When doing an annual test today for large fire pumps with a combined test header, I was told that most inspectors throttle and send water to the pitot gauges by using the butterfly valve inside the pump room and keeping the control valves wide open outside on the test header.
I disagreed with this approach, as my mentor in the industry taught me to first charge the test header and then get your pressures by opening each outside control valve individually to get your pressures. He said this is so that you don't burn up the rubber on the inside test header (normally-closed) butterfly valve. He said it happened to him in the past and then the building owner is left with a leaking test header control valve and the danger and costliness of a test header full of water.
Is there a correct way (by code) to get your pitot reading off the hose monsters outside (what I mainly using) or is charging water one way or the other simply a matter of preference?
I hope this makes sense.
I understand some test header control valves are OS&Y but most all the outside components I come across are the test hose connections that open and close via the gate valve.
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3/1/2022 08:08:04 am
I've done tests both ways for years. I have never come across an issue by throttling via the butterfly valve. I don't believer there is a required procedure in NFPA 20 or 25 on how it should or shall be performed.
3/1/2022 08:17:19 am
I lost count of the number of butterfly valves I've had to replace over the years due to using the butterfly to throttle flow. Turbulence tears up the rubber seat that is on the vane, and it will no longer seal even after some times just one test. While there's no prohibition that I know of for doing this, it is very bad practice.
3/1/2022 08:27:23 am
3/1/2022 09:10:34 am
If you are looking to perform the test(s) at 0%, 100%, and 150% flow, the it is easier to use the throttling valve. If you are running the test with one hose valve open, two hose valves, three hose valves open, then the butterfly valve provides no assistance in this manner.
3/1/2022 01:08:47 pm
On pump commissioning, we leave the butterfly open and throttle via the hose valves. On yearly (or 3-year if a flow meter is installed), the inspections guys I have seen will use the butterfly valve. Doesn't help that these are normally closed valves (if order correctly and not wired backwards)
3/1/2022 01:36:35 pm
I have tested both ways. I will use the test header supply valve to throttle most times if its an OSY (older install) as opposed to the butterfly. I haven't had any issues with butterfly valves burning up, but I can see it being an issue.
James E. Art FPE, Ca
3/2/2022 11:59:54 am
Throttling using a butterfly va. is very difficult (and can be hard on the rubber parts.)
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