X-Message-Number: 1810
Date: Tue, 23 Feb 93 18:00:16 PST
From:  (John A. Gregor)
Subject: CRYONICS in a very cold room...

Mike Darwin writes...

> For sometime I have wanted to test the workability of working in a
> -135*C environment.  We will soon have a large insulated cargo
> container dropped off here (4 inches of urethane foam on all sides) and
> it is already plumbed for liquid nitrogen refrigeration.  I plan to go
> into this unit after cooling it to -135*C wearing  heavily insulated
> garb over a heated flight suit.  Of course I will also bring my own air
> supply!  I want to see how long I can work and stay in such an
> environment before becoming uncomfortable.

Mike,

It sounds like an interesting experiment.  While I'm sure you have
thought about most of the safety issues already, I thought I'd climb up
to the peanut gallery and air my thoughts/concerns.

    [ Well, upon rereading Mike's note, I see that he isn't     ]
    [ proposing dumping N2 directly to the internal atmosphere. ]
    [ I guess I still had the pontoon scenario floating         ]
    [ around in my mind (no pun intended, really!).  So, in my  ]
    [ best Emily Latella impersonation: Never mind.             ]
    [                                                           ]
    [ I'll still sending this just in case it does become a     ]
    [ concern in future variants of the cold room.     -JAG     ]

My first concern would be about working in a nitrogen atmosphere.  As
you already said, an air supply is critical.  Loss of consciousness
occurs in only a few seconds as people unwittingly empty their lungs of
oxygen.  Is there a window or some other way someone could monitor your
status and retrieve you quickly?  Will they be suited up and ready to go
(since they cannot breath nitrogen either), or will they just rely on
holding their breath?  Flooding the room with outside air would probably
be best in the test phase.  Going in pairs would alleviate some of the
risk, but should there be a waekness in your breathing apparatus, you
both might succumb at the same time.  This has happened to many divers
(frozen regulators, bad gas mix, etc).

Another concern is with the ability of your equipment to tolerate being
cold soaked to -135.  Will regulators, valves or fittings freeze?
Will hoses break?  Many metals become brittle or weaker at extreme
cold.  If you are using a compressed air tank, make sure it can
tolerate the cold.  Remember, this equipment is keeping you alive.  And
any failure, even if you are only 5 feet from the warm, sunny, oxygen
rich outside world, can be fatal.  Also, how are you planning on keeping
your air supply warm?

Will water ice or CO2 ice buildup become a concern?

Take care,
-JohnG
-- 
John A. Gregor
College of Oceanography			 E-mail: 
Oregon State University			Voice #: +1 503 737-3022
Oceanography Admin Bldg. #104		  Fax #: +1 503 737-2064
Corvallis, OR  97331-5503

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