Evacuation valves

Fig 1: Evacuation Valves

Courtesy of VOLVO CARS OF NORTH AMERICA.

The evacuation valves are used to even out the pressure in the passenger compartment.

The rubber dampers in the evacuation valves open when the air pressure is slightly higher in the passenger compartment than outside. When the air pressure is the same on the inside and the outside, the rubber dampers close. This prevents water and air (odors, dust and exhausts fumes) from penetrating the passenger compartment.