All compressors, even small little portable units, require a compressor check valve in order to operate effectively and efficiently. These check valves, like other types of check valves, are completely automatic and they do not require any type of manual operation, electronic or pneumatic power to run.
Instead, the compressor check valve is designed to work based on the pressure differential between the two sides of the valve, as well what is known as the valve cracking pressure. The cracking pressure is the pressure on the inlet side of the valve that pushes the valve open and allows the flow of compressed air from the tank or the compressor once the specific internal pressure is reached.
Reciprocating Piston Compressors
On some types of compressors, such as those that operate using pistons to compress the air, two compressor check valve systems are found on each piston to allow air into the chamber when the piston drops down, but also to prevent air from escaping back down the inlet tube when the piston rises. Instead, the compressed air goes out through an outlet check valve, and this valve prevents the compressed air from being pulled back in when the piston drops again.
The Tank and Hose
A compressor check valve is also typically found between the pressure tank and the hose that goes out to the tool or the system. This valve prevents the compressed air stored in the tank from leaking out to the lower pressure of the hose once the compressor is stopped.
Without these valves, the compressor tank would simply continue to empty when the system was shut down. This would also allow any water or debris in the hose, pipe or tube to be pulled into the tank and into the compressor, leading to a greater risk of damage and system failure.