A pressure vacuum breaker (PVB) is a type of
backflow prevention device, used to keep non-
potable
Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, a ...
(or contaminated) water from entering the water supply. A PVB is similar to an
atmospheric vacuum breaker An Atmospheric Vacuum Breaker (AVB) is a backflow prevention device used in plumbing to prevent backflow of non-potable liquids into the drinking water system.
It is usually constructed of brass and resembles a 90-degree elbow with a hood on it ...
(AVB), except that the PVB contains a spring-loaded
poppet
In folk magic and witchcraft, a poppet (also known as poppit, moppet, mommet or pippy) is a doll made to represent a person, for casting spells on that person or to aid that person through magic. They are occasionally found lodged in chimneys ...
. This makes it acceptable for applications that are high hazard or where valves are downstream. Pressure vacuum breakers must be protected from freezing when installed outdoors. PVBs usually have test cocks, to which specially-calibrated gauges are attached, in order to ensure that they are functioning properly.
Backflow prevention devices such as PVBs are regulated by the
Uniform Plumbing Code
Designated as an American National Standard, the Uniform Plumbing Code (UPC) is a model code developed by the International Association of Plumbing and Mechanical Officials ( IAPMO) to govern the installation and inspection of plumbing systems a ...
, but may also be required by government regulations.
See also
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Air gap
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Atmospheric vacuum breaker An Atmospheric Vacuum Breaker (AVB) is a backflow prevention device used in plumbing to prevent backflow of non-potable liquids into the drinking water system.
It is usually constructed of brass and resembles a 90-degree elbow with a hood on it ...
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Chemigation valve
Sometimes called a check valve or a backflow preventer, a chemigation valve is an apparatus designed to protect water supplies from agricultural chemicals used during chemigation, the application of chemicals such as fertilizers and pesticides t ...
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Double check valve
A double check valve or double check assembly (DCA) is a backflow prevention device designed to protect water supplies from contamination. It is different from the two-way check valves (sometimes erroneously referred to as double check valves) us ...
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Hydrostatic loop
A hydrostatic loop, though not often used in plumbing practice, is an arrangement of pipes formed into a vertical loop to prevent backflow of water within the plumbing potable water system. Since a siphon has a maximum height that it can work ( ...
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Reduced Pressure Principle BFP
A reduced pressure zone device (RPZD, RPZ, or RPZ valve) is a type of backflow prevention device used to protect water supplies from contamination. RPZDs may also be known as reduced pressure principle (RP), reduced pressure principle backflow ...
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Plumbing valves
Irrigation
Backflow