Journeyman Plumber ExamDrainage, Waste, and Venting (DWV) SystemsMedium
A plumber is performing a final inspection of a DWV system in a new residential construction. What is the maximum allowable pressure drop during a 15-minute air test?
- A2.0 psi
- B1.0 psi
- C0.5 psi
- D3.0 psi
Show answer & explanationAnswer & explanation
Correct answer: C. 0.5 psi
During an air test for a DWV system, the pressure gauge must indicate a minimum test pressure of 5 psi, and this pressure must remain constant for at least 15 minutes. A drop of 0.5 psi or more would indicate a leak, thus the maximum allowable drop is less than 0.5 psi (or essentially none).
Why the other options are wrong
- A. A 2.0 psi drop is a definite failure, indicating a significant leak.
- B. A 1.0 psi drop is a definite failure, indicating a significant leak.
- D. A 3.0 psi drop is a definite failure, indicating a significant leak.
DWV Air Test Pressure Drop
An air test for a DWV system involves pressurizing the entire system with air and monitoring for pressure drops to detect leaks. Any significant pressure drop indicates a leak that must be located and repaired.
- Minimum 5 psi test pressure.
- Held for 15 minutes.
- No perceptible pressure drop allowed.
- Detects leaks in joints/fittings.
Memory trick: Air Test Pressure Must Hold Tight, No Drop Allowed, Day or Night.