Gas-Water Leak Detection Safe Work Method Statement

Before entering pool equipment pits, pump rooms, or valve chambers, conduct atmospheric testing using calibrated multi-gas detector measuring four critical parameters: oxygen content (must be 19.5-23.5%, normal air is 20.9%), flammable gas concentration (must be below 5% of Lower Explosive Limit to prevent explosion risk), hydrogen sulfide (must be below 10 ppm, toxic above this level), and carbon monoxide (must be below 30 ppm for short-term exposure). Testing must sample atmosphere at multiple depths as heavier-than-air gases including LPG, carbon dioxide, and hydrogen sulfide accumulate at pit bottom even when upper levels test safe. The gas detector must be calibrated within previous 30 days with calibration certificates available for regulatory inspection. Bump-test the detector before each use by exposing to known gas concentrations verifying correct response. If any parameter is outside safe range, implement forced ventilation using blowers and re-test until safe levels are achieved before entry. Maintain continuous atmospheric monitoring during entry as conditions can deteriorate rapidly. If alarms sound during work, evacuate immediately and investigate cause before re-entering.

Compressed air can be used for pressure testing pool plumbing but creates greater hazards than water testing due to stored energy in compressed gas. If pipes or fittings fail during air testing, explosive decompression releases energy rapidly creating projectile hazards from flying components, loud noise potentially causing hearing damage, and greater injury potential if workers are nearby. Water testing is preferred where possible as water is incompressible and releases stored energy more gradually if failures occur. If compressed air testing is necessary (such as when testing pipes that will be buried and need to be dry), implement strict safety controls including limiting test pressure to minimum required (typically 100-150 kPa), using calibrated pressure gauges and pressure relief valves, establishing exclusion zones with workers positioned behind barriers during testing, increasing pressure gradually in small increments watching for leaks, and depressurizing system completely before approaching to investigate any issues. Australian Standard AS/NZS 3500.4 covers testing of plumbing installations and provides guidance on test pressures and methods. For pool plumbing, water testing is generally more practical and safer. Reserve air testing for specific situations where water testing is unsuitable, and implement enhanced safety controls for air test procedures.

Yes, all gas leak detection, testing, and repair work on pool heater gas systems must be performed by licensed gasfitters holding current licenses under state/territory gas licensing regulations. This includes testing gas supply lines for leaks, soap testing connections, using electronic leak detection equipment on gas systems, adjusting or repairing gas regulators and valves, and certifying gas installations safe for operation. Australian Standard AS/NZS 5601 governs gas installations and requires licensed gasfitters for any work on gas supply systems. Pool technicians without gas licenses can isolate gas supply at meter or cylinder connection as an emergency measure but must engage licensed gasfitter for all testing, diagnostic work, and repairs. Gas leaks create serious explosion and asphyxiation hazards requiring specialized knowledge and equipment. Licensed gasfitters have training in gas properties, explosion risks, proper testing methods, and regulatory requirements. They carry insurance for gas work and understand consequences of errors. Using unlicensed workers for gas leak detection creates enormous liability if explosions or injuries occur, with potential criminal prosecution for illegal gas work. Gas connection insurance typically excludes coverage for work by unlicensed persons. The cost of engaging licensed gasfitter is minor compared to explosion risks and potential legal consequences of unlicensed gas work.

If gas detection alarms sound during confined space entry, immediately evacuate the confined space without attempting to identify the alarm source or investigate conditions. Move to fresh air location upwind from the confined space. Account for all workers who were in or near the confined space ensuring everyone has evacuated. Do not re-enter the space or allow others to enter until the cause is identified and corrected. Notify supervisor or site management about the alarm event. Implement additional forced ventilation using blowers to supply fresh air and exhaust contaminated atmosphere. After adequate ventilation period (minimum 20-30 minutes), conduct atmospheric testing from outside the space using detector on extended probe without worker entry. Only re-enter when testing confirms all atmospheric parameters are within safe ranges—oxygen 19.5-23.5%, flammable gas below 5% LEL, hydrogen sulfide below 10 ppm, carbon monoxide below 30 ppm. Investigate and correct the source of the contamination before resuming work. If gas leak or oxygen deficiency is detected, engage specialists such as gasfitters or confined space rescue services to investigate and correct problems. Document the alarm event including what triggered alarm, how long workers were exposed, corrective actions taken, and re-test results. Workers who were exposed to hazardous atmospheres should be medically assessed even if they report feeling fine, as some toxic gas effects develop over hours. Common errors include workers ignoring alarms thinking they are false alarms or equipment faults, continuing to work hoping the alarm will stop, or entering contaminated spaces to identify the source—these responses have caused multiple fatalities when atmospheres were actually hazardous.

The ventilation duration required before confined space entry depends on space volume, contamination level, and ventilation airflow rate. A common requirement is to achieve 7-10 complete air changes before entry, meaning the volume of fresh air supplied equals 7-10 times the confined space volume. For example, a pump room with 20 cubic metre volume and ventilation fan supplying 100 cubic metres per hour would require (20m³ × 7 changes) ÷ 100 m³/h = 1.4 hours of ventilation before entry. However, this calculation assumes perfect mixing which rarely occurs—dead zones, stratification, and heavier-than-air gases may persist despite ventilation. Therefore, atmospheric testing is mandatory regardless of ventilation duration, and cannot be replaced by assumed adequate ventilation time. Best practice procedure is: (1) provide forced ventilation for minimum 20-30 minutes before initial atmospheric testing, (2) conduct atmospheric testing from outside the space using detector on extension probe, (3) continue ventilation and conduct repeated testing if unsafe levels are detected, (4) only proceed with entry when testing confirms safe atmosphere, (5) maintain continuous ventilation throughout the entry period, and (6) conduct repeat atmospheric monitoring every 2 hours during extended entries. Atmospheric conditions can deteriorate during work from gas leaks, oxygen consumption, or chemical off-gassing, making continuous ventilation and periodic re-testing essential. Document ventilation duration and test results on confined space entry permits.