X-Message-Number: 18564
From: 
Date: Fri, 15 Feb 2002 10:25:07 EST
Subject: Platt & nitrogen

Platt writes:

>So, what IS the boiloff rate of CI cryostats? Apparently it is half of
>what it used to be, but this of course is a PR statement that does not
>provide meaningful data.

He has it completely wrong, as usual.

First, the boiloff rate of the cryostats has not changed, and no one paying 
attention would expect it to change just because of a new storage tank and 
distribution system.

What has changed is our cost of nitrogen. The new system allows fewer 
deliveries at lower prices, less labor, and a bigger reserve. Our cost of 
nitrogen per patient, previously around $1,000/year, is now around $500/year. 


Letting that be known is certainly PR, but not in a pejorative sense. It is a 
genuine improvement over an already good system. 

Not meaningful data? Lower cost and bigger reserve are not meaningful?

As to the actual boil-off rate, our cryostats average around 7 liters per day 
per patient, the newer ones better. Not as thermally efficient as the Alcor 
MVE-type, but the tradeoff is that ours are much more rugged, and if 
necessary we can repair them ourselves on site without removing patients. 

Also, with the MVE types, even a small leak can result in very quick total 
boil-off, an emergency situation. With ours, even if you take an axe or a 
sledge-hammer to one and manage to produce a large leak and total loss of 
vacuum, we still have over a foot of perlite providing insulation. We prefer 
that safety. (This is  not to imply that Alcor's aren't safe. They watch them 
carefully and have contingency plans for damage. It's just a different 
approach.)

In the world of commerce, there are three main types of cryogenic storage 
tanks. The smaller ones use a very high vacuum with multiple radiation 
barriers, the MVE type that Alcor uses. For intermediate sizes the usual 
choice is perlite with a moderate vacuum, which is what CI uses. (But our 
fiberglass and rectangular designs are innovations.) The largest tanks use 
ordinary insulation such as perlite without vacuum. If we grow enough, we may 
eventually get to that.

Note carefully: The cost of nitrogen is only marginally important. Nitrogen 
cost is only a fraction of the total overhead of an integrated cryonics 
operation. If nitrogen were free, our total expenses would be reduced 
significantly but not dramatically. Nevertheless, in a hunker-down scenario 
that could change, and of course all savings are welcome.

Robert Ettinger
Cryonics Institute
Immortalist Society
www.cryonics.org

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