Annual Fire Pump Flow Test Results, Do I have a Problem??

[Insurance Engineer]

A sprinkler contractor flow tests a fire pump at a large hospital.

Pump rating data of fire pump: Churn: 88.7psi, 1500 gpm @80 psi, 2250 gpm@ 68.6 psi

Here is what was on the test reports:

2010 Pump Test

Discharge Pressure

176, 181, 177

Suction Pressure

84, 115, 153

Net Pressure

72,66,24

Flow GPM

0, 1500, 2250

2009 Pump Test

Discharge Pressure

160,175,175

Suction Pressure

75,110,155

Net Pressure

85,65,20

Flow GPM

0, 1500, 2250

This is what NFPA 25, 2008 says

8.3.5.3 The fire pump assembly shall be considered acceptable if either of the following conditions is shown during the

test:

(1)*The test is no less than 95 percent of the pressure at rated flow and rated speed of the initial unadjusted field acceptance test curve, provided that the original acceptance test curve matches the original certified pump curve by

using theoretical factors.

(2) The fire pump is no less than 95 percent of the performance characteristics as indicated on the pump nameplate.

****************************

8.3.5.4* Degradation in excess of 5 percent of the pressure of the initial unadjusted acceptance test curve or nameplate shall require an investigation to reveal the cause of degraded performance.

***************************************

The pump graph with the report graphs the discharge psi, suction psi and ***** psi. It does not graph the net pump pressure and gpm. The pump test report does NOT list the Churn rating of the pump OR the 150% psi rating of the fire pump.

So what do you think?? Do I have a problem??

 

[Marshal Chris]

What about the voltage amperage and RPM readings?

How is the suction pressure going up when you're drawing more water?

The discharge pressure noted, is that on the pressure gauge on the pump or is that the pitot from the hose monster or similar device?

 

[Marshal Chris]

Just to add, I wouldn't accept it just based on the numbers. I'd want to see the pitot reading from each discharge point and know what size orafice they used so I could quickly run the numbers.

 

[Insurance Engineer]

I NEVER trust a contractor pump graph I always plot them myself

 

[FM William Burns]

Yes, but we have to love the 5% buffer and term "theoretical factor" allowing for real world changes in distribution systems after install dates and acceptance. In the event the degraded performance is not a simple identified issue like imbalance, obstruction or partial closing of an upstream valve, rarely are improvements made to actually bring supply back to what was completed years ago on the acceptance for or on a municipal distribution system without redundant supply tanks.

 

[Frank]

A-- Are municipal pumps in the water supply kicking in when sensing increased flow to explain the increase in suction pressure?

B-- Is there a main pressure relief valve set in the vicinity of 175 psi?

C-- If so does it discharge back to the pump suction line?

If conditions (A or C) and B exist it would explian these numbers if the flow is measured past the PRV. Then a lot more water would be flowing through the pump than is being measured.

I suspect it is conditions B and C.

 

[FyrBldgGuy]

Given the numbers why do you have a pump?

The increase in suction pressures indicates you have another pump or pressure regulating valve upstream of the pump you are testing. Your pump is doing more to induce loss into your system then ***** the pressure. Maybe if your RPMs were higher you could actually ***** pressure. But then your fire pump is based on a set RPM. If you have a Pressure Reducing Valve downstream that feeds back to your suction then you have a design problem.

Have you done a full flow test? Not just an inline flow meter back to your supply side, but a real test header with playpipes?

 

[peach]

well, I didn't stand in the water today, but I did verify the RPM readings on the pump.. the flow rate from the play pipes (why are they called that)?

Recommended better ventilation.. it was a diesel pump...

 

[Insurance Engineer]

The pump was retested this time by flowing water via a test header NOT via the flow meter.

Discharge Pressure

156,153,110, 84

Suction Pressure

68,65,26,10

Net Pressure

88,88,84,74

Flow GPM

0,760,1520,2003

After a lot of digging we found the last time the pump was flow tested via a test header was 10 years ago! They have been using the flow meter for all of the flow tests. NFPA 25 says max of 3 years between flow test vs. flow meter.

The pump did not reach 150% flow because of a poor water supply, note suction was 10 psi at 2003 gpm. BUT the pump can meet the sprinkler and standpipe demands which is OK by NFPA 25.

So like I said just because the contractor did the pump test does not mean it was done correctly and or the pump really worked. You have to question what you get and make your own evaluation.

 

[FM William Burns]

Here is a nice tutorial I found from another forum that some may like. It's a large file and may take a bit of time to download but it has some great information for anyone reviewing or witnessing acceptance testing: (Enter the code and click download) it's a (*pdf) so you can save it and create a checklist of things to verify if so desired.

http://www.megaupload.com/?d=EEAJZKWO