Guy,
All depend on your work intensity and accuracy. Do not open
diff.pump at pressure above specified,? provide right water cooling
and heaters power, keep a specified baking pressure and it will work
years. Sometimes you need just add a little bit oil. If you see that
your diffusion pump losts its pumping speed or ultimate vacuum -
check and replace the oil. A good oil must be light yellow or clear.
If oil is very dark or black - replace it. If you see a black coated
spots inside the pump - your oil is burnt, carefully clean the pump
and replace oil.
Roughing pump is the same. There must be a glass window to monitor
oil level and its quality. Oil must be transparent (light yellow or
light brown). If it is brown and turbid - replace it. If it is dark
yellow,? turbid and looks bulbed - there may be a lot of water in
the oil, just let it to work a couple hours with opened gas ballast
valve to dry the oil. Roughing valve to your vacuum chamber must be
closed.
Hope it helps.
Vladimir
On 6/18/2011 2:26 PM, Guy Brandenburg wrote:
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How often do you experts clean out and replace the oil in a
roughing pump?
How about in a diffusion pump?
We did the Diff pump about 10 years ago, and found all
kinds of interesting stuff had fallen into the trap. The
roughing pump (a Welch, IIRC) probably hasn't been cleaned out
in over 20 years.
Guy
