Backflow Prevention & Cross-Connection Control Flashcards
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Read the first 7 Backflow Prevention & Cross-Connection Control flashcards as text
Which scenario best represents a high-hazard cross-connection requiring an RPZ assembly?
Answer: A direct connection between potable water and a chemical mixing or processing tank
A connection between potable water and a chemical processing tank is a high-hazard cross-connection because contamination could cause serious illness or death, requiring the maximum protection of an RPZ.
What action is required when an RPZ assembly's relief valve discharges water continuously during normal operation?
Answer: Remove the assembly from service and have it repaired or replaced by a certified tester
Continuous discharge from an RPZ relief valve indicates that one or both check valves have failed, and the assembly must be taken out of service immediately until repaired by a certified tester.
At what minimum height above the highest downstream outlet must a pressure vacuum breaker (PVB) be installed?
Answer: 12 inches above the highest outlet
PVBs must be installed at least 12 inches above the highest downstream outlet to protect against both backsiphonage and backpressure conditions.
Why is thermal expansion a critical concern in a closed plumbing system that has a backflow preventer installed?
Answer: Heated water cannot expand back toward the meter, creating dangerous pressure increases that can damage water heaters and pipes
A backflow preventer creates a closed system; when a water heater heats the water, it expands but cannot push back toward the meter, causing pressure buildup that can damage the water heater and plumbing components.
Which assembly or device would typically be required for a residential lawn irrigation system with a fertilizer injection system connected to the public water supply?
Answer: A reduced pressure zone (RPZ) assembly due to the chemical injection hazard
Fertilizer injection elevates the irrigation system to a high-hazard cross-connection because chemicals entering the potable supply pose a health risk, requiring an RPZ assembly.
What is the precise definition of 'backflow' as used in plumbing and cross-connection control?
Answer: The undesirable reversal of water flow direction in a potable water distribution system
Backflow is specifically defined as the undesirable reversal of flow in a potable water distribution system that can allow contaminants to enter the clean water supply through backsiphonage or backpressure.
Which installation requirement applies universally to ALL types of testable backflow prevention assemblies under U.S. plumbing codes?
Answer: They must be readily accessible for inspection, testing, and maintenance
All testable backflow prevention assemblies must be installed in accessible locations so that certified testers can perform the required periodic inspections, testing, and any necessary maintenance or repair.