CSLB C-36 Plumbing ContractorRough-in PlumbingHard
A plumbing contractor is installing a backflow prevention device on a potable water supply line to an irrigation system. Which type of backflow preventer is typically required for this high-hazard application where there is a constant pressure condition and potential for back-siphonage and backpressure?
- AAtmospheric Vacuum Breaker (AVB)
- BDouble Check Valve Assembly (DCVA)
- CReduced Pressure Principle Backflow Assembly (RPBA)
- DPressure Vacuum Breaker (PVB)
Show answer & explanationAnswer & explanation
Correct answer: C. Reduced Pressure Principle Backflow Assembly (RPBA)
For high-hazard applications like irrigation systems with constant pressure, the Reduced Pressure Principle Backflow Assembly (RPBA) is typically required. It provides the highest level of protection against both back-siphonage and backpressure by incorporating a relief valve that opens to atmosphere when pressure differentials are compromised.
Why the other options are wrong
- A. An AVB protects against back-siphonage only and requires a non-continuous pressure supply, making it unsuitable for irrigation systems.
- B. A DCVA is suitable for medium-hazard applications but does not provide sufficient protection for high-hazard situations with potential backpressure.
- D. A PVB protects against back-siphonage only and is not effective against backpressure, making it unsuitable for constant pressure systems.
Backflow Preventer Types
Devices designed to prevent the reverse flow of contaminated water into a potable water supply system, categorized by their protection level.
- Protects public health by preventing contamination.
- Selection depends on hazard level (low, medium, high).
- Tested and certified annually.
Memory trick: Hazard High? RPBA is the 'Right Protection' to Apply.