[PSUBS-MAILIST] G.L. summary Pressure Hull

[Sean T. Stevenson]

Is it possible that this rule is simply another way of stating that hatches need be designed to seal with pressure, such that they physically cannot be opened unless equalized (+/- a person's strength)?  Dogs in that case are just a means of providing a little bit of precompression on the O-ring in the absence of a pressure differential, and to hold the hatch against _slight_ reverse pressure, such at the 1 ATM specified by ABS.

ABS' version says that a means must be provided to equalize pressure before opening (needle valve?), that means must be provided to determine the pressure on either side, and that interlocks must be present to prevent e.g. submerging with open hatches.

I wonder if GL is really that prescriptive, or if we're misinterpreting?

Sean


Joe Perkel <josephperkel at yahoo.com> wrote:
>Alan<br/><br/>No definitive answer but we can postulate that both
>sensing and actuation are involved. <br/><br/>On sensing, differential
>pressure on either side of the hatch is translated to a impulse to
>actuation.<br/><br/>On actuation, a method of locking out the operator
>from physically un-dogging the hatch, is the only way to meet the
>standard as per your O.P.<br/><br/>Joe<a
>href="http://overview.mail.yahoo.com?.src=iOS"><br/><br/>Sent from
>Yahoo Mail for iPad</a>
>
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