When is the initial pressure test conducted by the installer?

When is the initial pressure test conducted by the installer?

• A. after blowdown of the distribution piping
• B. before installation of station rough-in assemblies
• C. after installation of the alarm sensors
• D. before blowdown of the distribution piping

Answer: (A)

The initial pressure test is done after the distribution piping has been purged of air and moisture by a blowdown. Purging ensures the test reads actual leaks in the metal piping rather than air pockets, giving an accurate indication of the system’s integrity at the test pressure. By testing after blowdown, you verify the piping network itself before adding components like rough-in assemblies or alarm sensors, which could affect readings or introduce additional leakage paths. Testing before blowdown would mask leaks with trapped air, and testing after installing sensors or before completing the purge would not reflect the true condition of the piping.

The initial pressure test is done after the distribution piping has been purged of air and moisture by a blowdown. Purging ensures the test reads actual leaks in the metal piping rather than air pockets, giving an accurate indication of the system’s integrity at the test pressure. By testing after blowdown, you verify the piping network itself before adding components like rough-in assemblies or alarm sensors, which could affect readings or introduce additional leakage paths. Testing before blowdown would mask leaks with trapped air, and testing after installing sensors or before completing the purge would not reflect the true condition of the piping.