25.2.2 Dry Pipe and Double Interlock Preaction System(s) Air Test

In addition to the standard hydrostatic test, an air pressure leakage test at 40 psi (2.7 bar) shall be conducted for 24 hours. Any leakage that results in a loss of pressure in excess of 1¹/₂ psi (0.1 bar) for the 24 hours shall be corrected.

Modifications to existing systems shall be tested for air leakage using one of the following test methods:

1. An air pressure test at 40 psi (2.7 bar) shall be performed for 2 hours.
   1. The system shall be permitted to lose up to 3 psi (0.2 bar) during the duration of the test.
   2. Air leaks shall be addressed if the system loses more than 3 psi (0.2 bar) during this test.
2. With the system at normal system air pressure, the air source shall be shut off for 4 hours. If the low pressure alarm goes off within this period, the leaks shall be addressed.

Where systems are installed in spaces that are capable of being operated at temperatures below 32°F (0°C), air or nitrogen gas pressure leakage tests required in 25.2.2 shall be conducted at the lowest nominal temperature of the space.