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Let me clarify several of the points that Alec was making: 1. While
the standards for scuba air require almost no oil, a very minimal is
allowed. Only Class "E" air used in the mixing of NITROX is no
oil allowed. Small amounts of oil will accelerate the deterioration of
the LP and HP flexible hoses associated with a SCUBA regulator. 2. There
are two primary reasons for NO moisture in the air finally compressed into the
SCUBA cylinders: a.
On swift release of air from a
SCUBA tank as in blowing ballast at depth in an emergency instead of motoring
to near the surface, the adiabatic cooling will occur within the tank resulting
in condensation. This moisture does not subsequently become revaporized
when the tank is later refilled. The accumulated moisture will cause a
hastened corrosion of the tank interior resulting in a failed hydro or tank
failure. b.
If the gas expansion occurs under
low temperature ambient conditions, the moisture can freeze in the 1st
or 2nd stages of the regulator that is surrounded by air resulting
in an uncontrollable free flow condition which can result in rapid loss of tank
pressure. 3. SCUBA
tanks available from AGA are rated to 4,400 psi. 4. Studies
conducted in the 70s at the Respectfully, Jay K. Jeffries Ocean Engineer Andros Is., -----Original Message----- The attributes of SCUBA tanks air are basically... - Free of oil (because it would normally be breathed). Of course the ballast tanks wouldn't mind, but it would be a pity to contaminate
tanks with oil because they cannot then be used for breathing if you wanted
to do so. - Free of humidity; the problem here is simply that condensation in the tanks takes away from the tank volume. - Pressure, depending on the tank, is anywhere from about 2,200 psi to something like 4,000 psi. The ballast tanks don't care what you put into them. Diesel electrics can blow ballast with the exhaust gases if on the surface. It's just that when the container for your air is SCUBA tanks, then they have to be treated as such, which is pretty standardized. If a SCUBA tank
blows, it's pretty much like a bomb going off, so the folks who refill are pretty anal about tank inspections and such. The good news is the inspections are relatively inexpensive, and the same SCUBA shop that would fill your tanks will probably do them. Cheers, Alec -----Original Message----- From: owner- [mailto:owner- Kathy Sent: Friday, June 30, 2006 8:00 PM To: Subject: Re: [PSUBS-MAILIST] psub convention in Raystown Hi Alec, thank you for writing me. You are right on all accounts I am not a diver but I need
to ask this question; why scuba air for the ballast tanks? The power plant I
work at has air dryers and ultra fine filters for equipment and we also use a special filter/dryer set up for hazmat repair and rescue. I will ask
the safety guy who and where he fills the scba suit that I wear for emergency shut downs and hazzard releases.
I live in northern here. the original owner(he moved away) said that at the time of registration
(1983) the DNR said it was the only one registered in the state. But
who knows. The O-rings, gaskets, sealtite wiring, etc are going
to be replaced along with the plumbing , but I have to be honest with you on the view ports, there thirteen years old in beautiful shape (no scratches)
and havent seen the light of day since 1996. I doubt they will be replaced this year. The one dive I want to make before dog days turns the local lakes
green is a spot that I am familer with and is 15 feet deep, all sand with little weeds. If I enjoy the experience Ill keep at it, buy new view ports and support equipment, if I dont, its going on ebay. ----- ************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme- Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************ The contents of this e-mail are intended for the named addressee only.
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