Just an aside related to this thread… remember Kittredge’s one accident as described in his memoir? He had a slow air leak into the cabin during the dive, and upon surfacing blew out the K-250 hatch dome and found himself outside the sub having been blown out of the opening. That story was the original reason I installed two things in Snoopy, an altimeter and an overpressure valve. I would point out the two go together.
Alec
The contents of this e-mail are intended for the named addressee only. It contains information that may be confidential. Unless you are the named addressee or an authorized designee, you may not copy or use it, or disclose it to anyone else. If you received it in error please notify us immediately and then destroy it. From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Jon Wallace I think I'll add an onboard checklist for possible causes if the alarm goes off. This brings up the question: What level of cabin pressure increase should activate the alarm? I'd like to hear some answers on that one.
Sent: Tuesday, March 27, 2012 4:06 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Altimeters as leak indicators
Probably somewhere around 2-3psi I would think. Not sure about the rest of you but I have to start clearing my ears at around 6-8 feet of water pressure. If you need to clear your ears in a 1ATM during operations, that indicates a problem of some kind which should send you to the surface. The two main issues I can think of that you want to avoid is an internal pressure/dive duration that ends up requiring decompression; a high enough pressure level that introduces O2 toxicity. Both of those situations would be difficult to get to without the pilot knowing something was wrong since even without any gas monitoring you'd be clearing your ears plenty of times. Unless you are drawing a vacuum as part of the pre-dive systems check (like DW-2000 does) there should be no clearing of ears unless there's a problem maintaining 1ATM within the cabin.
Jon
On 3/27/2012 1:35 PM, JimToddPsub@aol.com wrote: