Breather valves are an essential part of a well-designed refrigeration unit such as refrigerated delivery trucks and vans, walk-in coolers, and refrigerated shipping containers. Differential pressures can develop in these sealed systems due to changes in temperature and the opening and closing of doors. These pressures can cause damage to hinges, door latches, and seals as well as make it difficult to open and close the door. The installation of one of our pressure-relief valves will help protect the system and make it easier to use.