How Many Hose Valves for Fire Pump Testing?

10/6/2023

NFPA 20 dictates the number and size of hose valves according to the pump rating, but is there any specific requirement on how many are to be used during testing?

How is that determined?

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8 Comments

Anthony

10/6/2023 07:59:43 am

Should use one 2 1/2'' hose per 250 gpm.

Jesse

10/6/2023 08:07:43 am

All of them.

Since we base the number of outlets on the test-header for the rated capacity of the pump, all of them should be used. One 2.5" outlet per 250-GPM for the pump. So a pump rated for 750 will have 3, a 1,500 will have 6, etc.

PEter

10/6/2023 08:14:21 am

Not quite. NFPA 20, 2016 Table 4.27A specifies the number of hose valves. It is a common misconception that it for every 250 GPM of the pump a hose valve is provided. For example: 1,250 GPM, 1,500 GPM and 2,000GPM all require 6 hose valves.

In answer to the original question, there is no prescriptive requirement in NFPA 25 on how many hose valves you need to have open to meet the flow requirements to test the fire pump. Generally speaking, you would typically flow the number of hose valves present. However, if you can achieve the flow and pressure requirements through a smaller number of hose valves you have proven the pump is performing as required and that is the only requirement of the test in NFPA 25.

Glenn Berger

10/6/2023 08:17:43 am

The above answers are correct. But here is a slightly different answer - As you work your way through the required flow rates during the test procedure then more hoses / hose valves are required.

The basic reason is that you do not want the pressure drop in the hoses to become a factor and thereby strew the test results.

Mike

10/6/2023 08:51:27 am

As Peter mentioned above there is no explicit requirement. If you're using long hoses you'll want more valves to keep friction loss in the hoses in check etc. We actually had a client fire pump tested 1 year out and fail only to end up looking rather bad because our "big" test trailer with 6 outlets was in use elsewhere so they only used 3 outlets to test a 1500 gpm pump and it was creating excessive restriction. After some back and forth our tester went back out and tested with 6 hoses and lo and behold the pump worked fine. We had some other issues on that job but between those and the bad test I think we lost that customer which is disappointing to say the least.

Dan Wilder

10/6/2023 09:06:38 am

Interesting...maybe someone from NFPA 20 can chime in

Best guess based on some deep Friday morning googling...

Rule of thumb is 250GPM per 2½" hose valve (more inline with standpipe testing than anything empirical but I'm sure there is some paper out there explaining why) ...but to test a 1000 GPM pump at 150%, you'll need to push out 375GPM per hose valve....so there's that.

Second thing to consider is the range of the Pitot gauge being used. Ideally, the midpoint of that gauge is the most accurate but use of the gauge within the middle 50% is preferred so you may need to do some backwards math based on your available equipment.

NFPA 291 wants Pitot pressures above 10PSI when fire hydrant testing but has a much larger discharge allowance..

I've Cx'd pumps with just over half the provided hose valves (throttling at the individual valves) and others have required all of them fully open (throttling at the interior butterfly valve) and I could not tell you what the determining factor was...

Because of a past experience that involved on the fly math, a crappy internet looking at submittals and charts, with lots of eyes during a test that wasn't gong well, I make up a small excel spreadsheet with each point on the curve I'm trying for along with multiple variations of # of hose valves and their corresponding pitot pressures to provide the flow needed.

Franck

10/6/2023 10:14:59 am

You need enough to test the pump up to 150% of its nominal flow at least once per year.
As indicated above by others, one hose valve per 250 gpm is a rule of thumb to determine it.
The minimum test points should be churn, 100% and 150%. But if you can have intermediate points, especially in the range 100-150%, it is much better.

A solution to avoid this : replace the test header with a test line and approved flowmeter. Much easier and more accurate to perform tests (and less water consumption if the test line goes back to the water tank). We normally never use trst header in Europe.

CONNOR R

10/6/2023 10:33:16 am

It depends on the hoses and equipment that you bring. Each test device e.g. hose monster is calibrated to be used in a certain configuration, and with a certain length of hose. As long as you are using the equipment consistently and in accordance with the manufacturer's listed instructions, you are fine.

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How Many Hose Valves for Fire Pump Testing?

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