If your fire fighting water pump is too small, it could cost your department a lot of money. But if it is too big, it might not be able to deliver the needed firefighting flow rate. The goal is to find the “sweet spot” like Goldilocks looking for the perfect bowl of porridge or the best bed to get a great night’s sleep.
In order to determine what fire fighting water pump is the right size for your facility, it is important to know a few things about both the GPM and the PSI of a firefighting water pump. GPM is the total amount of water that a fire fighting water pump is capable of moving in a certain time (usually given in gallons per minute) while PSI is the amount of pressure that the fire fighting water pump can generate, usually given in pounds per square inch (psi).
What causes your fire protection system to require a fire fighting water pump? A common reason is that the hydraulic design of a building’s water supply system cannot meet the flow and pressure requirements for the sprinkler or standpipe systems. Another reason is that the hydrant-flow test results do not meet the required pressure, typically 65 psi static and 40 psi residual when flowing 500 gpm.
When selecting the correct size fire fighting water pump for your facility, it is important to remember that a larger pump will also have higher installation costs, more supporting equipment and electrical service power requirements. In addition, larger pumps are more susceptible to cavitation and the associated damage and downtime that can occur when water vapor pockets form in the pump. These pockets can impinge on the pump’s components causing them to fail, which can increase maintenance and operational costs.