[RASMB] Vacuum pump

[Christine.Wandrey at epfl.ch]

Dear all,

two weeks ago, after more than 8 years, the 
vacuum pump in our  XL-I died (the pump became 
very noisy).
The Beckman service first changed the motor. 
Though the first run after this reparation 
stopped after about 4 hours with the message that 
there was no vacuum after running about 4 h at 40 
000 rpm.
Then the service recommended to replace the old 
pump by a new one. We agreed and the service 
arrived with a new one. This one became very hot 
already during the test run. The service had to 
come again with a another new pump. With the new 
pump the 0 microns were reached after 20 nim. 
However, after the departure of the service, the 
subsequent run stopped after about 2 hours with 
the same message: bad vacuum.
The service came again now running the XL-I and 
measuring the temperature in the pump. After 
about 4 hours the pump/oil temperature approached 
75°C and stopped, with the consequence that the 
AUC stopped running too.
Having identified the problem there is my 
questing:  Is there a special pump type that I 
should request from the service in order to avoid 
this problem? Has anybody similar experience?

Thank you in advance for your recommendations.

With kind regards,
Christine
-- 
PD Dr.habil. Christine Wandrey, MER
Ecole Polytechnique Fédérale de Lausanne (EPFL)
EPFL-SB-ISIC-LMRP2, station 15
CH-1015 Lausanne
Suisse

tél: (+41) (21) 693 36 72 in CH J2 494, Station 6
  or (+41) (21) 693  96 61 in AAB 042, Station 15
fax: (+41) (21) 693 60 30