Backflow Prevention & Cross-Connection Control Flashcards
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Read the first 7 Backflow Prevention & Cross-Connection Control flashcards as text
What is a cross-connection in a plumbing system?
Answer: Any physical link between a potable water supply and a potentially contaminated source
A cross-connection is any physical connection between a potable water system and a non-potable source that could allow contamination to enter the drinking water supply.
What type of backflow occurs when negative pressure develops in a supply line and draws contaminants backward?
Answer: Backsiphonage
Backsiphonage occurs when a drop in supply pressure below atmospheric creates a siphon effect that pulls contaminants back into the potable water system.
Which backflow prevention method provides protection solely through physical separation with no mechanical parts?
Answer: Air gap
An air gap is the only non-mechanical backflow prevention method, relying on physical separation between the water outlet and flood level rim to prevent contamination.
What is the minimum air gap required between a water supply outlet and the flood level rim of a receiving fixture under most plumbing codes?
Answer: Twice the effective opening of the supply outlet, but not less than 1 inch
The required air gap is at least twice the effective opening (diameter) of the water supply outlet, with an absolute minimum of 1 inch to prevent backsiphonage.
Which backflow prevention assembly is specifically required for high-hazard cross-connections to a public water supply?
Answer: Reduced pressure zone (RPZ) assembly
The reduced pressure zone assembly provides the highest level of mechanical protection and is required by code for high-hazard cross-connections due to its relief valve between two independent check valves.
What is backpressure as it relates to plumbing cross-connections?
Answer: A condition where downstream pressure exceeds the potable supply pressure, pushing contaminants backward
Backpressure occurs when a downstream system (such as a booster pump or pressurized vessel) develops pressure higher than the supply, potentially forcing contaminants into the potable water supply.
A pressure vacuum breaker (PVB) is most appropriate for which of the following applications?
Answer: Irrigation systems where the device is installed above the highest outlet
PVBs are widely used for irrigation systems and must be installed at least 12 inches above the highest downstream outlet, making elevated irrigation applications ideal.