ENH 325 Lecture Notes - Lecture 12: Double Check Valve, Sewer Gas, Back Pressure
4 May 2016
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Document Summary
Public supply goes in, private supply comes out. Two purpose for a plumbing system: provision of potable water and the elimination of waste. Potable water suf cient water no opportunity for back ow. Cross contaminations= back ow =back siphonage or back pressure. Back siphonage- vacuum breaker is downstream from the valve. Air gaps are the best way to prevent back ow. if there are air gaps it means you have no cross connections. The non-potable side pressure builds up and reverses the ow through the piping system. Or the reduced pressure zone back ow preventer- 2 valves and they are spring loaded. As the water goes through it lifts the springs. If the ow is reversed the spring prevent back ow. If pressure builds up the rst two valves should shut. If both valves fail and there is enough pressure to push backwards c should open and release to the atmosphere.
