Jockey pumps are small capacity pump which overrides main fire water pump (electric motor and diesel). Jockey pump is set such that it starts at low pressure in header and stop at high pressure to maintain the desire pressure in the network. Main fire water pump is set such that if the pressure drop to a very low value, it will start automatically but it can not stop in auto mode and it has to be stopped manually after human intervention.
Jockey pump plays a very important role in fire water network system. If there is small leak in any flange in the network, there is very small pressure drop in the network. In this stage main fire water pump should not start because its capacity and head is too high. In this condition jockey pump take care about the system. If there is some fire in the plant, sprinkler system will start. It will cause pressure drop in the fire water network. Jockey pump can not take care about such big pressure drop and at this stage there is a true requirement of main fire water pump. At this stage main fire water pump will start.
