What is the required test pressure for an interim air test?

• A. 100 psi
• B. 75 psi
• C. 50 psi
• D. 25 psi

Answer: (C)

The interim air test is a temporary check of the installed standpipe piping by pressurizing it with air to reveal leaks before the final tests. The required test pressure is 50 psi because it’s high enough to expose leaks around joints, fittings, and components, yet low enough to avoid stressing or damaging equipment and gaskets that aren’t rated for higher pressures. Pressures much higher could mask or cause leaks, or harm valves and fittings, while a pressure much lower wouldn’t reliably reveal leaks. So 50 psi strikes the right balance for an interim air verification.