4.2 Pneumatic (Air) Testing, Vacuum Testing & Leak Detection

Pneumatic air testing

Air testing can be efficient, but compressed gas stores much more releasable energy than water. A detached plug or cap can become a projectile. Use air only where the compliance documents permit it, use rated equipment, positively restrain plugs, and keep everyone out of the line of fire.

E1/VM1 low-pressure method

For the low-pressure procedure, introduce air until the pressure is 300 mm water gauge. Allow the air temperature to become uniform, disconnect the air supply, and after five minutes measure the pressure. The drop must not exceed 50 mm water gauge. The numbers belong together; replacing 300 mm water gauge with 15 kPa would be a major error because 300 mm water gauge is about 2.9 kPa.

Use a suitable water manometer or calibrated gauge with adequate resolution. Check hoses and temporary fittings before blaming buried pipework. Temperature changes can change pressure even when no air escapes, which is why stabilization and disconnection are part of the sequence.

E1/VM1 high-pressure method

For the high-pressure procedure, raise pressure to 25 kPa and allow at least two minutes for stabilization. Disconnect the supply. Let pressure fall to 17 kPa, then measure the time to fall to 14 kPa. The minimum times are 3 minutes for 90 mm and 100 mm pipe, 4 minutes for 150 mm pipe, and 6 minutes for 225 mm pipe.

Do not invent a “zero pressure drop” criterion. The high-pressure method intentionally measures a controlled decay between two pressures. Do not continue adding air during the timed interval.

Safety controls

Identify plug diameter, rated pressure, restraint load, access, and escape path in the test plan. Restraint is structural; leaning a board against a plug or relying on an inflatable seal is not enough. Establish barriers and prohibit anyone from standing in front of a plug, cap, branch, or temporary connection. Fit pressure-limiting equipment suitable for the method and release pressure remotely where practical.

Inspect the system before charging. Unsupported fittings, solvent joints that have not achieved manufacturer cure time, and damaged inspection caps should not be exposed to pressure. Increase pressure gradually. Stop if the restraint moves, a fitting distorts, or an abnormal sound occurs.

Diagnosis and retest

A compatible leak-detection solution can identify exposed leakage, but clean and inspect the joint afterward. Sectional testing can narrow the search. Smoke may help trace an odour path or cross-connection, but it is a different diagnostic procedure and not automatically an acceptance test.

After a failure, fully depressurise, verify zero pressure, repair the defect, and repeat the complete specified sequence. Never loosen a plug that may still be loaded. Record test boundaries, method, pipe sizes, initial pressures, stabilization times, timed results, gauge identification, ambient conditions, repairs, and final acceptance.

Method-selection check

If the consent cites AS/NZS 3500.2 through G13/AS3, follow that edition’s procedure rather than substituting E1/VM1 values. If G13/AS2 expressly accepts an E1/VM1 air test, use the E1/VM1 sequence above. The reviewer should be able to trace every number in the test sheet to one named method. A safe test with a mismatched acceptance criterion is not a verified compliance result.

Independent source-check exercise

For 4.2 Pneumatic (Air) Testing, Vacuum Testing & Leak Detection, practise answering from evidence rather than recall. Write the controlling source, its edition or effective date, its scope, and the exact paragraph, table, figure, or manufacturer instruction that supports the decision. Then state the site inputs that can change the result. In this section those inputs include The E1/VM1 low-pressure method charges to 300 mm water gauge, stabilises for five minutes, and permits no more than 50 mm drop.; The high-pressure method charges to 25 kPa, stabilises for at least two minutes, and times the decay from 17 kPa to 14 kPa.; Minimum high-pressure decay times are 3 minutes for 90–100 mm, 4 minutes for 150 mm, and 6 minutes for 225 mm pipe..

Build a four-column check: proposed condition, source requirement, evidence observed, and action. Test the answer with one changed assumption. A different pipe size, discharge-unit load, ground condition, licence status, authority, compliance path, or consent condition may produce a different result. If it does, explain why; if it does not, show which requirement remains controlling.

Finish with a field-verification plan. Name what must be inspected before concealment, what instrument or record demonstrates it, who has authority to accept a change, and what appears on the as-built or completion file. This exercise turns an open-book fact into certifying-level judgement. It also exposes accidental mixing of standards: if the source for a dimension differs from the source for the test or approval, either return to one complete compliance path or document the proposal as an Alternative Solution. Do not promote an example value into a national rule.