RE: [PSUBS-MAILIST] Soft ballast venting valve

["Brian Cox" <ojaivalleybeefarm@dslextreme.com>]

Jon ,
           Also,  if you figured that a shaft with a .005 gap  in a 1/4"
bore,  that would give you an area of  .005 x .78 (circumference of 1/4'
circle)  = .0039 sq in
  4450 lbs x .0039 sq in  =  17.35 psi    not bad for 10,000 ft down !

Brian

-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Jon Wallace
Sent: Tuesday, January 06, 2009 9:29 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Soft ballast venting valve



Brian,

My guess is that pressure gauges are calibrated for whatever opening is
physically provided on the measuring unit. So a pressure gauge intended
to measure PSI using a 1/4 inch hole would certainly indicate 4450 units
at 10,000 foot depth, but the actual force on the gauge itself would
only be ~219 pounds. The physics can't be denied. There are 16, 1/4inch
squares, in one square inch. Divide 4450 by 16, and you have the
pressure that ONE 1/4inch square tube will allow through.

I know we aren't talking about actual square tubes for this mind
exercise, but it's somewhat easier to think of in terms of squares.

Jon



Brian Cox wrote:
> Jay,
> I saw that figure in the book I quoted, " Man beneath the Sea" , I'm
> not sure they are refering to the actual pressure coming from the
> outside sea pressure. Perhaps they are refering to the pressure
> exerted by the plug outwardly against the wall of the opening. In any
> case there would seem to be frictional forces that would come into
> play in order to hold something in place under that pressure. The book
> did not explain that statement. I think the pressure would still be
> 4450 psi at that 1/4" hole. If you had a pressure gage on it would
> surely read 4450 psi.
> Brian




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