NATIONAL FIRE PROTECTION Association 1901, Standard for Automotive Fire Apparatus, requires each pumper have a “pressure control system,” an integral safety feature to the fire pump system, which for our purposes includes the pump and its discharge outlets. The discharge pressure control system prevents dangerous/excessive pressure rises to protect fire service personnel from injury.

The automatic pump pressure governor (APPG) changes the engine speed to control pump discharge pressure. With modern electronically controlled engines, the pressure governor throttles the engine to speed up or down to maintain the pressure set by the operator.

Most modern fire apparatus around the world use centrifugal fire pumps. Generally, at the same engine speed, as discharges open and flow increases, the pressure goes down. In pressure-control mode, the governor increases engine speed to maintain the pressure; when discharges close and flow decreases, it reduces engine speed to maintain discharge pressure.

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