Fire pumps are used to boost the water pressure in sprinkler and standpipe systems and to deliver the required amount of water (Figure 3.5). This is necessary when the system is fed by a non-pressurized water tank, or when the water supply feeding the system has inadequate pressure. A fire pump may be driven by an electric motor, diesel engine, or steam turbine.
NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection, contains design and installation details for fire pump installations. NFPA 20 requires electrical monitoring of pump controllers for pump running, power failure, or controller trouble. These remote alarm signals are often incorporated into fire alarm annunciators, so that fire departments may identify the status of a given fire pump.
A fire pump controller is the enclosure that contains controls and status indicators for a fire pump. NFPA 20 requires these devices to be within sight of the fire pump motor or engine. The automatic transfer switch, which is often in a separate enclosure, transfers power to a secondary power source (when provided). Fire service personnel may need access to this equipment during the course of a fire.
NFPA 20 contains reliability requirements for the power supply to an electrically driven fire pump. For example, power supply lines must be protected and the circuit must be independent of a building’s electric service. The latter feature allows the fire service to shut down building power while the fire pump continues to run. 29 CFR Subpart S must also be followed.
The most desirable location for a fire pump is in a separate building. This affords the most protection from fire, and gives firefighters easy access to the pump and its controllers. If locating the pump in a separate building is not possible, a fire-rated room with an outside entrance is the next best option. NFPA 20 requires pump rooms to be separated from the rest of the building by 2-hour fire-rated construction in buildings without full sprinkler protection, and 1-hour construction in fully sprinklered buildings.
Inside and outside entrances to fire pump rooms should be labeled with signage. Minimum lettering size should be six inches high with a 1/2 inch stroke (thickness of lines in each letter).