Hi spinlanders,
Our new 9.4T/20 MRI/MRS horizontal magnet (installed 2005) has a higher
helium boiloff. The manufacturer told me today that the cold head
inside the magnet is causing the problem (the cryomechanic compressor is
working fine). The remedy to fix the problem is to ramp down the magnet,
replace the cold head and ramp it up again. I was told that they have
done this same precedure on other systems quite a few times now. I am
not commited to it yet and would like to hear your opinions on the
followings:
1) The precedure to fix the problem seems straight forward, do you see
any potential problems? What to look and watch out for?
2) Is this going to change the room temperature shims? Should I ask them
to check and re-adjust the room termperature shims if necessary becasue
of ramp-down and up. This would be a good time since I am experiencing
shims change recently for this magnet, which I beleive is related to the
decommission of our 4.1T human magnet. (When this system was installed,
it is within 10-20 gauss line of the live 4.1T human magnet).
3) The magnet is under warranty. Is it reasonable to ask for an extended
warranty on the magnet system? if so, for how long? 1 yr from the date
it is fixed, or from the warranty expires?
4) The higher helium boiloff was first started when the cryocompressor
was downed becasue of power loss. The cryocompressor is not on a UPS and
we experience power loss quite a few times a year. Do you suggest to
get a UPS for the cryocompressor?
5) Anyone in this group has the similar problem?
Your inputs are highly appreciated!
Huadong
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Huadong Zeng, Ph.D.
Research Instructor
Division of Hematology/Oncology
Small Animal In Vivo MRI/MRS Imaging Facility
Comprehensive Cancer Center
University of Alabama at Birmingham
828 8th Court S.
Birmingham, AL 35294
Tel: 205-934-0265
Fax: 205-934-7367
Email: hzeng_at_uab.edu
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Received on Thu Feb 02 2006 - 17:06:04 MST