A Quick Exhaust Valve, also known as a Quick Release ValvePilot Valve, Back Pressure Valve or simply, a QEV/QRV/BPV is a type of Valve designed to open a port in a pressurised chamber when one area is "exhausted" or released/vented into the open air.

A QEV typically conists of a spring, piston and a metal T-piece connected to the air source, the barrel and the exhaust chamber. The exhaust of which, is behind the barrel acting as the trigger.

  • ORANGE: Barrel
  • YELLOW: Piston
  • GREY: BB
  • DARK GREY: Spring
  • DARK BLUE: High Pressure Air
  • MEDIUM BLUE: Ported air power to BB
  • LIGHT BLUE: Vented lower pressure air
  • LIGHT GREY WHITE: Press valve


The Press valve (trigger) is pulled. This vents high pressure air out of the firing chamber. As the lower pressure air escapes on the right of the piston, the sudden drop in pressure pushes the piston backwards opening the barrel to the rest of the air inside the T-piece firing the BB.