During an air test, the pipe must be pressurized to what range above atmospheric pressure?

• A. 1 to 2 psi
• B. 2 to 4 psi
• C. 3 to 5 psi
• D. 5 to 7 psi

Answer: (C)

Air testing relies on applying a small positive pressure above atmospheric so leaks show up as a pressure drop. The range of 3 to 5 psi is chosen because it provides enough pressure to reveal leaks in joints and fittings without stressing the pipe system too much. Pressurizing only 1 to 2 psi isn’t reliably detectable for leaks, while pushing 5 to 7 psi can risk damaging pipes or fittings and creates unnecessary safety concerns. So, 3 to 5 psi balances leak detectability with safety and structural limits, making it the best answer.