Blower Relief Valve Vacuum Capabilities Vacuum Preset Limit 220 in wc Outside Diameter 5.7 in Inlet Size 2 1/2 in Inlet Type NPT Compatible Manufacturer Part Number 2EPR9 2EPT1 Compatible Grainger Part Number 2EPR9 2EPT1 Maximum Operating Pressure 28 in Hg Minimum Operating Pressure 1 in Hg Maximum Operating Temperature 400 Degrees F Minimum Operating Temperature -20 Degrees F Overall Length 7.31 in