Hi,

It is only changed when it looses it's properties (viscosity). So it is
dependent on the usage of the machine.

When it has been observed that base vacuum (pressure reading and time required
to achieve) is not coming up to the mark, first vacuum should be checked only
with rotary pump. If that comes ok then the oil quality of the DP (Diffusion
Pump) should be checked.

Sometimes we require to add the oil, or we feel that oil has become less viscous
and dirty we need to change it.


Thanks & Regards;

Ms. Purvi Kikani
Facilitation Center for Industrial Plasma Technologies
Institute for Plasma Research
Gandhinagar, Gujarat, India
Phone # +91 079 23269033 (O), +91 9979704390 (M)
email: purvi@ipr.res.in



--- On Fri, 10/7/09, Nataraj  wrote:


From: Nataraj 
Subject: [mems-talk] Frequency for changing Oil in Oil Diffusion Pumps
To: mems-talk@memsnet.org
Date: Friday, 10 July, 2009, 5:47 AM


Dear All,

              Can any one advise me, what is the frequency for changing the Oil
in Oil diffusion pumps?  Is it time based or does it depend on the utilization
of
the machines.

Regards,

Nataraj Santhanam
Sputtering Section