Operating the Pressure Relief Valve on the 4.4

When operated correctly, the pressure-relief mechanism prevents sudden increases in pressure being transmitted to the branch operator.

4.4 Pump Control Panel
4.4 Pump Control Panel

The following instructions refer to operation at the fire shed prior to go to a fire without hoses in operation:

1. MASTER PANEL – turn on switch.
2. PTO – turn on switch.
3. TANK TO PUMP – turn on switch.
4. Ensure Pressure Relief Value hand wheel is fully wound in (as far clockwise as possible)
5. Increase throttle to the required pressure on pressure gauge (10-12 bar maximum).
6. Turn hand wheel slowly anti clockwise until the relief value opens. the indicator light will illuminate, pressure gauge drops in pressure.
7. Reduce throttle to minimal rev’s.
8. Turn hand wheel two turns clockwise.
9.  Increase throttle speed to 2000 rpm, or just above, and check pressure gauge does not exceed desired setting. (The Relief Valve is now set to the required pressure.)

If at the fire ground and hoses are deployed:

1-6 as above
7. Turn the hand wheel clockwise until the pressure gauge rises to the desired pressure and the light goes out.

1. If the Rev gauge goes over 2000 RPM when trying to achieve 12 Bar pressure, there is a possible pressure build up. Stop the pump fully and release
pressure in the Black Hose Reel, then re- commence the above procedure.
2. When the Pressure Relief Value is fully wound in, water pressure is possible through the black reel hose lines but it needs to be reset for the monitor and red flat line hoses.
3. After vehicle use and pump is no longer in operation leave the pressure Relief Valve fully wound in. (Clockwise direction.)