Inhaling Helium:Party Fun or Deadly Menace?
Cylinder Pressure Relief Devices
Buying Cylinders from Individuals
Cylinder Requalification Dates
Storage of Compressed Gas Containers
Compressed gas containers must not be exposed to temperatures above 125 F. Temperatures in this range can be met by exposing containers to direct heat, flame or temperature extremes. Temperatures above 125 F could result in excessive cylinder pressure and damage to the container's physical integrity resulting in a serious accident.
With winter months approaching, ice and snow may become a problem on containers. Avoid applying direct heat to containers to remove ice or snow accumulation. Allow ice and snow to thaw at room temperature.
Storage
areas must be well drained with good ventilation and preferably constructed of
fire resistive material. Storage area temperatures must not allow container
temperatures to exceed 125 F.
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Cylinder Requalification Dates
OSHA requires compressed gas cylinders in the workplace to be maintained in accordance with regulations of the US Department of Transportation (DOT). Among DOT requirements for cylinder maintenance is the requirement for periodic requalification for most cylinders. It should be noted that not every type cylinder must undergo periodic requalification, such as DOT 4L vacuum-insulated cryogenic cylinders.
For cylinders that are hydrostatically, ultrasonically, visually or otherwise requalified, a "test date" is marked on the cylinder, indicating the month and year of requalification, interpreted as the last day of the month indicated. The requalification date is not a "use by" date and DOT clearly states that cylinders whose requalification period has expired need not be removed from the workplace and emptied – they simply cannot be refilled until they have been again successfully requalified. Therefore, there is no need to return a cylinder to your vendor simply because it is "out of test."
The requirement to periodically requalify cylinders applies to cylinder owners. Even if you own your cylinder(s), your vendor cannot refill them beyond the expiration of their requalification dates.
Buying Cylinders from Individuals
It is not uncommon to find a good buy on a compressed gas cylinder at a yard sale, flea market, or from an individual advertising in a newspaper. Similarly, people sometimes inherit cylinders found on grandpa's farm.
According to the US Department of Transportation, a cylinder cannot be filled for commerce unless by or with the consent of the cylinder owner. Although this rule may not appear to have a safety aspect, actually it does. It is presumed that a cylinder owner should have knowledge of a cylinder's history, either directly or from the prior owner: how the cylinder was used and in what service(s), and the anticipated uses of the cylinder.
A compressed gas cylinder must be safe to fill with the intended gas. Your distributor must ensure that the cylinder is properly stamped with marking to indicate it was made according to US DOT (or Canadian) specifications or a current exemption, and that it has been requalified for use by an approved retest facility. The cylinder must be free from internal contamination, excessive corrosion, pitting or other defects which may compromise safety, and properly valved to include an appropriate pressure relief device. Buyer Beware. Feel confident that your seller can pass clear title, and try to learn something of the cylinder's history. Carefully examine cylinders for altered markings and obvious or hidden damage (be suspicious of new paint).
Cylinder Pressure Relief Devices
One or more of four types of pressure relief devices are used in most cylinders of compressed gases: (1) pressure relief valves, (2) frangible disks (caps attached to the back of valves which contain a small disk designed to burst at a specified pressure), (3) frangible disks backed with a fusible metal designed to melt at a specified temperature and (4) "fuse plugs" (threaded plugs resembling bolts, with a fusible metal core, designed to melt at specified temperature.
Pressure relief valves (commonly used on LPG gas cylinders) and fuse plugs (acetylene cylinders) may begin to function by leaking gas slowly. Frangible disks ("backed" or "unbacked") function by releasing the entire cylinder contents very quickly.
Never tamper with a relief device in any way. If a relief valve or fuse plug is releasing gas, do not try to "repair" it. Doing so risks creating an ignition, or may mask a potentially dangerous condition.
Move the cylinder outdoors if you can do so safely, mark it with a warning sign and instruct others to stay away. If you cannot safely move the cylinder, open doors and windows to increase natural ventilation and immediately leave the area. If you picked up your cylinder personally, do not try to return it -- call your supplier to replace the cylinder.
Portable heaters fueled with Liquefied Petroleum Gas (e.g. propane) are very popular in outdoor construction sites this time of year. To be used safely, both heaters and gas cylinders must be used and maintained according to their manufacturers’ instructions. Prior to use, inspect your equipment and your jobsite. Make sure the area is suitable for LPG use with sufficient ventilation.
During transportation and on the site, cylinders should be secured against movement and protected from damage. Most LPG cylinders are thin-walled construction, making them more susceptible to damage from falls or being struck by objects in motion. The relatively large diameter of many LPG cylinders does not negate the need for a securing device.
Homemade heaters and do-it-yourself repairs are strongly discouraged. Remember, you will be working with a highly flammable gas with explosive potential. Only trained technicians should attempt repairs using hoses, heating elements, and other materials specifically designed for LPG service.
Never allow untrained persons to operate LPG equipment.
Transfilling cylinders is serious business and should only be done by qualified people using equipment specifically designed for the purpose. Every year, our industry learns of a catastrophic accident caused by someone attempting to fill a compressed gas cylinder. This is not a do-it-yourself project!Oftentimes, one of the cylinders involved is an empty refrigerant cylinder. These cylinders are usually rated "non-refillable" due to lack of sufficient elasticity and tensile strength to withstand repeated fillings. Even refilling these cylinders with compressed air at low pressure poses a serious hazard.
OSHA has adopted the Compressed Gas Association standard P-1, "Safe Handling of Compressed Gases in Containers," which states:
"Compressed gases shall not be transferred from one container to another container except by the gas manufacturer using qualified trained personnel with the appropriate equipment and operation procedures. Transfilling of gaseous and liquid oxygen for respiration is allowed when permitted by the container owner and when done in accordance with CGA pamphlets P-2.5,...and P-2.6...@
Important: This information is offered by the National Welding Supply Association and Abbott Welding Supply as general guidance only and may not explain all relevant safety precautions or hazards.