Industrial gas cylinders are used for several different purposes, and they hold various types of gases. Oxygen cylinders are used for medical purposes, for example, while propane is used to heat up grills. An expiration date for a gas cylinder is important as the cylinder is not guaranteed to hold potency after that date. Manufacturers vary in their methods of reflecting expiration dates. Make sure to find out where your expiration date is located.
Look for the date of expiration on the top of the cylinder. More often then not, this is where you will find it. If not, check the side of the cylinder. It will either be a numerical expiration date, such as 9/2009, or in written form, as in September 2009.
Look for the words "Expiration Date," to confirm that this is the date that the contents will expire. If it is not found, proceed to step 3.
Look for the words "Mfg Date," or "Manufacturer's Date." This is the day that the cylinder was made. The type of gas that your cylinder holds determines the expiration date. If it is an LEL mixture or Non-Reactive mixture, then it expires three years from the manufacturer's date. If your cylinder contains H2S, S02, NO, H2S-mixes, ETO, NH3, Benzene, or HCN, then you have one year from the manufacturer's date. CL2 and HCL expire eight months after. With mixtures of NO2, SiH4 and Ph3, you are given six months from the manufacturer's date.