This 1/4" MNPT safety relief valve is constructed with the same materials as ASME safety valves, but is not national board certified so they cannot be used on applications requiring ASME components. The non-coded valve is equipped with a lift ring for instant relief and is stacked at the factory at the pre set pop-off pressure. Has a pop-off pressure of 150 PSI. These valves are not for use on compressors with a capacity over 15 CFM, 3 HP or 12 gallon storage tank.