Backflow preventer with atmospheric vent

Plumbing · Distribution Piping In the House · printed page 268 (PDF page 269)

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Book index entries

Backflow Preventer – with Atmospheric Vent Backflow Preventer with Atmospheric Vent Supply Plumbing – In-house

Text in the illustration

Backflow preventer with atmospheric vent vent vent
normal operation
water
water flow
check valve (open)
vent
backflow condition
check valve (closed)
note: mechanism simplified for clarity

Generated explanation

Two sectional diagrams show a backflow preventer with two spring-loaded check valves and an atmospheric vent beneath the intermediate chamber. During normal operation, both check valves are open and arrows show water flowing from left to right. Under the backflow condition, an arrow shows water entering from the right, and both check valves are closed to block reverse flow. The vent connection is shown below the chamber in both diagrams. A note states that the mechanism is simplified for clarity.

Components

backflow preventer check valves check valve springs atmospheric vent intermediate chamber valve body supply pipe connections