Chromatography Forum

Hello,
I have recently been put in charge of piecing together and get running an old workhorse HP GC/MS (5890/5970). I haven't gotten too far as the turbopump (TPH 050) is not getting up to speed-only ~50%. The turbopump was replaced with a spare (TPH 080) that came with all the other random spare parts. This newer turbopump is not moving the meter needle at all. Any suggestions?
Thank you.

Wait a second... you're handling equipment worth four-figure, so be gentle.

1.) How long was the first turbo pump mothballed? It's good practice to change the operation fluid reservoir ("Betriebsmittelspeicher") every six months and the bearings after three or more years of stand.
2.) Did you measure the fore vacuum for the turbo pump?
3.) Was a leak-check performed?
4.) Did you hear unusual operation noises from the turbo pump?
5.) Was the turbo pump shut down by the controller? The TCP040 used in the 5970 is very aging and tends to develop strange error vectors.

Did you check that the rotor of the second turbo pump was spinning freely? From your findings it looks like that either the motor of the turbo is broken or the bearings are stuck. In both cases it's time for a makeover by a specialist (or to put the unit back in storage with a nice note "broken").

True, lots of variables.
It's been a while since I have dealt with a 70.
Some of the newer turbos in the 5970 have ceramic bearings so you won't need to worry about oil ( depending on age. The Varian ones have ceramic, Edwards oiled.
Is the rough pump runnung and geting into the 10-3 T range?
Is there a big leak?

If you are in the states I suggest you contact Alpha Omega Tech in Briele NJ.

The GC/MS was in storage for a number of years (>5). I was told it was fully functional prior to storage. The rotors spin freely in both pumps. The oil was changed in the first pump. I do not understand what is meant by "did you measure the fore pump for the turbo pump?" Measured for what? The external pump pulls 700-750 torr. I am unsure of how to perform a leak check. The manual is vague about most things and I only have the hardware manual. I have been unable to find the other manuals related to the MSD. The turbopump does not sound as if it is turning on at all.
As of now, we do not have the rough pump's power coming from the MSD, it is plugged in separately. I turn it on/off when I press the "pumping unit" button. Is it possible that the turbopump would not turn on if the rough pump were not plugged into the port on the back of the MSD?
Thank you for all of you help.

A clarification at first: My point read "2.) Did you measure the fore vacuum for the turbo pump?".

The fore vacuum is provided by the fore-pump (usually a two-stage rotary vane pump) and should be within a range of 10^-1 to 10^-3 Torr so the turbo pump can speed up. If the fore-pump fails to provide a sufficient fore-vacuum, the turbo won't spin up at all or stall at a lower rotational speed (until the controller shuts it down). This can lead to extensive damage to both the turbo pump and its controller.

After some thinking I came to the conclusion that you should get at first a vacuum measurement device suitable for the range of 10 torr to 10^-3 torr, usually a Pirani gauge.
That way you can check the vacuum of the fore-pump and also do a leak check.

A usual leak check is performed as follows: You close all _inlets_ of MS (i.e. especially the transfer line) and pump it down just with the fore-pump while you have a vacuum gauge connected to the inlet of the fore-pump with a T-piece.

When you reach a suitable vacuum (i.e. around 10^-1) then you stop the fore-pump and check how the vacuum changes. The pressure will increase (i.e. the vacuum will deteriorate) as all surfaces of the MS did absorb water which evaporates at such low pressures. Nonetheless the increase of pressure should be very slow and steady. A quick increase in pressure hints towards a leak.

If you don't have and don't want to get a vacuum gauge there is another way to tackle your current problems:
0.) I have no idea if the TPH 080 was actually ever manufactured. Disregard this unit.
1.) Re-mount the TPH 050 with a fresh operation fluid reservoir. For details see the manual at [url]labspc200.rutgers.edu/manual/tphu060.pdf[/url]. This is really important! Check the O-ring for the turbo pump for any foreign material. If you find any, remove it with a lint-free tissue like ChemWipe.
2.) Cap-off the inlet of the 5970 (i.e. use a Vespel/Graphite ferrule without a bore, a so-called butt ferrule or connect a short piece of fused silica column that you block with an old septum).
3.) Re-start the MS and see if it gets better, though I doubt it.

I forgot the most important info.

Let the rough pump pull the analyizer into position. If you screw in the clips before pumping down the O ring may not seal correctly.
I agree that you should also check out the O ring very closely. Can wipe it with a kim wipe moistened with methanol. I've also been told you can coat it lightly with hi vac grease then wipe off all you can. I would try a new O ring before messing with the grease.

Did you change the controller when you changed pumps? A TPH 050 controller will not run a TPH 060 pump.

50% indicates that you have a controller issue, not a turbopump issue. There is nothing in the pump itself that governs the speed of the pump - the governance is all in the controller. I would assume, based on what you've written, that you have a functional 050 pump and a malfunctioning 050 controller.

In order to properly run a 5970 you'll need somewhere around 40-80 milliTorr vacuum from your rough pump. On a '70, insufficient roughing looks just like a turbopump issue - without a foreline gauge it's really hard to tell the difference. You potentially have a leaking rough pump vacuum line (seen it before), or a leaking connection. Can you hear the rough pump gurgling? If so, you have a massive leak - check all your connections.

You don't want to plug the rough pump into the back of the MS - that is a fused connection that only provides enough power to run an old E2M1. You need to use at least an E2M2 or equivalent to get decent vacuum - if you're not doing this, change out your rough pump.

As HB3 points out, always troubleshoot a '70 without a column installed - butt plug the transfer line. Also, if it's been stored, tighten down the transfer line nut - it uses a metals seat and over time they loosen. You can get replacement seats from SIS.

The '70 is a great box - we run 5 of them. Once you get the vacuum solved I think you'll be impressed.

@mckrause: The stock turbo pump controller of the 5970, called TCP 040 can control a TPH 060, as you can see in here.

@HbJ: That is what Balzers claimed, but we've had problems in the past with certain revisions of the TCP 040 controllers. There were two versions, and the older version has problems controlling the TPH 060.

@mckrause: He's actually using a TPH050 (see first post).

@HbJ: Which validates my first observation - that the issue is with his controller. I pointed this out in my original post. Controller issues with the Balzers/Pfeiffer systems weren't common, but they certainly occurred- we've changed out several.

What are the approximate rates which the vacuum should return to atmospheric pressure if there is a leak versus if there isn't?

Should I do any sort of maintenance such as cleaning the source or lens, replacing the filament, etc. considering everything was in storage for an extended period of time?

Well, the pressure should not rise more than 0,1 torr/sec.

And if you have at least one working filament I wouldn't do any cleaning or other operations as those are prone to introduce even more errors.