The minimum pressure valve is a small accessory in the air compressor, but it is very important. It can generally be found on the top of a compressed air tank. The minimum pressure valve has two functions: 1. Open under a certain pressure to ensure that the air pressure is at a minimum value. 2. Prevent outside air from entering the air through the valve. This function is very similar to a check valve. The minimum pressure valve is rarely damaged, so maintenance is generally not required. It is recommended to replace the seal every several thousand hours. A good quality minimum pressure valve is very important.