X-Message-Number: 4295
From: 
Date: Wed, 26 Apr 1995 11:46:19 -0400
Subject: New CI cryostat

The new Cryonics Institute fiberglass cryostat, the R-12 (Rectangular,
12-whole body capacity), now in service with a full load, is performing a
little better than expected. (Our other patients are in the older units,
moved over from the old facility. All patients are now in the new facility in
Clinton Township MI.)

Boil-off is currently around 5 liters of liquid nitrogen per patient per day,
including transfer losses. 

Pump-down is not yet completed, and the top insulation is a temporary
styrofoam job, so final results should be somewhat better. Even as it is, it
is satisfactory; we had hoped for at least a 25% improvement over the
previous 7 liter standard, and we already have that and a bit more. Andy
Zawacki has done his usual meticulous job of fabrication, as well as
contributing to the design.

The new cryostat differs from our previous rectangular models not only in
having thicker evacuated perlite insulation--18" instead of 12"-- but also in
being hard shell instead of soft shell. This means we do not use internal
bracing between the inner and outer boxes to support the air pressure of
about a ton per square foot; instead we use reinforcing ribs on the outside
of each shell, reducing heat flow paths. Except at the bottom and top, the
only heat flow path is through evacuated perlite.

This cryostat is not quite as efficient in insulation as the MVE type
four-patient "Bigfoot" models used by Alcor (I think these only boil off 4
liters per patient per day), but we think the other advantages more than
offset this:

First, it is much more rugged, much less vulnerable to mishandling or
accident, and more easily repaired in-house if damaged. Second, the MVE type
units eventually lose adequate (very hard) vacuum and need
baking/pumping/getters to restore it, necessitating moving the patients
meanwhile. Capital cost per patient is about the same for the R-12 and the
Bigfoot, I believe, but our experience with the R-12 will allow us to build
another considerably cheaper. 

The MVE types may have some advantage in floor space required and in weight
(not as heavy); but the weight issue does not seem important, and if we build
larger units on the R-12 plan the floor space per patient will diminish (and
boil-off per patient will again diminish also). We also like the idea that we
are not at the mercy of any supplier; we build them ourselves. Incidentally,
the R-12 has a fire-resistant exterior coat. 

Of course, the R-12 type is not the last word. We have other ideas to try
also. And eventually there will be commercial availability of rigid open-cell
foam, which will be a great leap forward--perhaps the ultimate--allowing soft
shell rectangular construction.

R.C.W. Ettinger
Cryonics Institute


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