Rogers-Grove-interior



Backflow Assemblies & Methods

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Types of Backflow Assemblies

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1. Reduced Pressure Principle Assembly (RP)

Used on health hazards in buildings and is a combination of check valves and an air inlet allowing water from the private system to vent when City pressure drops.

Requirements

  • 1 foot above the floor
  • No higher than 5 feet
  • Adequate drain
  • Adequate protection from vandalism if outdoors
  • Protect from freezing

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2. Pressure Vacuum Breaker (PVB)

Mainly used for irrigation. It has a one way check and a spring loaded air inlet valve that closes when City water main pressure drops.

Requirements

  • No backpressure
  • 12" above high point of use
  • Adequate protection from vandalism if outdoors
  • Protect from freezing

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3. Double Check Valve Assembly (DCVA)

Typically used on non-health hazards in buildings and on fire lines. It uses two spring loaded valves.

Requirements

  • 12" above the floor
  • No higher than 5 feet
  • Protect from freezing

4. Atmospheric Vacuum Breaker (AVB)

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Used mainly on irrigation systems. It has an air inlet valve that will drop to draw in air thus preventing sprinkler system water from entering the City's water mains.

Requirements

  • Not under continuous pressure for more than 12 hours
  • No downstream valves
  • No backpressure
  • Six inches above high point of use
  • Protect from freezing


Types of Backflow Methods

1. Air Gap

Used mainly on tanks and faucets, it is a gap between the pipe and the container.

Requirement

  • The gap needs to be a minimum 2 times the supply pipe diameter
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