If a check valve is located at the dispenser on a suction system, how much pressure must be applied for a tightness test?

If a check valve is located at the dispenser on a suction system, how much pressure must be applied for a tightness test?

• A. It cannot be tested
• B. 150% of normal operating pressure
• C. 5 psi through the air eliminator port
• D. 10 psi through the check valve

Answer: (A)

Tightness testing needs the entire suction piping to be pressurized and held so leaks can be detected. A check valve at the dispenser only allows flow in one direction and isolates part of the suction line. When you try to pressurize from the dispenser side, the check valve prevents the test pressure from reaching the rest of the system, so you can’t establish a true, sealed test condition for the whole suction path. Because of that isolation, the test cannot be performed reliably, which is why the correct answer is that it cannot be tested. If testing is required, the valve would need to be bypassed or the section upstream/downstream tested in accordance with procedures.

Tightness testing needs the entire suction piping to be pressurized and held so leaks can be detected. A check valve at the dispenser only allows flow in one direction and isolates part of the suction line. When you try to pressurize from the dispenser side, the check valve prevents the test pressure from reaching the rest of the system, so you can’t establish a true, sealed test condition for the whole suction path. Because of that isolation, the test cannot be performed reliably, which is why the correct answer is that it cannot be tested. If testing is required, the valve would need to be bypassed or the section upstream/downstream tested in accordance with procedures.