Buffer Box

The Evac Buffer Box is a component that receives waste water from fixture drains. The buffer box is one of the key components that comprise an Evac riser along with an activator, interface valve, BVP valve, mini-check valve, and vacuum hose.


  • Receiving and holding waste water
  • Metering quantity of water per discharge cycle
  • Sending a signal to activator
  • Provides an atmospheric air intake for discharge cycle
  • Prevents backflow into refrigerated cases in the event of system malfunction


When waste water from a hand sink or a refrigerator display case enters the buffer box, the water begins to fill the buffer box and creates a head pressure in the activator sensor line. When the head pressure has built to the preset level, the activator opens the interface valve and air pushes the water up the riser and through the valve into the pipe network. It is sized so that it can handle the intermittent heavy flow generated during a wash-down of a display case (flow rates up to 6.0 gpm).

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