Quest 1: The range from 30 to 60 is affected predominantly by the
oil. A periodicity is also attributed to the oil contaminants.
Quest 2: Yes.
Quest 3: You do not need to put any sieve trap, but replace the rough
pump and heat out your flight as uniformly as possible at least over weekend.
At 17:11 2011-04-11, you wrote:
>The rough pump on our continuous flow MAT253 died last week. It was
>sudden enough that significant vacuum still remained within the
>flight tube. The convoluted stainless steal tubing from the rough
>pump to the turbo contained a significant portion of the rough pump
>oil. Of course we did NOT have a molecular sieve trap on this
>system. The top of the convoluted tubing and the turbo itself were
>dry to the touch and did not appear to have had liquid pump oil on
>them. Now however, we have inflated backgrounds, with the needle
>valve closed, for masses 18, 28, 29, 40, 44, 45, 46, 64, and 66.
>While I am not certain what the exact composition of our pump oil
>is, it probably has lots of cyclopropane through cyclohexane. Since
>the turbo showed no signs of liquid oil I doubt I would see signs of
>oil in the flight tube and am thus looking for a sign of vapor oil
>in the flight tube. My first question then:
>1) What mass would be a good mass to look at for the presence of
>vacuum pump oil?
>I did a mass scan from mass 40ish to ~120 and found something I have
>not seen before...the presence of all masses on the 1e10 cup. Most
>are below 10 mV while scanning. The largest signal is almost 3 volts
>and is somewhere near mass 64. If interested, see here for scan images:
>Full range scan -
>Zoomed in scan -
>My second question then:
>2) Does the presence of all masses as in the above images indicate
>the presence of a soup, like vacuum pump oil, in the flight tube?
>3) What is your favorite molecular sieve trap for the tight spaces
>of Thermo instruments?
>Thank you all for your time.
>Earth and Space Sciences
>University of Washington
>Seattle, WA 98195
>[log in to unmask]
>This message was sent from my telegraph.
Dr. Stanislaw Halas
Mass Spectrometry Laboratory
Institute of Physics, UMCS
20-031 Lublin, Poland
phone: +48 81 537-62-75
fax: +48 81 533-36-69