How to Adjust for Fire Pump Test Hose Elevation?

9/19/2019

I wonder if you could help me with this we tested a fire pump last week using mini hose monsters. The hose monsters were at an elevation 46’ higher than the pump outlet.

Are there any calcs that I need to do to get an accurate test?

In elevation this is a 20 psi loss plus 130’ of piping to reach the test header (one size larger than required) 8” for a 1000 gpm pump. Any help would be appreciated.

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4 Comments

Dave Sornsin

9/19/2019 11:55:21 am

Were you able to flow 1000gpm and (ideally) 1500gpm from the hose monsters?

pjd

9/19/2019 09:39:56 pm

Pressure losses on the test header path don't calculate into your pitot readings. Those readings are experimental data used to determine how much water is flowing...at that point. The sum of your head loss and friction loss should be added to your discharge gauge pressure when you are flowing at rated flow and at 150% rated flow. That's assuming you're able to get to 150%. If the pump is operating as designed, when flowing the rated flow through the play pipes, the discharge gauge will read lower than the rated pressure. That difference should be roughly in line with the sum of your losses along the test header path at that flow rate. If you suspect degraded performance I would compare the theoretic Hazen Williams difference with the experimental difference.

ioan rincu

9/20/2019 11:18:56 am

You don't need that.
When you test a fire pump all you are interested about is if it runs to 150% of the rated flow which you reach at 65% of the rated pressure. This is for all fire pumps! No psi's or gpm's, just percentages.
And of course you have to see if the rated pressure covers the gap between the system's pressure and the water source's pressure.
You also have to visualise (on the graph) where your point falls.
You may get 150% of the rated flow but only at 65% of the rated pressure and you may not cover your pressure gap. So it's a trade off.

Bobby

9/20/2019 11:50:13 am

My opinion:
If we are referring to an NFPA 20 pump test and not nfpa 14 standpipe test; The only reason to measure pressure remote from the pump i.e. at the hose monster is to confirm your GPM flow according to the hose monster charts. Otherwise the pressure for a pump test should be measured at the discharge flange of the pump where there should already be a pressure gauge port. So confirm the gpm flow is occuring at the appropriate test outlet wherever its at and then verify the discharge pressure at the pumps discharge pressure port.

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