Dear Penny,
first of all, I would not insert a plug instead of the down-to-air valve, because if you have vacuum in your system and you stop the pumps and don't vent the system in time, the vacuum sucks oil of the rotary pump in your analyzer and ion source. And then you have really big trouble!!
If you want do it, you must vent it by hand.
The right connection for the down-to-air valve is more in the middle of the pump. The connections at the bottom are for cooling water.
There is a (red) LED on the down-to-air valve. If the voltage (+22 V DC) for closing it is on the valve, it should burn.
Did you use a new metal seal for connecting the turbo? Try to tighten the screws a little more if possible or try a new metal seal.
Another change is to check the tightness and the seat of the oil reservoir of the turbo.
At last I would check the vacuum system until the turbo pumps. Therefore disconnect the rotary pump and all tubes from the turbos. Make the tubes blind, connect a Pirani gauge to measure fine vacuum, if you have one, and plug the rotary pump to an independent power supply. If it's really tight, there should be no gurgle anymore.
Good luck
Franz
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Franz Buegger
GSF- National Research Center for Environment And Health
Institute of Soil Ecology
Ingolstaedter Landstr.1
D- 85764 Neuherberg
Tel: 0049 (0)89 3187 3403
Fax: 0049 (0)89 3187 3376
e-mail: [log in to unmask]
-----Ursprüngliche Nachricht-----
Von: Stable Isotope Geochemistry [mailto:[log in to unmask]] Im Auftrag von Penny Higgins
Gesendet: Donnerstag, 11. Januar 2007 23:46
An: [log in to unmask]
Betreff: [ISOGEOCHEM] Vacuum troubles
Hi all,
It's late and I'm tired and my Delta Plus XP is cheesing me off. I'm
sure I've simply done something stupid, but I can't think of what it is.
We had to send our turbo pump back to Pfeiffer for repair (bad
bearing). I just got it back and am putting everything back together.
So far as I can tell, everything is tight and connected as it should be.
I turn on the pumps and get the normal gurgle from the rotary pump.
No shock, it's been sitting idle for nearly a month. The turbos start
up, as the gurgle continues. The turbos run quietly as they do when
there is not a leak in the system, but the rotary is still gurgling
away. The fail-safe finally shuts down the pumps when the turbos are
unable to reach 70% (or whatever the cutoff is) of their operating speed.
Everything is tight, and the turbos don't howl like a jet engine as
they do when there's a leak in the system, so I'm at a loss. I've
checked to be sure the source is seated properly in the source
housing, and it's OK. The one thing I'm not sure I have attached
right is the down-to-air vent on the turbo. It looks right, but there
are so many washers and rubber rings that I could have it wrong -
could an incorrect installation be causing this problem? I suppose I
could check that by simply removing it and inserting the plug to see
what happens.
Is there anything else it could be? Could it be an artifact of the
rotary sitting for so long (I don't think so)?
Yarrrgh!
Thanks all,
~Penny
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Dr. Pennilyn Higgins
Research Associate
"SIREAL"
Stable Isotope Ratios in the Environment Analytical Laboratory
Department of Earth and Environmental Sciences
University of Rochester
227 Hutchison Hall
Rochester, NY 14627
[log in to unmask]
Office: 209b Hutchison Hall Lab: 209 Hutchison Hall
Voice : (585) 275-0601 Outer lab: (585) 273-1405
FAX : (585) 244-5689 Inner lab: (585) 273-1397
http://www.earth.rochester.edu/SIREAL/index.html
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