Compressor valves are valves used within a compressor to allow gas flow to and from the cylinder area. They operate based on pressure difference: if the pressure below the valve is greater than the pressure above plus the spring force, it opens. The valves function as spring-loaded non-return valves, with the gas only being able to flow in one direction.
Compressor valves are circular and consist of a series of plates or rings sandwiched between the valve seat and cover. When a pressure difference occurs, the rings or plates are pulled toward the area of greater pressure and use springs to return to their closed position when pressure normalizes. Even when used in lower-speed compressors, these valves may routinely open and close more than 1 million times per day and are often constructed of durable precision materials to compensate for this workload.
Two types of compressor valves: a plate valve (left) and ring valve.
Image credit: Belphie