I'm looking at a few projects that have fire pumps and above-ground cylindrical storage tanks for fire protection.
Some projects I have seen have recirculation after the fire pump discharge underground and back into the storage tank. Frustrated I can't find much on this in NFPA 22 or elsewhere.
Is this part of a means for freeze-protection, or to keep the water from getting stagnant, or for pump testing (in which case I guess it would have to branch off from the flow meter)?
Or is it likely engineer preference? Is it a military requirement?
Thanks in advance.
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12/5/2022 07:05:18 am
Environment, reliability, and cost savings.
12/5/2022 08:22:14 am
Perfect answer, as usual :)
12/5/2022 05:52:31 pm
Hi Dan, what do you mean that the Clean Water Act doesn't allow you to discharge sprinkler water into a storm drain? Every main drain test and typical fire pump test (flowing water from the test header) discharges sprinkler water to a storm drain.
12/5/2022 05:55:46 pm
Please ignore my previous post.
12/5/2022 08:06:52 am
Dan hit it on the head. I've done several tank supplied systems recently and in areas that have a well provide the 'maintenance fill' and if you're not testing back into the tank you end up needing to call and pay for and coordinate with a water supplier every time you test the system. That is expensive and annoying.
12/5/2022 08:10:17 am
On projects that I have a water storage tank, I do recirc the fire pump test header back to the tank. In addition to the reasons that Dan mentions, returning water to the tank prevents flooding and damage to landscaping or others in the way of several thousands of gallon of water flow at a significant pressure.
12/5/2022 08:13:02 am
Seems everyone here beat me to it. I always design a re-cirq back to the tank for all the reasons listed above.
12/5/2022 08:20:57 am
In Europe, where we are not using test headers but test lines with flowmeter, they have always been designed that way. The main reason at that time was to save money. When you flow test your pump every week and up to 150% every year, you can save a lot of money.
12/5/2022 08:33:05 am
Hi, seems like everyone hit it on the head. Re-cirq back to the tank for testing purposes.
12/5/2022 11:30:08 am
Thanks all - I guess what I was trying to visualize is that instead of the test loop (though the flow meter) tying back to the immediate suction side of the pump as is typical, I gather it instead routes back to the tank itself,* not both.
12/5/2022 02:15:13 pm
You get 2 years of flow meter usage with no water discharge; the third year requires water flow not recirculation.
12/5/2022 04:00:53 pm
Gotcha. No way around the test header for the 3rd year, and for the other two, flow meter to tank recirc. (We would typically add a normally-closed valve before the test header hose valves).
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