Backflow prevention device types and the cross-connection scenarios that require them, tested on plumbing licensing exams.
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- What is a Reduced Pressure Zone (RPZ) device?
- A backflow prevention device with two check valves and a relief valve that maintains a pressure zone between them to prevent backflow in both directions.
- What type of hazard requires an RPZ device instead of a Double Check Valve?
- High hazard (health threat), such as chemical injection or contaminated water connections.
- Define a cross-connection in plumbing.
- A physical link allowing potable water to come into contact with non-potable or contaminated water.
- What is backflow?
- Reverse flow of non-potable water, contaminants, or wastewater into the potable water supply.
- How does siphonage backflow occur?
- When pressure in the potable water line drops below pressure in the cross-connected line, causing reverse flow.
- How does pressure backflow occur?
- When pressure from a cross-connected system exceeds the pressure in the potable water supply, forcing water backward.
- What is a Double Check Valve Assembly used for?
- Prevention of backflow in low-hazard cross-connections where the contaminant poses no health risk.
- Where is an Atmospheric Vacuum Breaker typically installed?
- On outdoor hose bibbs and indoor faucets to prevent siphonage of non-potable water.
- At what minimum height must an Atmospheric Vacuum Breaker be installed above the outlet?
- At least 6 inches above the flood level rim or highest opening of the outlet.
- What is a Pressure Vacuum Breaker commonly used for?
- Protection against backflow on lawn irrigation systems, heating systems, and low-hazard applications.
- How does an Atmospheric Vacuum Breaker prevent backflow?
- By allowing air to enter the line when pressure drops, which breaks the siphon and prevents reverse flow.
- How often must an RPZ device be tested and certified?
- Annually, by a certified backflow device tester.
- How often must a Double Check Valve Assembly be tested?
- Every five years by a certified backflow device tester.
- What backflow device is required for a lawn irrigation system with chemical injection?
- A Reduced Pressure Zone device, due to the high hazard of pesticide and fertilizer contamination.
- What backflow device is required where a boiler system has its own water supply line?
- A Reduced Pressure Zone device or Double Check Valve, depending on whether additives or high-temperature water poses a health hazard.
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