Dear Mike,


Have you tried the following?

Switch off the vacuum system completely. Remove the exhaust pipes/oil mist
filter/rubber hose/whatever from the roughing pump(s), ask someone in your
lab to put their thumbs on the exhaust nozzle(s) and switch the vacuum
system back on.

Keep the exhaust nozzle blocked for a few seconds (e.g. 10s), take your
thumb off and see if the pump makes a sort of belching noise. If not,
repeat.

All going well, this procedure should "kick-start" the pumps working again
properly. I noticed that after an unscheduled power-down, roughing pumps can
go into a sulk and when switched on don't do zilch though making all the
right noises. Having to work against a resistance seem to bring them back to
their sense however.

Good luck.

Wolfram


> -----Original Message-----
> From: Stable Isotope Geochemistry
> [mailto:[log in to unmask]] On Behalf Of Michael Cheatham
> Sent: 10 March 2005 13:26
> To: [log in to unmask]
> Subject: MAT 252 vacuum problem
>
>
> Hi,
>         We are finally trying to get the Stable Isotope Lab
> here at SU back up and running after a three year hiatus.
> The MAT252 has been running continuously during that time.
> Of course there were bumps along the way (BEE/BEF unit needed
> replacing and a few other problems), but overall the machine
> has been running fine.
>         We had a power failure last Wed night.  Our machine
> is on a Shunt Trip Breaker, so once the voltage drops below a
> certain level the breaker gets thrown off.  When I came in
> the following morning and tried to get the machine back up
> and running, the LED for the FV Inlet did not light, and the
> gauge when placed on FV Inlet remained all the way to the
> right.  I first thought it was a blow LED, so I replaced it.
> That did not solve the problem.  I then started checking
> pumps and everything was OK.  The Inlet Control screen shows
> the vacuum gauge between valve 39 and the ForeVac pump
> showing a constant 684 ubar.  I then suspected the problem
> was the vacuum gauge head, so I swapped it for another one
> and it worked in the new location.  I am at a loss right now
> in solving the problem.  Are the LED's on the front panel
> special?  I put in a 'run of the mill' LED (in the correct
> direction), but I'm now wondering if those LED's are special.
>  Have you seen this problem before?  Any advice?
>
> TIA
> Mike
> --
> ********************************************************************
> Michael M. Cheatham
> 312 Heroy Geology Laboratory                    Phone (315)-443-1261
> Syracuse University                                     Fax
> (315)-443-3363
> Syracuse, NY 13244-1070
>
> email:[log in to unmask]
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