The fire pump system can be driven by either an electric motor or a diesel engine. The diesel engine is generally a more reliable option due to the fact that it is not subject to the severe changes in conditions encountered by an electric motor. While an electric motor can fail from extreme temperature variations or overloading, a diesel engine driver will not suffer these types of failures.
In many fire pump systems the diesel engine is located in a room or fire pump building that is sprinklered per NFPA 20. This fire pump room must be able to maintain a stable temperature to allow for the proper operation of the diesel engine. This room should also be sized to accommodate the storage and refueling of the fuel for the diesel engine. The diesel fuel tank should be sized to contain one gallon of fuel per engine horsepower plus five percent for expansion and five percent for sump.
The diesel engine should be equipped with an automatic shutdown for overspeed, high engine temperature, low lube oil pressure and optionally at a low coolant level. Often times the diesel engine fire pump is equipped with a manual isolation valve, allowing the fire pump to be isolated from the rest of the diesel engine during inspections and annual tests. This allows the diesel engine to remain powered up with no load and provides a test to verify that all of the safety features work as intended. diesel engine driven fire pump