Fire pumps are perhaps the most critical single piece of fire protection equipment installed at a site. Just like people, fire pumps come in all shapes and sizes. Fire pumps are needed at sites where public water supply pressure is too low for sprinkler effectiveness or where there is no public water supply at all. In the former case, a booster fire pump is installed to boost public water pressure to increase sprinkler effectiveness. In the latter case, a fire pump is connected to a private water supply (storage tank, reservoir, lake, river, or other) to create water pressure needed for sprinkler effectiveness and fire-fighting efforts.
Most fire pumps are either diesel engine driven or electric motor driven; however, some of those manufactured before 1974 are gasoline engine powered or even steam engine driven (though this is very rare). Booster fire pumps are usually electric pumps, whereas diesel fire pumps are more common on private water supplies. The pumps range in size from 25 gpm to 5,000 gpm (or more) at pressures from 50 psi to 125 psi (or more). Some are vertical shaft turbine-type pumps, while others are centrifugal pumps. For reference, "NFPA 20, Stationary Pumps for Fire Protection" (1999 edition) gives the latest requirements and other information on fire pumps. Appendices A and B (not part of the NFPA 20 standard) give valuable tips on fire pump design, installation, testing and maintenance, including troubleshooting.