Hello Huiming

We've no end of problems with power disruption which is still on going
until February.
Are both turbo units not attaining speed? If so, something is leaking
(valve) maybe open somewhere? We had this on our 253 because the air line
which supplies the pneumatic valves had not come up to pressure after power
shut down. The backing pump pressures were OK. On the turbos themselves,
when were the oil pads changed last?
The MAT-900XP (organic) we have which is still in warranty, we've had 4
turbos go down for various reasons mainly bearings or drive magnets on the
TMH-071P pumps. We bought a monitoring and diagnostics unit, a DCU-001, on
the advice of Pfeiffer and I can provide information on this if you wish.

Regards

John

At 22:16 10/01/2005, you wrote:
>Dear folks:
>I found my turbo pump unit (TMH 262 and TMH 071) on the analyzer
>(MAT253) was off this morning. After   restarting, the turbo unit won't
>be able to attain nominal rotation speed, which means that I won't be
>able to check source pressure on the mass spec. The back pump (DUO 5.0)
>are fine (pumping down to 10 ^ -5 torr). No leak on the line is
>detected. A call to Pfeiffer did not seem to indicate that the turbo
>pumps are broken. The turbo pumps have been pumping for 2.5 years, and I
>don't expect their life is that short.
>
>I know several scheduled and unscheduled power outages during the
>holidays were partially to blame, but any suggestion how to fix the
>problem will be appreciated.
>
>Best,
>Huiming
>
>--
>Huiming Bao, Assistant Professor
>Department of Geology & Geophysics,
>E235 Howe-Russell Geoscience Complex
>Louisiana State University
>Baton Rouge, LA 70803, USA
>Tel: 225-578-3419 (office), -3413 (lab)
>Fax: 225-578-2302
>http://www.geol.lsu.edu/bao/

John Hill
Mass Spectrometry Facility
University College London
Chemistry Department
20 Gordon St.
London
WC1H 0AJ

Tel:  020 7679 4605
Fax: 020 7679 7451
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