Which device maintains discharge pressure by adjusting engine speed in response to system demand?

• A. To monitor water temperature.
• B. To maintain discharge pressure by adjusting engine speed.
• C. To regulate output flow in gallons per minute regardless of demand.
• D. To start the jockey pump.

Answer: (B)

Maintaining discharge pressure by adjusting engine speed relies on a pressure governor. This device continuously senses the system’s discharge pressure and modulates the pump engine’s fuel or throttle to keep the pressure at a set point. When demand causes pressure to drop, the governor increases engine speed to raise output; when pressure is high, it eases back the speed to hold the pressure steady. This dynamic control lets the fire pump respond to varying demands and keep the discharge pressure within the desired range.

Starting the jockey pump is only about initial pressurization and reducing cycling of the main pump, not maintaining pressure through changes in demand. Monitoring water temperature doesn’t directly control discharge pressure, and trying to regulate output flow regardless of demand ignores the sensed pressure and leads to inconsistent system performance.