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The City of Portland, Oregon

Portland Water Bureau

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Pressure Vacuum Breaker Assembly

The Pressure Vacuum Breaker Assembly (PVBA) is an outgrowth of the atmospheric vacuum breaker and evolved in response to a need to have an atmospheric vacuum breaker that could be utilized under constant pressure and was testable.

These assemblies may be used under constant pressure but do not protect against backpressure conditions. The assembly must be at least 12 inches higher than any downstream piping.

A diagram of a pressure vacuum breaker is illustrated below along with typical installation drawings:


Installation type:  Above ground
Safe to inject chemicals into system?  No
Okay to locate control valves downstream?  Yes
Okay to locate backpressure source downstream of assembly?  No
Installation height in relation to highest downstream piping:  12 inches above ground
Number of assemblies required: One per system
Use only with irrigation sprinkler heads?  Yes
Testing required after installation: annually
Testing required after repairing or moving assembly? Yes
Cost:  Varies