supply the diesel engines. Something we don't always think about but it is part of the NFPA 20 design. Think got information form Cat engines to help with analysis later as well. As far as flow and pressure everybody above has that well covered.
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Radhakrishnan Duraikkannu
1/28/2024 05:47:23 am
For Routine Test, each diesel engine pump set can be done individually. For maximum water demand test , the proposed main pumps only (out-of 4 diesel engine driven) pumping capacity need to run all th emain pumps.
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RYAN HINSON
1/29/2024 05:02:34 pm
NFPA 20 (2022) Section 14.2.6.3.3.1 - "Where simultaneous operation of multiple pumps is possible or required as part of a system design, the acceptance test shall include a flow test of all pumps operating simultaneously."
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Drew K
2/5/2024 09:03:13 am
The first question to ask yourself is can the city supply main provide the anticipated volume for all pumps running simultaneously? From your design flow test is Q20 within test parameters? Don't try to flow more water than you have available. If the system requires more than the city can provide then you may need to consider a storage tank.
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