Vacuum Relief Valves, Vacuum Flow ValvesRelief Valves for Regenerative Vacuum Pumps Model No.: VRV-1-EA Part No. Use with Vacuum Pump Model Number Overall Height in. (mm) Diameter in. (mm) Thread Size VRV-1-EA VB3HF, VB7HV,VB9HV 3.50 – 4.38 (88.9 – 111.3) 2.00 (50.8) 1″ NPT Male