Fire pumps are the lifeblood of fire protection systems. They can be electric, diesel or steam turbine driven. Each has advantages and disadvantages but the diesel engine fire pump is primarily used in facilities where there is a dedicated fire pump room on an exterior wall of the building such as warehouses, aircraft hangars or industrial buildings. The diesel engine fire pump is able to operate on a wider range of fuels than its electric counterpart.
The fire pump engine is cooled by pulling water from the floor drain and passing it through a heat exchanger to cool the engine during operation. This method is preferred by NFPA 20 as it does not require the installation of a casing relief valve, since the cooling water acts in the same way a casing safety valve would.
During testing, it is important to ensure the supply and discharge isolation valves are closed, that the water inlet pressure is at minimum 30 psi and that the hydraulic power unit is operating. Also, the battery electrolyte levels should be checked to see that they are adequate and that the engine block heater is functioning properly.
The fire pump driver, whether it is an electrical motor, diesel engine or steam turbine system, must be sized to meet the full horsepower requirements of the fire pump, even if this means it flows beyond the 150% duty point specified in NFPA 20. The diesel fuel tank must be sized per the manufacturer’s specifications, and it is recommended to be located inside the fire pump room.