Answer: According to the function, there should be multiple check valves on the machine. There is a check valve between the main engine exhaust pipe and the oil separator, and the pressure maintenance valve also has a check function. The former prevents oil from flowing back into the main engine after the machine is shut down, and the pressure maintenance valve prevents external pressure from flowing back into the oil fine separator or the main engine. Secondly, a check valve is also installed on the exhaust outlet pipe after passing through the cooler. Its function is to prevent the pressure air of the air main pipe from flowing back into the air compressor unit when the air compressor unit is shut down.
