Gas safety: purging a gas cylinder

With the current electricity situation and cost, many of us are using gas more and more in our homes. Here’s a pertinent safety tip.

If you use LPG (Liquefied Petroleum Gas) in your kitchen or elsewhere in your home for a heater or for a geyser, it’s important to follow correct procedures when purchasing and connecting your gas cylinder. Failure to do so could be dangerous and costly. In this blog, we’ll look at one such procedure: purging gas on a cylinder.

When cylinders are manufactured, they are filled with an inert, non-flammable gas, usually nitrogen. Purchased cylinders, on the other hand, are sold off the shelf empty. Once a cylinder has been filled with LPG, it needs to be purged to expel any remaining nitrogen into the atmosphere. Mixing an inert gas and LPG gas may result in an improper burn at the burner and could even prevent the gas from igniting. The second reason that purging is important, especially on exchange-type cylinders, is to remove any dust or dirt that may be in the nozzle – you don’t want that dust to block your burners.

Purging is easy, but it needs to be done in a safe environment. LPG is obviously a highly flammable substance, so don’t purge gas indoors or within the vicinity of any source of ignition. Place the cylinder with the outlet facing away from you and open the valve, giving it a five-second blast. It is recommended to do two purges. After purging, take care to inspect the bullnose rubber seal.

If this is damaged or torn, you need to replace it. These valves are reverse-threaded for safety reasons and the regulator should only ever be hand tightened – don’t use pliers or any other tool. Once it is tightened, turn on the gas, listen and smell for leaks, then do a leak test. A mix of dishwashing liquid and water works well – pour this over the connection and look for air bubbles, which indicate a leak.

When purchasing a gas cylinder, be sure to check the size of the nozzle. Gas heaters and stoves usually take the five-eighth-inch thread, whereas smaller gas appliances take a half-inch thread. Gas cylinders are marked with the empty weight, so a 9 kg ALVA cylinder for example, will weigh 9 kg when empty and about 19 kg when full. Legally, a 9 kg cylinder can be stored indoors – anything larger needs to be kept outdoors with additional safety considerations. Your gas installer will be able to advise you on these.

Gas is a cost-efficient source of energy, but you do need to handle gas with safety in mind. Don’t drop or damage the cylinder, don’t modify the cylinder in any way, ensure gas appliances are correctly installed and use the gas only for its intended purpose. Follow these tips and you will get many years of safe usage from your cylinder. Remember that Builders has a wide range of gas appliances, cylinders and all the hardware you could need.