Definitions

General Backflow Definitions

 

1. Air Gap Separation - Physical break between the supply pipe and flood rim of receiving vessel. Distance shall be at least twice the size of the supply pipe and in no case less than one inch. 


2. Aspirator Effect - Backsiphonage resulting from a reduction in pipe size or a restriction in the volume of flow.


3. Atmospheric Pressure - The weight of the atmosphere on the surface of the Earth. The atmospheric pressure at sea level is 14.7 psia.


4. Atmospheric Vacuum Breaker - A non-testable backflow preventer recognized for protecting against high hazards, but for backsiphonage purposes only. Consists of an air inlet valve intended for non-continuous use.


5. Backflow - The unwanted reversal of water flow in distribution lines. Backflow may also occur from gases or vapors from another substance or source connected to the potable water. 


6. Backpressure - Results when the downstream pressure becomes greater than the incoming pressure. Causes may include pumps, elevated piping, thermal expansion, etc.


7. Backsiphonage - A sub-atmospheric condition occurring in a water line resulting in the reversal of water flow.   


8. Double Check Valve Assembly - A testable backflow preventer designed for protecting against low hazards only. Consists of two check valves, two shut off valves and four test cocks.


9. Pressure Vacuum Breaker Assembly - A testable backflow preventer designed for protecting against high hazards. Consists of a check valve, an air inlet valve, two test cocks and two shut off valves.


10. Recycle Water - Black waste water that has been filtered and treated to meet a certain quality standard that is acceptable for its specific intended use. Two examples for its use would be for irrigation and cooling tower water makeup.


11. Readily Accessible - Means the backflow preventer is in a location that is easily accessible for testing and repair. The distance from the ground/floor to the bottom of assembly should not be more than five feet.


12.. Reduced Pressure Principle Assembly - A testable backflow preventer designed for protecting against high hazards. Consists of two check valves, two shut off valves, four test cocks and a relief valve.


13. Spill Resistant Vacuum Breaker - A testable backflow preventer designed for protecting against high hazards. Consists of a check valve, an air inlet valve, two shut off valves, a test cock and a vent valve.


14. Water Purveyor - The agency primarily responsible for providing quality water that meets the standards set by state and/or local rules and regulations.