Acetylene Cylinder “Loses Control”

Acetylene Cylinder “Loses Control”

“It was fortunate the accident happened outdoors!” This was the comment of our engineer who recently investigated a very unusual occurrence—the explosion of an acetylene cylinder.

An experienced welder had taken his two-wheeled cart outdoors to replace used cylinders. He put the new acetylene cylinder on his cart and opened the cylinder-head valve to blow out the dirt. Then he attached the regulator, and as he slowly opened the cylinder valve, the gage needle spun around beyond the pin to approximately 400 pounds, the normal being 240 pounds. Believing the gage, defective, the welder tried a new one. This acted like the first. He then became suspicions and reported the condition.

The cylinder became hot and everyone was wisely ordered back. Soon the fusible plugs melted; smoky soot shot twenty feet into the air; and within a few seconds the cylinder hurst with a report heard several blocks away.

After the Explosion in the Acetylene Tank

The explosion demolished the welder’s cart and threw the full oxygen cylinder some thirty feet, but fortunately it did not burst. The axle of the cart was blown through the air. struck an employee 200 feet away, and broke his leg.

This is the first case of its kind known to us in twenty years. Explosions used to be more common, but the modern cylinder, considering the thousands in almost daily use. has an excellent record of safety. When an explosion does occur, however, there is great possibility of personal injury and property damage. Acetylene cylinders are entirely filled with a porous material consisting of charcoal, fuller’s earth, and cement—the purpose of which is to prevent the existence of large voids. Liquid acetone, which will dissolve many times its own volume of acetylene, is pumped into this filler under pressure, and then acetylene gas is admitted and the pressure maintained until the acetone will dissolve no more gas.

All evidence being destroyed, it is not possible to state positively what caused the explosion. Presumably there was a void in the cylinder, which became filled with undissolved acetylene, the explosion then being due to the decomposition of the acetylene into its elements, hydrogen and carbon, which would produce heat and great increase in pressure. If a void exists, decomposition like this may be started by a cylinder being exposed to severe shock or the application of heat.

The following are suggestions for the care of acetylene cylinders:

Protect cylinders against mechanical injury.

Avoid rough handling.

Paint the bottom of cylinders to guard against corrosion.

Keep cylinders a safe distance from furnaces, radiators or other heat sources.

Avoid storage of large numbers of cylinders inside buildings.

Do not store cylinders where they may be continuously exposed to direct sun rays.

Keep cylinders in a vertical position.

Follow all special handling instructions, suggested by your acetylene supplier.

Reprinted from the November, 1942, issue of “Factory Mutual Record” published by the Inspection Department of Associated Factory Mutual Fire Insurance Companies.

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