Fisher™ 644 and 645 Actuators

Fisher 644 and 645 actuators are used to automatically control steam-driven boiler feedwater pumps (reciprocating or turbine). The 644 or 645 actuator, when used in combination with one of several push-down-to-close sliding-stem valves, forms a pump governor. 644 and 645 actuators may also be combined with push-down-to-open valves to be used as relief governors.