Brent,
This goes against basic physics. If you have only a
partial fill of a volume at depth, you will accelerate as you near the surface
and pressure drops unless you can vent the expanding air (you will find this
difficult as you manage all of the surfacing functions). You should
always size your relief valves to be able to handle the maximum expansion rate.
R/Jay
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
Talk sense to a fool and he calls you foolish.
- Euripides (484 BC - 406 BC)
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent
Hartwig
Sent: Friday, September 05, 2008 12:37 AM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Venting an Ambient
I forgot to add that,
if I need to blow air into the inflatable pontoons to surface, that I can add
just enough air to make the sub start to ascend, much like some PSUBBERS
do with there MBT's. That way as I rise, the air will fill the pontoons,
hopefully slower, and also keep my sub from accelerating as fast in a dangerous
manor, and put less pressure on the interior surfaces as the air expands and
tries to get out of the expansion valves. If I'm really deep then I'll need a
better valve design to deal with the faster changing pressures inside the
pontoons when they get totally full and the sub starts to accelerate. But I
still expect to need a number of expansion valves regardless. I would
hate to have the pontoons pop when ascending, it they are my last option for
lift.
Your expanding air filled dreamer ;)'
Regards,
Szybowski
From: brenthartwig@hotmail.com
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Venting an Ambient
Date: Thu, 4 Sep 2008 16:13:52 -0700
Hi Joe,
This point
you made below, is exactly what I want to figure out for my inflatable
pontoons, so I can blow them at depth if I need to in an emergency. Most
of the time I would only fill them up when I get back to the surface.
"What would a cracking pressure of 0.5 to 2 lbs translate to in hull
overpressure, and how many would be required to dump expansion in an emergency
ascent from max depth."
Your resident pontoon dreamer ;)'
Regards,
Szybowski
From:
joeperkel@hotmail.com
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Venting an Ambient
Date: Thu, 4 Sep 2008 13:59:49 +0000
Someone asked about venting an ambient.
I found some PVC check valves today which could quite possibly do the
trick but I think you would have to ask two questions.
What would a cracking pressure of 0.5 to 2 lbs translate to in hull
overpressure, and how many would be required to dump expansion in an emergency
ascent from max depth.
Otherwise, these look pretty nifty!
Joe