GC MS 5973N foreline pump turns off. Won't pump down.

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7 posts Page 1 of 1
When I pump down from the MS (as soon as I turn the power on) ,it shows turbo speed 100% but pump status "not up to speed" and turns off the foreline pump after about 7 mins.

What is going on?

I plugged the transfer line and the ion gauge show 3 x10-5 torr

When I pump down from the software, the MS can only reach 70% turbo speed, then foreline pump turns off.

Any reason for the differences and why pump down cannot remain?
Just wondering if this is a diffusion pump running on newer version of software. I know that can show a pump speed instead of temperature ready and it does things like that.

If it is a turbo pump and at 100% with the interface capped you should pull down to 10^e-6 levels at least.

Have you ever replaced or greased the O-ring seal on the analyzer chamber door? A piece of lint there can cause a leak and over time the O-ring can become dry and not seal well. I remove the O-ring and take a little Apezion-L grease and lightly coat my fingers and use that to moisten the O-ring, then wipe it down well with a Kemwipe and reinstall. Reinstall can be a pain as the O-ring stretches slightly and wants to be larger than the groove, but if you keep working it down it will finally seat in.

Shutdown usually occurs because the turbo pump is pulling too many mAmps and it shuts down to protect the pump and controller. If the foreline vacuum is good and there are no leaks then you have to suspect the turbo pump itself. They either fail slowly like this or very quickly, which the quickly is easier to diagnose.
The past is there to guide us into the future, not to dwell in.
James_Ball wrote:
Just wondering if this is a diffusion pump running on newer version of software. I know that can show a pump speed instead of temperature ready and it does things like that.

If it is a turbo pump and at 100% with the interface capped you should pull down to 10^e-6 levels at least.

Have you ever replaced or greased the O-ring seal on the analyzer chamber door? A piece of lint there can cause a leak and over time the O-ring can become dry and not seal well. I remove the O-ring and take a little Apezion-L grease and lightly coat my fingers and use that to moisten the O-ring, then wipe it down well with a Kemwipe and reinstall. Reinstall can be a pain as the O-ring stretches slightly and wants to be larger than the groove, but if you keep working it down it will finally seat in.

Shutdown usually occurs because the turbo pump is pulling too many mAmps and it shuts down to protect the pump and controller. If the foreline vacuum is good and there are no leaks then you have to suspect the turbo pump itself. They either fail slowly like this or very quickly, which the quickly is easier to diagnose.


Thanks for the info.

The MS is using a dry scroll pump and it's on a older version of software.

The turbo pump shoes 100% with 10^e-6 levels when I boot up from the hardware (although status still tells me turbo pump 'not up to speed', but only 70% with 10^e-2 when pumped down from the software. No clue as to why there is a difference. When bo

I applied Apezion-L grease to the o-ring and it did not make a difference.
Have you tried plugging the dry scroll pump directly into the wall and running it a while before starting up the MS? For trouble shooting you can find a power cord used for a laser printer, those are usually heavy enough, and they have the end that is shaped exactly like the outlet on the back of the MS so it works just like an extension cord. If it works like that, then maybe the scroll pump is drawing a little more power than the MS can handle which is causing it to shut down.
The past is there to guide us into the future, not to dwell in.
chemist23 wrote:
When I pump down from the MS (as soon as I turn the power on) ,it shows turbo speed 100% but pump status "not up to speed" and turns off the foreline pump after about 7 mins.

What is going on?

I plugged the transfer line and the ion gauge show 3 x10-5 torr

When I pump down from the software, the MS can only reach 70% turbo speed, then foreline pump turns off.

Any reason for the differences and why pump down cannot remain?



You have a leak problem. Then first of all adjust the mechanical pump connection. Change the o-ring of the vent valve and adjust this valve very well (The o-ring is the same for the injection port liner) When you adjust the side plate of the equipment do not do it with the screws, let the vacuum itself do it.

Disconnect the power cable from the mass spectrometer and the mechanical pump and connect these two to turn on the mechanical pump only for about 10 minutes, verify that there is enough vacuum to hold the sideplate adjusted with vacuum. You turn and connect the cables as usual and turn on the equipment. Please tell how you are doing with those tips.
chemist23 wrote:
When I pump down from the MS (as soon as I turn the power on) ,it shows turbo speed 100% but pump status "not up to speed" and turns off the foreline pump after about 7 mins.

What is going on?

I plugged the transfer line and the ion gauge show 3 x10-5 torr

When I pump down from the software, the MS can only reach 70% turbo speed, then foreline pump turns off.

Any reason for the differences and why pump down cannot remain?

Check two fans on the 5973. First check the cooling fan for the turbo pump. Its got to be working well. Also check the cooling fan for the electronics drawer. You can see it just below the sideboard shroud. If either of those two fans is not reporting the correct RPM, you will get this behaviour. The fans need to be a direct replacement and cost around $150 each. They are easy to install.
Yeah it will not operate if the electronics cooling fan or the turbo/diffusion pump fan are not functioning. They use a 3 wire fan to get a readback.

You really should NOT need Apiezon grease on this instrument. If you do apply it, use a very small amount.
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