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Proforma Safety, LLC Proforma PSI…when performanance counts Diver Oxygen Tank Fails While pressure testing a full 25 pack of oxygen, the valve packing nut, handwheel, and seat were ejected from the valve when it was opened, resulting in minor injury to the operator's hand. Upon inspection, it was determined that the valve showed evidence of dezincafication. The packing nut was ejected from the valve due to the valve expanding under pressure. For those who may be unfamiliar with dezincafication, we'll clarify: brass undergoes a process called dezincafication where the zinc, through a galvanic electrochemical process, causes layers of zinc in the brass alloy to selectively dissolve away. The zinc is corroded out and a honeycomb of copper is left behind that is then dissolved away as well. The unit in question was several years old. Our recommendation: all cylinder pack outlet valves should be inspected, and any valve older than 5 years should be replaced. Recommended actions include 1) a change in procedure in that all manifold outlet valves should be changed at the time of retest. 2) Materials used to make the manifolds on all equipment should be investigated. 3) Anyone opening and closing valves should be advised never to stand in front of the valve, but instead, stand to the side while operating the valves.
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