Table 2-1. Street Side Operator's Controls and Indicators
250 GPM Mini-Pumper Firefighting Truck (Continued)
(Refer to Figure 2-1)
Control or Indicator
Pressure Relief Control
The Pressure Relief Control Knob
is used to increase or decrease the desired pump operating pressure.
The relief valve functions to prevent excessive build-up of pump
pressure when a hose line is shut-off, by automatically bypassing the
extra water from the discharge side to the suction side of the pump. The
relief valve is capable of controlling pump pressure from 0 to 300 PSI.
Turning the pressure relief control knob to the left (counterclockwise)
decreases pump pressure. Turning it to the right (clockwise) increases
The Tank-To-Pump Valve Control
Handle is used to allow water to flow from the water tank to the pump.
To operate, pull the handle all the way out, allowing the water to flow
from the tank.
Push the handle in to close.