What is the primary purpose of the fire pump governor on a diesel-powered apparatus?

• A. To monitor engine oil temperature and trigger alarms.
• B. To regulate water flow at the nozzle regardless of demand.
• C. To maintain a prescribed discharge pressure by automatically adjusting engine speed as hydraulic demand changes.
• D. To prime the pump automatically.

Answer: (C)

The main concept is maintaining discharge pressure by modulating engine speed as hydraulic demand changes. The fire pump governor watches the system pressure and automatically adjusts the engine RPM to keep the set discharge pressure. When more outlets are opened or friction losses rise, the governor speeds up the engine so the pump can deliver more water and restore the target pressure. When demand drops, it reduces engine speed to prevent overpressure and to save fuel. This keeps the pump operating along its performance curve and provides firefighters with a stable, usable pressure. It isn’t primarily about monitoring engine oil temperature, nor about forcing water out regardless of demand, nor about priming the pump automatically.