X-Message-Number: 2187
Date: Sat, 1 May 93 14:48:33 CDT
From: Brian Wowk <>
Subject: CRYONICS Reply to Mike Darwin

Mike Darwin:
 
> At this point I feel there is little danger of Brian's system of
> sleeping bags only being adopted since virtually all cryonics
> organizations have seen the wisdom of pods and gone to them.
 
        The great benefit of thinking out loud in this forum is that 
your ideas are scrutinized and optimized by many minds.  The great 
risk is that from time to time your thoughts are exposed as foolish.  
Thanks to Mike for clarifying the importance of patient cassettes.
 
> I stand by my remarks about small plastic containers.  Also, these
> containers are liable to be glass brittle and/or spontaneously crack 
> at the temperatures being proposed for their use.  I think your best 
> bet would be to have cells and ballast compartments engineered out
> of welded polypropylene.
 
        In my most recent message on the subject, I too have rejected 
small plastic containers in favor of *large* plastic containers.  I 
think the removable ballast should be in 20 gallon (160lb) cylindrical 
plastic barrels (which, if I'm not mistaken, are made from 
polypropylene).
 
        I believe the permanent ballast should be in the form of 
pillars distributed throughout the room.  Pillars of ballast are 
better than walls of ballast because they are less prone to flexing 
under loads.  (In fact, this is why pillars were invented.)  Pillars 
provide stronger vertical support than walls of the same weight.  
Pillars could be made by stacking ballast barrels within a bracing 
framework.  Alternatively, tall polypropylene tanks could be 
manufactured as Mike suggests.  Such tanks could be assembled and 
tested as discrete units outside the room.  This would be cheaper and 
easier than making extensive use of polypropylene as structural 
material within the room.
 
        Polypropylene might not be the final answer either.  My 
science encyclopedia notes that polypropylene exhibits "poor impact 
strength below -10'C."  We should freeze some plastic and steel 
barrels of water to -130'C in a LN2 dewar, and see how they fare.  If 
plastic doesn't withstand the punishment, we might find it necessary 
to use steel barrels for everything (including pillars).
 
                                        --- Brian Wowk    

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