Safer valves for compressed gas cannisters

Louise Smyth

Industrial gases are widely used for cutting and welding, and the hazards associated with heat, flames and flammable gases are generally understood. However, less well appreciated are the consequences of a gas cylinder being knocked over, perhaps because somebody trips over a hose, a forklift truck knocks a cylinder or something falls against or onto a cylinder. In the worst-case scenario, the cylinder falls and, as it strikes the ground or another object, the regulator breaks away from the cylinder. If this happens, the cylinder becomes extremely dangerous. Because of the stored energy in the compressed gas, the escaping gas can give the cylinder enough energy to punch clean through a brick wall or steel partition; anyone in the vicinity is at grave risk of being injured or killed. Although this sounds far-fetched, there are documented incidents of this type, so the hazard is real. Any risk assessment should identify the hazard of a gas cylinder falling and the potential consequences as severe. Notwithstanding the potential for causing death or serious injury, the knock-on effects of this type of accident can force a small business to cease trading.

The British Compressed Gases Association (BCGA) publishes guidance for the safe use of industrial gas cylinders, reference CP7, The safe use of oxy-fuel gas equipment (individual portable or mobile cylinder supply), and this is the code of practice to which the HSE (Health and Safety Executive) defers in matters relating to gas cylinders. CP7 contains advice on the safe handling, storage and use of gas cylinders, which should always be followed. However, there is more that can be done, particularly to prevent catastrophic accidents involving regulators breaking away from falling cylinders.

ESAB EDGE Series regulators equipped with SLAM (Shock Limitation and Absorption Mechanism) technology are designed so that the only part of the regulator protruding beyond the cylinder profile is the control knob, and this incorporates a multi-layer shock zone (‘crumple zone’). If the cylinder falls such that the control knob is struck, it deforms and absorbs energy in order to protect the regulator components and prevent the regulator from breaking away from the cylinder, as well as protecting the cylinder valve. In some countries replacement control knobs are available so that the regulator can be repaired and reused, but in Europe the recommendation is to treat the regulator as a sacrificial safety component and fit a complete new replacement. Videos are available on the ESAB website and elsewhere showing what can happen if a gas cylinder falls over with a conventional regulator, and how an EDGE regulator with SLAM technology can prevent a catastrophic failure. SLAM technology was developed by Victor Technologies, which is now part of the ESAB Group.

A second type of accident that can occur with gas cylinders is oxygen-related fires involving cylinders containing compressed oxygen. Pure oxygen at high pressure can react violently with common materials such as oil and grease. However, ESAB’s Edge regulators are believed to be the only products of their type on the market that pass the Promoted Ignition Test described in standard ASTM G175 and meet the CGA E4 Heated Oxygen Impact Test. A patented particle trap captures contaminant particles and diffuses their energy, so they are incapable of reacting with the compressed oxygen and causing an explosion. Moreover, in the event of an internal explosion in the regulator, absolutely nothing is released, neither gaseous nor particulate.

Although there is no legal requirement to use regulators that exceed the relevant standards, it would be best practice to opt for the safest regulators possible. A regulator that meets the standards’ requirements will be safe under certain circumstances, but a risk assessment will show that using conventional regulators will not reduce risks associated with falling cylinders to as low as reasonably practicable (ALARP) – whereas an EDGE Regulator with SLAM technology will. Similarly, an EDGE Regulator provides additional protection against fire risks associated with particulate contamination. Importantly, while EDGE regulators offer several safety advantages over competitive products, their functional performance is actually better in some respects. Flow capability is exceptionally good across the full range of cylinder pressures, equivalent to that of a two-stage regulator. This means the operative does not have to continually readjust the regulator to suit the decaying pressure in the emptying gas cylinder, resulting in simplified operation, higher productivity and more consistent quality.


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