Thread size: 1/4 BSP; Discharge Pressure: 10 Bar/145 Psi; Shut Off Pressure: 5 Bar/72 Psi The pressure relief valves control and limit the pressure build-up in air compressor system by automatically opening and closing. If the pressure reaches above 10 Bar(145 Psi), it will discharge the air; It will shut off automatically when the pressure is lowered to a safe operating level 5 Bar(72 Psi). This air compressor pressure relief valve is a safeguard to protect the compressor from back pressure. It is mainly installed in small air compressor systems, gas storage tank, air receiver tank, and other related applications. Thread the pressure release valve into the manifold and use a wrench to secure (Add additional sealant if necessary) (Always depressurize.