How Are Fire Pumps Balanced?

4/20/2021

Do fire pumps typically come balanced from the factory for the desired flow and pressure?

I know they are supposed to, but (just like any other pump) is their balancing done similar to a regular pump to get the desired pressure so that the pump operates at its rated duty point? I am aware that many factors affect final pressure discharges (such as friction loss, etc.).

Have you ever seen pump manufacturers calibrate pumps to the desired flow/pressure in the field?

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5 Comments

Glenn Berger

4/20/2021 08:24:00 am

I have witnessed many factory tests for fire pumps. After installation, I have witnesses the installation testing and acceptance operations. In a super majority of the times, these tests ends up giving identical results. Less than a handful of times have there been a need to "alter" the pump characteristics to get the intended results. The cause for these alterations was mainly due to the water supply characteristics being different than previously tested. Hope this response helps in your scenario.

Dan Wilder

4/20/2021 08:55:48 am

Our pump rep has not field "field fixed" a new pump because the factory has been on point with sending out accurate curves vs field performance however, we have had underperforming pumps receive new impellers that were machined at his shop (changing the diameter) to bring back flows & pressures more inline with the original curve.

My experience is the pumps typically run a little over the performance curve to start, especially diesel pumps as they run lean during break in.

Franck

4/20/2021 09:14:48 am

Normally, for fire pumps there is no need for field adjustment.
They are designed according to specific initial conditions (flow and pressure) and bench tested to check their adequacy.
Once on site, they are tested again (field acceptance test) and characteristics are compared to the bench test.
There might be some differences, sometimes due to a difference of suction/discharge pipe, compared to the bench test, or elevation difference of the pressure gauge that is not always compensated. But these differences should be minimum.
If the pump need more field adjustment, it is mostly because of a poor design of the installation, not the pump (as it has normally been tested prior to the installation).

Robert karlin

4/20/2021 10:54:36 am

Perhaps many other types of pumps are optimized for performance, as they are used for more continuous duty applications. as we all know - Fire pumps are designed to meet a particular flow - for a particular event that may never occur, and run times are limited to ITM requirements in respect to the accepted install.

Phil W

4/20/2021 11:42:20 am

As above, but sometimes poor quality flow measurement devices and pressure gauges can cause you to see different results from the factory tests.

Wherever you have them, take pressure readings from the controller digital display.

Easier to eliminate the measurement devices as cause of incorrect performance before you start ripping out pump impeller!

For diesels, check your engine speed has been set per the design parameters (i.e what speed should the pump be spinning at).

For electrics, check your voltage drops are within tolerance

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