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RE: [PSUBS-MAILIST] Soft ballast venting valve



Jay,

Thanks for the correction on units, I know better.  As Jon pointed out, a square tube will experience a greater pressure due to its larger area.  Don’t think you will find many submariners using square tubing though. J

R/Jay

 

Respectfully,

Jay K. Jeffries

Andros Is., Bahamas

 

As scarce as the truth is, the supply has always been in excess of the demand.

    -Josh Billings

 

 

 

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of James Barlow
Sent: Tuesday, January 06, 2009 7:19 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Soft ballast venting valve

 


As the pressure is already in PSI then the force (pounds) pushing your plug out of the 1/4" leak is  the 219 or 275 pounds  not PSI.  whatever the math is (I didn't figure it out) but you have to apply that many pounds not psi.

Jay.  (B)



Jon Wallace <jon@psubs.org>
Sent by: owner-personal_submersibles@psubs.org

2009-01-06 17:11

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Re: [PSUBS-MAILIST] Soft ballast venting valve

 





Thanks for that Jay. The 125 pound figure didn't sound right to me
either and I calculated a pressure of 275.125 pounds for a square 1/4
tube, but was too lazy to look up the formula for a 1/4 round tube.

Jon


Jay K. Jeffries wrote:
>
> Some notes on this discussion:
>
> 1. I have had the opportunity to spend some time in a US Navy
> submarine damage control simulator as part of a team that took on a
> series of leaks. With a team, a lot more room than found in a PSUB
> (even a large one), proper damage control response resources, and cold
> water under pressure, we were hard pressed to stop a variety leaks
> that would be encountered aboard a submarine. It was very stressful
> but someplace in the back of your mind you knew that it wasn’t real,
> there was a hot shower waiting for you, and there would definitely be
> at least a cold beer at the end of the day. Aboard a typical PSUB,
> there has been little if any previous damage control training, there
> are few resources available to combat a leak, reserve buoyancy is at a
> premium, you probably don’t have someone to assist in combating the
> casualty, and it is VERY cramped.
>
> 2. The actual pressure behind a ¼” leak at 10,000 fsw:
> 1 fsw = 0.445 psi therefore 10,000 fsw equals 4450 psi.
> The area of a circle (A) equals π times the radius squared, where the
> radius in this case equals 0.125” resulting in an area of 0.0491 in.^2
> Therefore the pressure through our ¼” tube at 10,000 fsw equals (4450
> x 0.0491) ~219 psi.
>
> 3. A hatch that is leaking in shallow water may not stop leaking with
> an increase in depth as the inflow of water disrupts the seating pressure.
>
> Later,
>
> Jay
>
> Respectfully,
>
> Jay K. Jeffries
>
> Andros Is., Bahamas
>
> */As scarce as the truth is, the supply has always been in excess of
> the demand./*
>
> -Josh Billings
>




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