IA Backflow Prevention & Cross-Connection Control 2 — Questions and Answers
Question 1: Which backflow prevention assembly provides the highest level of protection against both back-pressure and back-siphonage?
- Atmospheric Vacuum Breaker (AVB)
- Pressure Vacuum Breaker (PVB)
- Reduced Pressure Zone (RPZ) assembly (Correct answer)
- Double Check Valve (DCV) assembly
Correct 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.
Question 2: An Atmospheric Vacuum Breaker (AVB) must be installed at what position relative to the highest downstream outlet?
- At least 6 inches below the highest downstream outlet
- At least 6 inches above the highest downstream outlet (Correct answer)
- At the point of connection to the water meter regardless of outlet elevation
- Underground in a valve box at the same elevation as the lateral lines
Correct 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.
Question 3: How does a Pressure Vacuum Breaker (PVB) differ from an Atmospheric Vacuum Breaker (AVB)?
- A PVB cannot be placed under continuous supply pressure
- A PVB can remain under continuous pressure due to its internally loaded check valve and poppet (Correct answer)
- A PVB is only approved for low-hazard applications, while an AVB handles high hazards
- A PVB does not require annual field testing unlike the AVB
Correct 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.
Question 4: A Double Check Valve (DCV) assembly is most appropriate for which type of application?
- High-hazard applications such as chemical or fertilizer injection systems
- Low-to-moderate hazard applications where the potential contaminant is not a health threat (Correct answer)
- Situations where there is absolutely no risk of back-pressure from the downstream system
- Locations where maintaining a physical air gap is not structurally possible
Correct 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.
Question 5: Which backflow prevention device is NOT testable in the field using standard test equipment?
- Reduced Pressure Zone (RPZ) assembly
- Double Check Valve (DCV) assembly
- Atmospheric Vacuum Breaker (AVB) (Correct answer)
- Pressure Vacuum Breaker (PVB)
Correct 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.
Question 6: Under which conditions is it acceptable to install a Pressure Vacuum Breaker (PVB) for residential or commercial irrigation?
- When the irrigation system uses chemical injection or fertilizer proportioning
- When no chemical injection is used and the PVB is installed above all downstream outlets (Correct answer)
- When the system is supplied by reclaimed or recycled water
- When the local water authority has specifically required an RPZ on the permit
Correct 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.
Question 7: How many independently operating check valves are contained in a Reduced Pressure Zone (RPZ) assembly?
- One check valve and one pressure regulator
- Two check valves plus a differential pressure relief valve (Correct answer)
- Three check valves in series
- Two check valves with no additional relief valve
Correct 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.
IA Backflow Prevention & Cross-Connection Control 2
Which backflow prevention assembly provides the highest level of protection against both back-pressure and back-siphonage?