Test procedures

A test procedure is three things: the sequence of steps, the number that means stop, and the judgment call when a result lands near the line. Each page in this section covers one test that way. Method first, then pass criteria with the actual numbers, then what a failure or a marginal result says about the system.

The number lives in the edition, not the truck

Pass criteria belong to a specific edition of a specific standard. Take the main drain test. NFPA 25, 2023 edition, section 13.2.5 says a full-flow pressure drop of more than 10 percent against previous test results means you investigate the supply. The baseline is the recorded prior result, not what the last technician remembers the gauge doing. That is why every number on these pages carries the standard, the edition, and the section beside it. A criterion without its edition is folklore, and folklore does not survive an audit or an AHJ.

Running a test versus interpreting one

Anyone with the right wrench can run a main drain. Interpreting it means knowing the baseline, the trend, and whether the standard treats the finding as a deficiency or an impairment. A marginal result is information, not a rounding problem: retest under the same conditions, compare against the last recorded value, and write down both numbers. Averaging a bad reading into a good one is how a slowly closing valve stays hidden for five years.

Terms these pages lean on, deficiency, impairment, residual pressure, are defined in the glossary. If your question is when a test is due rather than how it runs, start with the ITM overview.