Hi Bernie,

It sounds like you've condensed some water in your IRMS by leaving the 
cooling water on in a warm (and presumably humid) lab. This will actually 
remedy itself although it will take some time. You can accelerate the 
process by closing the valves to any continous flow devices. If you can 
get the vacuum down to a level where you can turn the IRMS on, you can 
monitor your progress by looking at mass 18. In a case such as this, 
patience is your best ally.

Rich Berger

On Thu, 4 Aug 2005 12:54:07 -0400, Bernie Genna <[log in to unmask]> wrote:

>Hi All,
>
>      We have a Delta Plus XL Mass Spectrometer that we vented last week 
to
>replace one of the quartz spacers in the source. While all the parts we
>laid on the table overnight (we had to order the spacer), the cooling unit
>in our building failed and the lab temp got up to 85 degrees. We had
>inadvertently left our cooling water turned after venting the instrument.
>When we reassembled the source and tried to pump down, the source vacuum
>will only pump down to 5X10-5. Thermo said that the source flange clamps
>were overtightened and the knife edge seal that seals the source housing
>needed to be replaced. Well we finally got the source flange clamps (from 
a
>secondary source), and replaced the knife edge seal and see that the 
source
>vacuum is still 10-5. The forevac vacuum is normal (2X10-3). My
>question(s): Could the temperature difference between the cooling water 
(15
>degrees) and the air temperature (85 degrees) cause problems in the vented
>source housing and/or exposed flight tube?  Could the high vacuum gauge be
>faulty? Do I suddenly not know how to tighten a source gasket to get the
>proper vacuum?
>
>Any ideas will be very much appreciated.
>
>Bernie Genna
>NCSU
>=========================================================================