When the air pressure in the chamber under valve member 1 exceeds a preset value, member 1 is lifted, compressing helical spring 2 and connecting the high-pressure chamber to the atmosphere. When the pressure in the system is below atmospheric, air flows through holes 3, acting on disk 4 and compressing spring 5, and enters the system, raising its pressure. Springs 2 and 5 are regulated by nuts 6 and 7.
$3616$SHP,Va$