CSLB C-36 Plumbing ContractorFixture and Appliance InstallationHard
A plumber is installing a backflow prevention assembly on a residential irrigation system connected to the potable water supply. Which type of backflow prevention assembly is typically required by code for this application in California, considering potential health hazards?
- AAtmospheric Vacuum Breaker (AVB)
- BReduced Pressure Principle Assembly (RP)
- CDouble Check Valve Assembly (DCVA)
- DPressure Vacuum Breaker (PVB)
Show answer & explanationAnswer & explanation
Correct answer: B. Reduced Pressure Principle Assembly (RP)
For irrigation systems connected to potable water, especially those with potential for chemical injection or cross-connection with non-potable water, a Reduced Pressure Principle (RP) assembly is typically required in California due to its ability to protect against both backpressure and backsiphonage and its high hazard protection.
Why the other options are wrong
- A. AVBs are for low-hazard, continuous pressure applications and cannot be subjected to continuous line pressure or backpressure.
- C. DCVAs are suitable for low hazard applications, but irrigation systems can be high hazard.
- D. PVBs only protect against backsiphonage and cannot protect against backpressure, which can occur in irrigation systems.
Reduced Pressure Principle (RP) Assembly
A backflow prevention device consisting of two independently operating check valves, an automatically operating differential relief valve located between the check valves, and two shutoff valves.
- Protects against both backpressure and backsiphonage.
- Suitable for high-hazard applications.
- Requires annual testing by a certified backflow tester.
Memory trick: RP always provides the 'Really Protective' solution for high hazards.