EnergySafe Magazine Autumn 2015, issue 39 | Page 21

21 For all the latest energy safety news visit Autumn 2015 energysafe issue 39 Vent terminal exclusion zone error by Michael Weber, Technical Communicator All vent terminals must be positioned so that expelled gases can freely dissipate and not create a hazard. In the context of this article a vent terminal means the vent opening of a regulator or similar device (having a diaphragm) or the terminal of a vent line and around which there is an exclusion zone. No ignition source or opening into a building is allowed within the exclusion zone of the vent terminal. Australian and New Zealand Standard AS/NZS 5601.1:2013 clause Vent terminal location describes how the exclusion zone is defined. Recently an editorial error was identified. This error is of great concern because it vastly distorts the size of the exclusion zone around the vent’s discharge point. Currently the Standard states: AS/NZS 5601.1:2013 clause Vent terminal location: A vent terminal shall be located where gas discharge will dissipate without entering buildings or creating any hazard. The point of discharge shall— (c) n cases where there is any object i (e.g. wall, ground, etc.) in the direction of discharge and within the exclusion zone of Figure 5.3 be located so there is no ignition source or opening into a building within a sphere of radius r (of Figure 5.3) centred on the vent terminal discharge point. T= Vent terminal diameter (mm)/50, in metres. The exclusion zone shown below (shaded area) depicts a space consisting of a cylinder in the discharge direction and a hemisphere in the opposite direction of discharge from the vent terminal discharge point. The error was identified above as reading “a sphere of radius r centred on the vent terminal discharge point” instead of “a clearance of at least distance L centred on the vent terminal discharge point”. If the exclusion zone is incorrect, then there is opportunity for vented gases to enter a building through an opening or create a hazard in the immediate area; this makes the positioning of the gas discharge point crucial to ensure that gases can dissipate safely. Normally, where there is no obstruction in the direction of the discharge, determining the size of the exclusion zone is quite straight forward and the exclusion zone is in the shape of the cylinder, length L and diameter D, as depicted in Figure 5.3 (below). In cases where there is an obstruction (e.g. wall, ground, etc.) in the direction of discharge and within the exclusion zone then the point of discharge is to be positioned such that there is a clearance of at least distance L to any ignition source or opening in all directions measured from the discharge point. To remedy this situation ESV will be issuing a gas information sheet alerting gasfitters to this error and Standards Australia will publish an amendment to AS/NZS 5601. AS/NZS 5601.1:2013 Fig 5.3 and clause—Reproduced with permission from SAI Global Ltd under Licence 1503-c135. Figure 5.3: Vent terminal exclusion zone Discharge direction D r Vent terminal discharge point L Vent terminal diameter (not shown) Exclusion zone, m Not exceeding 50mm 1.5 1 0.5 New Exceeding 50mm 1.5T T 0.5T L D r New Code of Practice for gas use at public events By Michelle Robertson, Senior Media and Communications Advisor ESV has updated its long-standing Code of Practice for the safe use of LP Gas at public events in Victoria to facilitate the safe use of LP Gas at public events such as festivals, fetes, markets and sporting activities. The Code of Practice was produced in conjunction with WorkSafe Victoria, fire services CFA and MFB, Gas Energy Australia and the AGA. Prior to publication the document was also reviewed by a number of organisations involved in public events. Organisers of public events have a duty of care to provide a safe operational environment for event staff and members of the public. The Code is designed to ensure an acceptable level of gas safety to minimise gas-related incidents. Key topics include: »» gas appliance requirements including approval badges and compliance plates »» cylinders and components »» indoor, outdoor and temporary structures for housing gas appliances »» mobile catering vehicles and relocatable kitchens »» documentation and notification requirements »» responsibilities »» risks »» emergency planning »» gas cylinder storage limits »» regulations for storing and handling dangerous goods The booklet also includes an example of a Gas Safety Checklist that catering vendors and operators can use to check that key safety requirements have been met. The Code will be of use to event organisers, appliance hirers, catering vendors, gas suppliers, safety auditors and others involved in the provision and management of public events. The document is available in printed and digital form and copies may be requested by emailing ESV. lick here to request a copy of C  the document in either digital or printed form