BAT Installation Techniques 3 — Questions and Answers
Question 1: When installing a pressure vacuum breaker (PVB) for an irrigation system, the assembly must be installed at least how far above the highest downstream sprinkler head?
- 3 inches
- 6 inches (Correct answer)
- 12 inches
- 24 inches
Correct answer: 6 inches
PVBs must be installed a minimum of 6 inches above the highest downstream outlet to ensure the air inlet opens under back-siphonage conditions.
Question 2: Which condition makes installation of a PVB (pressure vacuum breaker) inappropriate for an irrigation system?
- The system uses drip emitters instead of spray heads
- The system has zones that operate simultaneously
- The downstream piping can be subjected to backpressure (Correct answer)
- The water supply pressure exceeds 80 psi
Correct answer: The downstream piping can be subjected to backpressure
PVBs are not designed to withstand backpressure; only back-siphonage protection is provided, so any system capable of creating downstream pressure requires an RP assembly.
Question 3: A spill-resistant pressure vacuum breaker (SVB) differs from a standard PVB primarily in that it:
- Can be installed below the highest downstream outlet
- Uses a poppet check instead of an internal air inlet
- Does not discharge water from the air inlet during normal pressure fluctuations (Correct answer)
- Is approved for high-hazard cross-connections
Correct answer: Does not discharge water from the air inlet during normal pressure fluctuations
The SVB contains a sealed check that prevents nuisance water spillage from the air inlet during normal pressure cycles while still opening under true vacuum conditions.
Question 4: When making a threaded connection to a backflow preventer body, the installer should apply thread sealant:
- To both male and female threads for maximum seal
- To the male threads only, keeping it away from the first two threads (Correct answer)
- To the female threads only to avoid contaminating the waterway
- Thread sealant is prohibited; only mechanical gaskets may be used
Correct answer: To the male threads only, keeping it away from the first two threads
Sealant is applied to male threads only and kept back from the first thread to prevent sealant from entering the waterway and potentially damaging internal components.
Question 5: An installer is connecting copper tubing to a bronze-bodied backflow preventer using a dielectric union. The purpose of this fitting is to:
- Provide a union joint for assembly removal without cutting pipe
- Prevent galvanic corrosion between dissimilar metals (Correct answer)
- Reduce water velocity through the assembly inlet
- Allow the assembly to rotate for test cock access
Correct answer: Prevent galvanic corrosion between dissimilar metals
Dielectric unions isolate dissimilar metals electrically to prevent galvanic corrosion that occurs when two different metals are in direct contact in the presence of water.
Question 6: The flow direction arrow cast or stamped on a backflow preventer body must align with:
- The direction water flows toward the supply (upstream)
- The direction water flows toward the hazard (downstream) (Correct answer)
- The orientation of the test cocks for easiest access
- The direction of gravity to ensure proper drainage
Correct answer: The direction water flows toward the hazard (downstream)
The flow arrow indicates the direction water travels through the assembly from supply to hazard, and incorrect installation reverses the check valves, eliminating all protection.
Question 7: What is the purpose of installing a strainer upstream of a backflow prevention assembly on a recycled water system?
- To increase water pressure to the assembly inlet
- To remove particulates that could prevent check valves from seating properly (Correct answer)
- To reduce the assembly's internal pressure differential
- To prevent backpressure from the recycled water system
Correct answer: To remove particulates that could prevent check valves from seating properly
Strainers catch debris before it enters the assembly, preventing particles from lodging under check discs and causing them to remain open.
BAT Installation Techniques 3
When installing a pressure vacuum breaker (PVB) for an irrigation system, the assembly must be installed at least how far above the highest downstream sprinkler head?