Atmospheric vacuum breaker

One-Inch Brass Atmospheric Vacuum Breaker mounted on PVC Pipe

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. A backflow Prevention Device is used to protect Water supplies from contamination or pollution Plumbing, from the Latin plumbum for Lead, is the skilled trade of working with pipes, tubing and Plumbing fixtures for Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of Water of sufficient quality to serve as drinking water is termed potable water whether it is used for drinking or not It is usually constructed of brass and resembles a 90-degree elbow with a hood on its top to allow air to enter the water system if a siphon attempts to form. Brass is any Alloy of Copper and Zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five A siphon (also spelled syphon) is a continuous tube that allows liquid to drain from a reservoir through an intermediate point that is higher than the reservoir the flow being Inside this elbow is a poppet valve that is held "up" by the water pressure found in the system, closing the air entrance to the device. A poppet valve is a Valve consisting of a hole usually round or oval and a tapered plug usually a disk shape on the end of a shaft also called a valve stem If the pressure in the "upstream side" is reduced to atmospheric pressure or below, the poppet valve drops and allows air to enter the system, breaking the siphon.

These devices, since they work on atmospheric principles, cannot be installed in an enclosure containing air contaminants. Air pollution is the human introduction into the atmosphere of Chemicals Particulate matter, or Biological materials that cause harm or discomfort As air is a fluid, those contaminants could be drawn into the device, thus fouling the pipes. For the various smoking devices see Hookah or Bong. For other uses see Pipe. The AVB should be installed at least six inches above the highest use downstream.

The AVB is for "Low Hazard" applications only and should not be used with continuous pressure on the device, as the poppet would likely stick and the AVB would no longer function properly. A shutoff valve should never be placed downstream of any AVB, as this would result in continuous pressure on the AVB. The AVB is not a testable device.

An air gap, as it relates to the Plumbing trade is the unobstructed vertical space between the Water outlet and the Flood level of a fixture A chemigation valve is an apparatus designed to protect water supplies from Agricultural chemicals used during Chemigation, the application of chemicals such as A double check valve or double check assembly (DCA is a Backflow prevention device designed to protect water supplies from contamination 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 A Pressure Vacuum Breaker (PVB is a type of Backflow prevention device,used to keep non- Potable (or contaminated water from entering the water supply A reduced pressure (RP Backflow prevention device is a device used to protect the Potable water supply from contaminated water

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