What happened? (1999) While arranging materials in the lab, a researcher bumped a full-sized (1A) compressed gas cylinder containing 95% oxygen / 5% carbon dioxide. The cylinder fell, breaking off the regulator at the cylinder valve outlet connection. Fortunately, the cylinder valve broke where it did (see photos below) and the main cylinder valve was closed so no gas was released. It was also fortunate that it did not strike anyone.
Why did it happen? The researcher recently moved to the newly constructed lab from another building. The facilities, including the gas storage room, where permanent cylinder chain restraints were present, were not quite complete (gas tubing to the lab was not installed). Due to the design of the lab bench (having a short lip), the researcher could not easily secure the cylinder to the bench using the lab's standard cylinder strap. The researcher did not realize that the cylinder restraint device was not truly secured to the counter.
How can a similar occurrence be avoided? Compressed gas cylinders must be secured at all times to prevent them from falling (Chemical Management Best Practices, Storage, Section 4.3.15). In this situation, specific cylinder straps are available for benches with shorter lips and cylinder stands work as well. Ideally, the researchers should not have moved into the lab until the facilities were complete.
Oxygen (PDF format) is shipped as a non-liquefied gas at pressures of 2000 psi or above. At these high pressures, a ruptured cylinder can become a highly destructive rocket and the released contents can present a severe fire hazard. Oxygen is non-flammable but readily supports combustion. All materials that are flammable in air burn much more vigorously in oxygen – some with nearly explosive violence. Even if compressed gas cylinders do not rupture in a fall, their mere size and weight can cause crushing injuries, damage equipment and materials, or cause secondary accidents.
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Above Left – Broken cylinder outlet from incident. Above Right – Example of an intact cylinder outlet.
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