Questions about Pressure Vacuum Breaker

Discussion in 'Irrigation / Sprinkler Forum' started by sneakyflute, Aug 7, 2014.

  1. sneakyflute

    sneakyflute New Member

    Aug 7, 2014
    Can someone explain the functions of the poppet and air inlet? I've done some research but I still don't quite understand what they do.

    Also, there are no leaks in my backflow preventer but I noticed that the poppet on mine is fixed in one place and doesn't spin like I've seen in some videos. Does that mean it's stuck or is that normal?
  2. Smooky

    Smooky In the Trades

    Apr 4, 2011
    North Carolina
    When the PVB is under pressure the poppet is stationary. The poppet is held up by the water pressure. If the water is shut off and the water is allowed to drain the poppet will drop down. The poppet covers an opening and when the poppet falls down, air can enter the PVB. When there is a loss of pressure and water is draining backward or forward it forms a vacuum in the line, the poppet drops and allows air into the system and this stops the vacuum and prevents contamination from entering the system.
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