4-18. PUMP, PIPING, AND VALVES - Continued
With the valve installed in the truck, start the fire pump in the structural mode, see para. 2-11.
With no hoses open, screw in engine throttle until pump outlet pressure approaches 270 psi (1860 kPa).
While watching the pressure relief valve discharge, continue to increase pump speed up to a maximum
of 275 psi (1900 kPa).
Reduce throttle and shutdown the pump, see para. 2-11.
Replace valve if valve does not relieve at set pressure.