The art of purging is slowly becoming lost, with some in the gas industry struggling to understand the importance of purging – and not knowing the correct methods and procedures to purge a gas installation. Paul Makrievski from Energy Safe Victoria offers the following advice.

Purging is defined as either being the displacement of air or an inert gas by a fuel gas (purging into service) or the displacement of a fuel gas by air or an inert gas (purging out of service).

All new gas installations need to be purged to remove any undesirable substances from the gas pipe, piping system or appliance. The reason purging is so important for a gas installation is to avoid the possibility of an explosive air and gas mixture forming in the consumer piping, appliances or confined spaces.

Small volume installations typically found in residential dwellings with a total installed pipe volume of up to 0.03m³ (30L), can be purged using the procedure as set out in AS/NZS 5601.1:2022 Appendix D.

Larger volume installations (greater than 0.03m³ or 30L+) can present some additional challenges that need to be considered.

Consider where the purge will be taking place. A purge area needs to be identified, made safe and cleared of all ignition sources. Select a suitable location where purged gases will be dispersed quickly and will not give rise to complaints about a smell of gas, taking into consideration the gas type and properties. A risk assessment should be undertaken to identify all the hazards, especially potential ignition sources, and then develop adequate control and or mitigation measures.

It is important that people onsite such as project managers and site supervisors have been told that gas purging will be taking place, and suitable fire extinguishers are situated near the venting point. Planning for the purge procedure should include isolating the purge zone with temporary fencing, or barricades and selecting the best, safest time during the day to carry out the purge, a time with minimal personnel onsite, reducing purge zone interruptions and risks involved.

Purged gas should be vented to the outside atmosphere and away from any buildings, air intakes or electrical ignition sources. A purge stack or a purge bucket may be required.

Communication is an important component to a successful and safe purge. The number of competently trained staff required to control a purging operation will vary depending on the complexity and magnitude of the purge. Onsite communications help all involved in the purging process to work in cohesion. As such, it is important to ensure all electronic communication equipment used within the immediate vicinity of the purge discharge area is intrinsically safe for use in hazardous areas. There also need to be controls in place to ensure no ignition sources are introduced once purging begins – including a strict ‘no smoking’ rule near the purge area.

There is a lot more to purging then the points raised in this article. Purging that’s done correctly will ensure safety for the gasfitter undertaking the work, and the end-user once the purge is completed. For further information and guidance to ensure a successful and safe purge, I encourage readers to head to www.energysafe.vic.gov.au and view Gas information sheet 14a (Natural Gas) or 14b (Liquified Petroleum Gas) to find out more on safe purging.