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Diving instructor killed – incorrect valve threads

The Dutch Labour Inspectorate (Nederlandse Arbeidesinspectie) reports an incident in which a diving instructor was killed. The incident is reported here (in Dutch).

What happened

During a dive, the valve came loose from the diving cylinder and fatally hit the diving instructor; a cylinder with internal thread G3/4 was used, which was fitted with a valve with external thread M25x2.

What was the cause

Threads on the diving cylinder and the mounted valve were incompatible. In this case, the screw thread of the valve was slightly smaller than that of the screw thread in the diving cylinder. The result was that there was an increased risk that the valve will come loose from the cylinder when at pressure.

Members are advised to follow the guidance contained within IMCA D 064 Guidance on diving cylinder and valve thread compatibility. The Dutch Labour Inspectorate (Nederlandse Arbeidesinspectie) notes that despite various (international) publications about the prevention of such incidents, these situations unfortunately continue to occur.

Members may wish to refer to:

Safety Event

Published: 18 January 2023
Download: IMCA SF 03/23

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