Journeyman Plumbers Exam Backflow Prevention 5 — Questions and Answers
Question 1: A double check valve assembly (DCVA) is appropriate for which hazard classification?
- High-hazard connections only
- Low-hazard (non-health) connections only (Correct answer)
- Severe toxic hazard connections
- Any hazard level when installed with an air gap
Correct answer: Low-hazard (non-health) connections only
DCVAs are rated for low-hazard (non-health) cross-connections where contamination would be a nuisance but not a health risk, such as lawn irrigation without chemical injection.
Question 2: Under the International Plumbing Code (IPC), which backflow preventer is required for a medical dental chair water supply?
- Hose bibb vacuum breaker
- Double check valve assembly
- Reduced pressure zone assembly (Correct answer)
- Atmospheric vacuum breaker
Correct answer: Reduced pressure zone assembly
Dental chair water supplies are considered high-hazard due to potential biological contamination, requiring an RPZ assembly.
Question 3: What is the minimum distance an RPZ assembly's relief port discharge must be from a sanitary drain receptor to prevent a cross-connection?
- No minimum is required if the drain is covered
- An air gap of at least twice the drain receptor diameter
- The discharge must never connect directly to the drainage system (Correct answer)
- 1 inch above the drain rim
Correct answer: The discharge must never connect directly to the drainage system
The RPZ relief port discharge must terminate with an air gap and must never be directly piped into the drainage system to prevent a drainage cross-connection.
Question 4: Which standard published by ASSE specifically covers reduced pressure zone backflow preventers?
- ASSE 1001
- ASSE 1013 (Correct answer)
- ASSE 1020
- ASSE 1035
Correct answer: ASSE 1013
ASSE 1013 is the performance standard for reduced pressure principle backflow preventers used in potable water systems.
Question 5: A plumber connects a chemical feed pump directly to a potable water line without any backflow protection. This is best described as:
- A permitted connection if the pump has an internal check valve
- An illegal cross-connection creating a high-hazard condition (Correct answer)
- Acceptable only if the pump is downstream of a water meter
- Allowable when approved by the building owner in writing
Correct answer: An illegal cross-connection creating a high-hazard condition
Any direct connection between a chemical feed system and the potable supply without proper backflow protection is an illegal high-hazard cross-connection.
Question 6: During a backflow assembly test, the first check valve of an RPZ fails to hold. The correct action is to:
- Tighten the packing nut on the check valve stem to restore seating
- Report the failed test and have the assembly repaired or replaced before returning to service (Correct answer)
- Install a supplemental check valve on the upstream piping and retest
- Leave the assembly in place since the second check valve provides backup protection
Correct answer: Report the failed test and have the assembly repaired or replaced before returning to service
A failed backflow preventer test requires the assembly to be repaired or replaced by a qualified technician before it is returned to service.
Question 7: What is the function of the isolation (shut-off) valves that are integral to a testable backflow prevention assembly?
- They regulate downstream pressure to protect the check valves from damage
- They allow the assembly to be isolated for testing and maintenance without shutting down the entire system (Correct answer)
- They prevent thermal expansion from building pressure inside the assembly body
- They provide a secondary backflow barrier if both check valves fail
Correct answer: They allow the assembly to be isolated for testing and maintenance without shutting down the entire system
Integral isolation valves allow technicians to isolate the backflow assembly for annual testing and repairs while minimizing disruption to the rest of the system.
Journeyman Plumbers Exam Backflow Prevention 5
A double check valve assembly (DCVA) is appropriate for which hazard classification?