We have a newly-installed electric (duty) fire pump, and a back-up diesel fire pump.
Each pump has a 100% required flow capacity for the system (750 gpm each) for the building. Is it OK to run the two pumps simultaneously during testing - which would result in a 200% flow? The diesel pump is only intended to be used during power interruption/worst-case, but not with normal power online. During testing, we release water in the test line (flow meter) - the pressure went down and triggered the cut-in pressure of both the electric and diesel pump which makes it run simultaneously (electric first, then the diesel a few seconds later). Does this not have a water hammer effect on the system? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
10 Comments
Glenn Berger
2/3/2022 08:11:17 am
It is not okay to run both 100% pumps concurrently.
Reply
Casey Milhorn
2/3/2022 08:23:41 am
Agreed. Not a good idea. Each pump should be disabled during the other test run. Each should have a check valve, but still not a bad idea to shut off main control valve on discharge side of the non-testing pump as well.
Reply
Pete H
2/3/2022 08:28:02 am
I'm inclined to agree with Glenn, this does have elements that will potentially lead to issues where your system is not built for this massive 200% flow.
Reply
Nick Devine
2/3/2022 08:30:42 am
For an arrangement like this, I believe each pump is required to be flow tested independently to confirm their individual performance. It may be necessary to isolate the pumps from each other while performing testing by either disconnecting from power or by closing valves. Sometimes easier said than done, depending on impairment procedures.
Reply
SCHULMAN
2/3/2022 09:07:59 am
I am not sure why you would simulate a condition that would / should never happen in a properly installed system.
Reply
Jesse
2/3/2022 09:34:26 am
I think this falls under the "just because we can do it, doesn't mean we should". No, this isn't a good idea. Each pump should be tested independently.
Reply
Franck
2/3/2022 10:08:30 am
If the question is : is it a good idea to test both pumps simultaneously, then the answer has been assessed above and the answer is : no.
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Joshua Freedman
2/3/2022 10:40:54 am
I am just agreeing with what everyone else said. I would be very worried about causing supply pipes to collapse with suction dropping as low as I would imagine it could get with both running.
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Robert Hughes
2/3/2022 11:11:48 am
I'm no electrician, but I'd say your transfer switch should not allow the diesel pump to automatically kick on anyway without a power loss, either real or simulated.
Reply
Jack G
2/3/2022 04:45:44 pm
I disagree with Pete—- agree with Robert.
Reply
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