Hi Folks,
First of all, I would like to thank all who have responded to my question.
Based on their valuable suggestion, the problem has been resolved and
VT is very stable. In case anyone may be interested in the question, I
have summarized the resolutions of all possible reasons for similar
VT-problems.
1. Gas flow fluctuates or pressure drops, heater will be automatically
turned off for protection, which can be monitored by EDTE recording.
A backup N2 gas cylinders or a backup tank rigged in line with a check
valve and a regulator set just below what you need for the Cryoprobe.
A ballast tank with a larger volume of air in the line that will
attenuate short pressure drops or spikes.
2. No gas flow caused by “accidental turn-off” or ice-blockage in BCU05.
Check out with building manager to see if there is any valve was
accidentally “turned off” due to whatever reason; check out if the
facility compress air dryer fails (“dry air” is not dry) and moisture
in the compress air freeze up which blocks the air flow (especially
the areas like Tallahassee with high humility in special season) . It
can be confirmed by turning off the BCU05 to get the problem resolved.
Actually, unless you are running experiments at temperature lower
than 290 K, or higher than 310 K, you don’t need to have the BCU05 ON
all the time.
3. Most of time, the problem discussed is due to above reasons.
However, out of date firmware of hardware may cause BVT problem as
well, update from Bruker.
4. If the problem can’t be fixed after trying above steps, then go
ahead to contact Bruker. A replacement of the BVT is needed.
Again, many thanks to Dee-Hua Huang, Mike Lumsden, Bob Berno, Tianzhi
Wang, Chris Canlas, Phil Dennison, Weixin zhang, Josh Kurutz, Gorge
sukenick, Martha Morton, Clemens Anklin, Neil E. Jacobsen, Guy
Bernard, Kz Shein, José R. Martínez, Tim Claridge, Matthias Findeisen,
Jerry Hirschinger, Patrick J.B. Edwards.
Cheers,
Banghao
>> -----Original Message-----
>> From: banghao chen [mailto:chen_at_chem.fsu.edu]
>> Sent: Friday, 13 June 2014 11:27 a.m.
>> To: ammrl_at_ammrl.org
>> Subject: AMMRL: AV-III: automatically Heater off / gas flow "Missing"
>> flashes on EDTE window
>>
>> Dear All
>>
>> our Av III 700MHz with Cryoprobe (topspin 2.1/BCU05/ dry air -VT)
>> recently encountered a VT problem:
>>
>> the heater automatically turns off ( especially at night !), "MIssing"
>> gas flow flashed in EDTE window. After clicking the heater, it turns
>> on, and the gas flow of 670 L/h shows up in EDTE window too.
>> Next night, same problem again.
>>
>> Has anyone met similar problem before? Any suggestion in addition to
>> replace the BVT3000 MAS?
>>
>> By the way, Our N2 gas line for cooling unit backup and shim cooling
>> was accidentally disconnected by mechanic personnel, but it's on now.
>>
>>
>> thanks,
>>
>> Banghao Chen
>>
>>
>> **********************
>> Chen, Banghao, PhD
>> Director of NMR Facility
>> Department of Chemistry & Biochemistry Florida State University
>>
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Received on Mon Jun 30 2014 - 07:09:00 MST