BAT Installation Techniques 2 — Questions and Answers
Question 1: What is the minimum clearance required below a reduced pressure principle (RP) backflow preventer installed in a pit or vault?
- 6 inches
- 12 inches (Correct answer)
- 18 inches
- 24 inches
Correct answer: 12 inches
A minimum of 12 inches of clearance is required below an RP assembly to allow the relief valve to discharge freely and for maintenance access.
Question 2: When installing a double check valve assembly (DCVA) in a vault, the assembly must be positioned so that:
- The flow arrow points downstream toward the hazard
- The test cocks are accessible without entering a confined space (Correct answer)
- The shutoff valves are located outside the vault
- The assembly is submerged for freeze protection
Correct answer: The test cocks are accessible without entering a confined space
Test cocks must remain accessible for annual testing, and vaults meeting confined space criteria require special entry procedures, so positioning for accessible testing is critical.
Question 3: Which pipe support requirement applies specifically to large-diameter RP assemblies (3 inches and larger) during installation?
- Supports are not required if the assembly is threaded
- Supports must be placed only on the downstream shutoff valve
- The assembly body must be independently supported to prevent stress on connecting piping (Correct answer)
- Hanger rods must be attached directly to the relief valve body
Correct answer: The assembly body must be independently supported to prevent stress on connecting piping
Large assemblies must be independently supported because their weight would otherwise stress the connecting pipe joints and fittings.
Question 4: A backflow preventer is being installed on a fire sprinkler system service line. Which additional requirement typically applies?
- An RP assembly must always be used regardless of hazard level
- The assembly must include a supervised OS&Y shutoff valve (Correct answer)
- Test cocks must be plugged to prevent unauthorized testing
- The assembly must be installed in a heated enclosure only
Correct answer: The assembly must include a supervised OS&Y shutoff valve
Fire protection systems typically require supervised (monitored) OS&Y gate valves so that any unauthorized shutoff triggers an alarm.
Question 5: When installing an RP assembly above ground in an area subject to freezing temperatures, the BEST practice is to:
- Wrap the assembly in pipe insulation only
- Install a heated enclosure with adequate relief valve drainage (Correct answer)
- Substitute a double check assembly since it has no external relief port
- Bury the assembly below the frost line
Correct answer: Install a heated enclosure with adequate relief valve drainage
A heated enclosure protects the assembly from freezing while ensuring the relief valve drain path remains clear and functional.
Question 6: The relief valve outlet of an RP backflow preventer installed indoors must discharge:
- Directly into the building drain system via a P-trap
- To an air gap over an approved drainage receptor (Correct answer)
- Into the cold water supply line as a recirculation measure
- Through a check valve to prevent sewer gases from entering
Correct answer: To an air gap over an approved drainage receptor
The relief valve must discharge to an air gap above a drain receptor to prevent siphoning of contaminated water back into the assembly.
Question 7: During installation, a technician notices the upstream shutoff valve supplied with an RP assembly is a ball valve rather than a gate valve. This is:
- Unacceptable; only gate valves are approved for RP assemblies
- Acceptable if the ball valve provides full-port flow (Correct answer)
- Unacceptable; only globe valves provide the required flow restriction
- Acceptable only if the downstream valve is a gate valve
Correct answer: Acceptable if the ball valve provides full-port flow
Full-port ball valves are listed and approved as integral shutoffs on many RP assemblies and provide the required full-flow opening.
BAT Installation Techniques 2
What is the minimum clearance required below a reduced pressure principle (RP) backflow preventer installed in a pit or vault?