A fire pump is usually a part of a large building sprinkler system and is connected to the fire protection water supply at the intake, and to the building’s sprinkler system risers at the discharge. The fire pump provides additional water pressure to the sprinkler system. The fire pump starts when the pressure in the fire sprinkler system drops below a threshold. The sprinkler system pressure drops significantly when one or more fire sprinklers are exposed to heat above their design temperature. Fire pumps are needed when the local municipal water system cannot provide a sufficient pressure to meet the hydraulic design requirements of the sprinkler system. This usually occurs if the building is very tall, such as in high-rise buildings or in systems which require a relatively high terminal pressure at the fire sprinkler in order to flow a large volume of water, such as in storage warehouses.
Pre-action systems employ the basic concept of a dry pipe system in that water is not normally contained within the pipes. The difference, however, is that water is withheld from the piping by an electrically operated valve known as a pre-action valve. Valve operation is controlled by independent flame, heat, or smoke detection.
A deluge system is like a pre-action system except the sprinkler heads are open and the pipe is not pressurized with air. Deluge systems are connected to a water supply through a deluge valve that is opened by the operation of a smoke or heat detection system. The detection system is installed in the same area as the sprinklers. When the detection system is activated water discharges through all sprinkler heads in the system. Deluge systems are used in places that are considered high hazard areas such as power plants, aircraft hangars and chemical storage or processing facilities. Deluge systems are needed where high velocity suppression is necessary to prevent fire spread.