Backflow Prevention & Cross-Connection Control Flashcards

Which backflow prevention assembly provides the highest level of protection against both back-pressure and back-siphonage?

Answer: Reduced Pressure Zone (RPZ) assembly

The RPZ assembly provides the highest mechanical protection because it maintains a zone of reduced pressure between two check valves and vents any backflow to the atmosphere via a relief valve.

An Atmospheric Vacuum Breaker (AVB) must be installed at what position relative to the highest downstream outlet?

Answer: At least 6 inches above the highest downstream outlet

AVBs must be installed at least 6 inches above the highest downstream outlet to prevent submersion and ensure the device can open to atmosphere and protect against siphonage.

How does a Pressure Vacuum Breaker (PVB) differ from an Atmospheric Vacuum Breaker (AVB)?

Answer: A PVB can remain under continuous pressure due to its internally loaded check valve and poppet

A PVB has an internally loaded check valve and poppet assembly that allows it to remain under continuous supply pressure, whereas an AVB must not be subjected to continuous pressure.

A Double Check Valve (DCV) assembly is most appropriate for which type of application?

Answer: Low-to-moderate hazard applications where the potential contaminant is not a health threat

DCVs are suitable for low-to-moderate hazard cross-connections where the potential contaminant would not pose a direct health hazard, such as non-toxic aesthetic contaminants.

Which backflow prevention device is NOT testable in the field using standard test equipment?

Answer: Atmospheric Vacuum Breaker (AVB)

Atmospheric Vacuum Breakers lack test cocks and cannot be field-tested; they must be replaced if suspected of failure, unlike RPZ, DCV, and PVB assemblies which have test ports.

Under which conditions is it acceptable to install a Pressure Vacuum Breaker (PVB) for residential or commercial irrigation?

Answer: When no chemical injection is used and the PVB is installed above all downstream outlets

PVBs are acceptable for irrigation systems without chemical injection, provided they are installed above all downstream outlets as required by code.

How many independently operating check valves are contained in a Reduced Pressure Zone (RPZ) assembly?

Answer: Two check valves plus a differential pressure relief valve

An RPZ contains two independently operating spring-loaded check valves and a differential pressure relief valve that opens to atmosphere if the pressure zone between the checks is compromised.