Fire pumps can be driven by electric motors or diesel engines. The latter are often selected as drivers for fire pump systems when a reliable source of electricity or fuel cannot be guaranteed. Power outages, load shedding, hurricanes and other disasters can leave electric motors without their power and render them useless in the event of a fire. Diesel engine driven fire pump are designed for unattended operation and provide backup for emergency use in these types of situations.
There are a number of things that need to be carefully considered when selecting and installing a diesel engine fire pump. The fuel supply, combustion air, ventilation, operating environment and the engine cooling system all need to be properly sized and installed.
The engine should be fueled with diesel fuel that complies with the requirements of NFPA 20 and the manufacturer’s datasheet. In addition, the diesel fuel tank should be located in the fire pump room and be appropriately sized to maintain a constant temperature during full-load operation. In areas subject to freezing, the tank should be insulated and provided with dedicated fill, vent(s) and a visual and monitored fuel level gauge.
The system should be thoroughly inspected and tested on an annual basis. During the inspection, a technician should evaluate the status of all supply and discharge isolation valves. If any are found to be open, they should be closed. In addition, the technician should verify that the recirculation piping is functioning and is delivering water to the heat exchanger. If it is not, the engine will overheat and damage may result.