The fire water pump is the heart of any fire system, and it’s not to be taken lightly. There are many considerations when it comes to choosing a pump and system for any facility, including local regulations, and the decision should be made by a knowledgeable fire safety professional.
There are two figures that are crucial when selecting the right pump: PSI and GPM. The PSI is the pressure of the water, while the GPM is how much water is being put out per minute. The relationship between these is important to understand because if the GPM is increased, then the PSI will go down, and vice versa.
While many firefighters focus on the pressure of the firewater stream, it is not always what kills a fire. In fact, large fires often happen because the firefighting water is not put at the seat of the fire at the correct gpm. This means the fire officer has to determine how much water is needed and select the appropriate nozzle tip with the correct flow to extinguish the fire.
Another consideration is ensuring the pump has sufficient power reserves to perform at its rated capacity under load. This can be done by using the UL/FM listing process, which ensures the driver, or diesel engine, is properly sized for the fire pump. Another way to ensure this is by reviewing the certified factory test curves for both electric and diesel pumps, which show how they perform under load.