[PSUBS-MAILIST] Diving bell hatches and mating devices which are not sealed by pressure are to be fitted with a locking mechanism which prevents opening under pressure. The locking mechanism is to be so designed that the correct closure position is clearly apparent before pressure is applied.

[River Dolfi via Personal_Submersibles]

Are you sure you are interpreting the rules correctly Alan? The only rule I
can find in GL requiring a hatch equalization lock is the following:

Part 3, Chapter 1, Section 3
"2.3.1 Diving bell hatches and mating devices which are not sealed by
pressure are to be fitted with a locking mechanism which prevents opening
under pressure. The locking mechanism is to be so designed that the correct
closure position is clearly apparent before pressure is applied."

This only applies if you're building a diving bell, recompression chamber,
or diver lock-out. In that case having the hatch open under pressure would
result in an explosive decompression, instantly killing everyone involved
in a nasty way. I would guess that this rule was implemented in response to
the Byford Dolphin accident (https://en.wikipedia.org/wiki/Byford_Dolphin)
where that exact scenario happened and would have been prevented by a
pressure activated hatch lock.

Thanks,

-River J. Dolfi

rdolfi7 at gmail.com
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