The pressure protection valve protects different parts of the pneumatic circuit, such as the braking system and air suspension. There are three types of pressure protection valve: those with or without backflow, and those with limited backflow.

The pressure protection valve is typically installed between the air reservoirs of the braking and suspension systems. The air flow direction from port 1 to port 2 (see arrow on valve) must be observed. In case of pressure loss on the port 2 side, the valve will close to retain pressure on the port 1 side. UN-R13 requires that, in the event of a failure in the auxiliary system, a minimum of 80% of the braking force is maintained. The usual closing pressure is 5.2 bar (80% of 6.5 bar).

Over the years, as more new systems have been installed on trailers, we have found new applications for this type of valve. For example, it can be used to secure pneumatic roller doors or to retain residual pressure in the lift axle below. For this application, install the valve in the opposite way to take advantage of the backflow valve function.