Hi, Ross - at first blush, yes. However, if
free flow happens (e.g.: iced over reg) the overpressure (relief) valve would
kick in.
If the diaphram breaks (poor maintenance?) all that
will happen is that some water will come into the cabin and wet your feet.
That's if the regs are kept low down at the floor. You'd lose the "lung"
function of your cabin, though, and the dive should probably be
aborted.
A way around this, in anticipation for that rare
day when the reg fails, would be to mount each reg behind a ball shutoff
valve. Of course, you'd have no way of knowing which valve failed.
Best thing would be to just shut off the master LP inlet valve to the cockpit to
save the balace of the air that's left and surface.
Rick L
----- Original Message -----
Sent: Saturday, January 21, 2006 8:43
AM
Subject: Re: [PSUBS-MAILIST] Ambient /
1ATM Q?
Aloha everyone,
I've been following what Rick and Joe and Bill are saying. It
sounds like the whole submarine depends on that little rubber diaphragm
inside a regulator. If it breaks or if the regulator starts to free
flow, couldn't you be in big trouble?
Ross Donato
Ah ha...now I understand! One little detail, (thru-bulkhead mounting)
makes all the difference.
Yes, that will work nicely!
Joe
From: "Rick and Marcia" <empiricus@telus.net> Reply-T! o:
personal_submersibles@psubs.org To:
<personal_submersibles@psubs.org> Subject: Re:
[PSUBS-MAILIST] Ambient / 1ATM Q? Date: Fri, 20 Jan 2006
23:59:29 -0800
Hi, Joseph . . .
Short answer: the cabin is at less pressure
(partial vacuum) than the surrounding water. Greater pressure
outside pushes in on the reg's diaphram since the lesser pressure is on
the mouthpiece side. Essentially the cabin is like your lungs:
drawing in air.
The regs will be mounted on the bulkhead with
the diaphram on the water side and the mouthpieces on the cabin
side.
I had a long answer! but the short one
works!
Rick L
----- Original Message -----
Sent: Friday, January 20, 2006 7:17
AM
Subject: Re: [PSUBS-MAILIST]
Ambient / 1ATM Q?
Rick wrote:
"I'd like to add to this by saying that a semi-dry ambient can
also use&nbs! p;this system. How? Once the required
amount of ballast water is admitted, you seal off the cockpit so
that the regs take over. Open the valve, the cabin is exposed to
surrounding water and the regs are disabled by default. Close the
valve, and the cabin pressure is now isolated and available to the
regs."
I'm sorry Rick, "explain it to me like I'm a two year old" Where
the cabin environment is concerned, where is the
negative pressure required to trigger the regulators on
descent?
I can see Chips membrane trigger working but, this I don't get
yet.
Joe
From: "Rick and Marcia"
<empiricus@telus.net> Reply-To:
personal_submersibles@psubs.org To:
<personal_submersibles@psubs.org> Subject: Re:
[PSUBS-MAILIST] Ambient / 1ATM Q? Date: Fri, 20 Jan 2006
00:23:40 -0800
Hi, Patrick, Bill, et al . .
.
I did not realize Rick and
Joe were using constant air flow in their ambient designs. Now I see
why their hull interiors are almost devoid of water
vapour.
Regarding constant flow: I'm
not sure if Joe is intent on using constant flow in
his sub or if he was using the term by way of
explanation.
My ambient will use a bank or manifold,
if you will, of regulators. There will be no constant
flow. The regs I'm talking about are standard scuba and are
sometimes referred to as DEMAND regs (as opposed to CONSTANT
FLOW). By only demanding air when you need it you save
your supply.
As Rick pointed out earlier
this can be handled by dessicant absorbant which is a powder which
absorbs water.and basically wicks water out of the air. The
air in their tanks is much dryer than normal air also so this helps
too.
I've
used the term "bone-dry" in previous posts
and, as Bill has pointed out, there really is little likelihood
of anything being bone-dry in a! sub cabin. I spoke in relative
terms. Desert air is considered "bone-dry" yet actually contains
a significant amount of water vapour. Just ask anyone who's had
to do a miliary survival course.
Magiacl Child's system will
be similar to using Barolyme to absorb CO2. Initially I had
intended on venting our (breath) exhalations directly from our
oral/nasal masks to the surrounding water. I've
since experienced an epiphany and am now thinking of simply
exhaling straight into the cabin. In this scenario, the
dessicant would simply absorb the water vapour from the cabin air (but
wouldn't purify it). The cabin's overpressure valve would
occasionally burp the excess pressure to the surrounding
water.
The down side, of cour! se, is that the
cabin air would be perennially stale and would support us
for less time should we need to stop using our masks. Exhaled
CO2 still contains a lot of O2 since the body doesn't metabolise all
the oxygen. So, there is still some breathing room so to
speak. Mind you, that's what pony bottles are for.
What all ambients have in
common whether they have an opening to the water (like in an upside
down glass) and use the rising water level to trip a float, valve or
sensor which then
activates their air tanks to vent, or
whether they are closed to the water and use a valve or sensor, is
that they use internal air pressure to push back against the external
water pressure
A
sealed cockpit obviates the need for a sensor of any kind since the
regulators themselves do the job for you (hence, the term
"regulator"). The demand regulator is a valve in itself.
The rubber diaphram in front of the mouth piece physically
pushes a lever that opens the valve.
I'd like to add to this by saying that a semi-dry ambient can
also use this system. How? Once the required amount
of ballast water is admitted, you seal off the cockpit so that
the regs take over. Open the valve, the cabin is exposed to
surrounding water and the regs are disabled by default. Close
the valve, and the cabin pressure is now isolated and available
to t! he regs.
Confused yet?
Rick L
.
----- Original Message -----
Sent: Thursday, January 19,
2006 11:40 AM
Subject: RE: [PSUBS-MAILIST]
Ambient / 1ATM Q?
Patrick,
As the question is specific to an ambient dry sub
which is my design profile, I will answer you in that
regard. Whereas a semi-dry or open ambient has a direct connection
to the outside ambient pressure, to remain a truly dry ambient
requires the use of check valves.
The pressure is equalized by a constant flow of air
introduced into the cabin which opens the check valves and dumps
the overpressure outboard. The outside ambient pressure does not
directly impact the cabin as you noted. There is a delay in
compensation, which limits descent rate to design structural
capability.
To oversimplify the 1 atm vessel keeps the pressure out
by the brute force of it's designed structural integrity.
Joe
From: "Patrick"
<pat_man_ta@hotmail.com> Reply-To:
personal_submersibles@psubs.org To:
<personal_submersibles@psubs.org> Subject:
[PSUBS-MAILIST] Ambient / 1ATM Q? Date: Thu, 19 Jan
2006 11:21:48 -0500
I am having some trouble wrapping
my head around HOW the outside pressure influences the
inside pressure in an ambient dry sub and how a
1ATM sub keeps the pressure out. Could someone explain this to
me?
-patrick
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