Fire pump
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A fire pump is usually a part of a large building fire sprinkler system and is connected to the municipal water system at the intake and to the buildings sprinkler system risers at the discharge. A fire pump is listed specifically for fire service by a listing agency such as UL or FM Global. The main code that governs fire pump installations is the most recent edition of the National Fire Protection Association's (NFPA) NFPA 20 Standard for the Installation of Stationary Fire Pumps for Fire Protection.
Fire Pumps are usually powered by an electrical motor and may require the installation of an emergency generator. Other means of power are a directly connected diesel engine, or in rare cases, a steam turbine. Gasoline and natural gas engines have been prohibited sources of power since the 1974 edition of NFPA 20.
The fire pump becomes active when the pressure in the fire sprinkler system drops below a threshold. The sprinkler system pressure drops significantly when one or more sprinkler heads are exposed to heat above their design temperature. The sprinkler head releases and water discharges. The discharge of water triggers a water flow alarm inside the sprinkler system pipes, which is monitored by a central station and which the Fire Department responds to. The fire pump provides additional water pressure to the sprinkler system.
Fire pumps are required in high-rise buildings. They are also used in warehouses and facilities that do not have adequate city water pressure. In this case, a fire water tank is used. Types of pumps used for fire service include: horizontal split case, vertical split case, vertical inline, vertical turbine and end suction.
[edit] Jockey Pumps
In order to maintain adequate water pressure inside the sprinkler system a pressure maintenance or jockey pump is used. The jockey pump becomes active when the water pressure inside the fire sprinkler system dips below a higher threshold than the fire pump's threshold. The jockey pump is sized so it will compensate for pressure losses from small leaks, expansion and evaporation. The size (volume of flow) is kept under the demand of one sprinkler head so that the main fire pump will start when a sprinkler head is fused.
