X-Message-Number: 7679
Date: Tue, 11 Feb 1997 21:45:13 -0800
From: Paul Wakfer <>
Subject: Re: Technology Disclosure

Thanks for the compliments, Ken. Yes, the dewars are also sitting
on six inches of very low conductivity foam at the silo bottoms which
are 12" of reinforced concrete thick. The foam itself without any wood
is sufficient to hold the weight of the dewar fully loaded.
Unfortunately, we do not have room for further insulation on the actual
silo concrete walls. Maybe some would help, but I doubt that it would
help if we had to decrease the insulating layer next to the dewar wall.
There is a point at which the long-term saving vs initial cost benefits
comparison is no longer positive. 

     With respect to a longer gas exit path, that is something which
will happen automatically as the system is completed. I didn't mention
it before, but above the 6" foam dewar top which causes the gas to exit
down the outside of the dewar will be fire retardant foam (with
reasonable insulating properties) attached to the silo steel lid which
seals the silo by its rubber gasket and weight. Therefore, the only gas
exit path when we are finished will be out the emergency water overflow
pipe which exits onto the neighbors parking lot three feet below our
floor surface level. I expect that this will help a little. And yes, I
am actually hoping to get the boiloff rate down to a full 50% of
nominal, although I am not "counting my chickens".

-- Paul --

CryoSpan, Inc. low cost, secure cryogenic storage of biological material
1313 N Market St. Suite 3410, Wilmington, DE 19801-1151
Email: Voice/Fax:909-481-4433

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