Vacuum problem on agilent 7000

[Paula05]

Hi,

I have a vacuum problem on my agilent 7000 mass spec. I know the rough pump is working as I have switched them over onto our other instrument and the pump is working fine, so I have both pumps working. When I go to pump down the chamber door to the ion source will not vacuum shut. On masshunter, the pump down screen says that the High Vac is off. I have checked connections, I plugged the rough pump into the the wall instead of it getting its electrical supply from the mass spec in case there's a communication error and it is still not working.

Any ideas? please?

[Rndirk]

When you press pumpdown, you need to apply some force on the side door until you hear the pump making a kind of acceleration sound. Press where the screw is but don't screw it.

If you can't start the vacuum this way, you need to check the side ring and maybe wipe the ring around the chamber with a clean tissue dipped in some MeOH.

[Paula05]

Hey,

Thanks for your reply, I have tried this and I am still not having any luck. On the pump down screen I have 2.10E+4 mTorr for Rough Vac and the High Vac is at off.

Do you think it could be some electrical fault that is causing this?

[James_Ball]

One problem I had once was the spring loaded ceramic interface tip was not sliding as it should and would keep the side plate from closing completely. Open it up and with gloves on, push in on the ceramic tip and see if it will slide smoothly back to reveal the end of the column. If it is binding it can prevent the door from closing.

[Paula05]

I have checked and there doesn't seem to be anything blocking the door. It isn't just the source chamber door, there's also not a vacuum on the multiplier chamber door.

[Paula05]

Just an update on this, managed to solve the problem. It seems that there's a problem with the sensor on the mass spec maybe.

I plugged the power source of the rough pump into a wall socket instead of getting power from the mass spec. Whilst the mass spec was off, turned the rough pump on and it created a vacuum. Quickly plugged the pump into the mass spec again and turned the mass spec on and it has maintained a vacuum. The turbo kicked in and it is pumping down as it should.

Thank you for your help

[James_Ball]

Just an update on this, managed to solve the problem. It seems that there's a problem with the sensor on the mass spec maybe.

I plugged the power source of the rough pump into a wall socket instead of getting power from the mass spec. Whilst the mass spec was off, turned the rough pump on and it created a vacuum. Quickly plugged the pump into the mass spec again and turned the mass spec on and it has maintained a vacuum. The turbo kicked in and it is pumping down as it should.

Thank you for your help

When we first got our 7000 it would shutdown over night. There is a standby setting on the vacuum that if activated will cause it to shutdown after a certain time period of inactivity. We also had to have the power board replace at install as it would do a similar thing with turning off power to the pump. If the pump is pulling a little too much current at startup it could be causing the power board to shut it down which could either be the pump or the board being bad.

After replacing the board in ours it has run with no problems for three years now.

[Paula05]

Great, thank you. I'll see if we are able to check that and get it replaced.

[Paula05]

I now have a massive air, water and nitrogen leak and haven't a clue where it is coming from. I've done the obvious checks throughout the GC and it is still coming back with a huge leak. I've compared values to my other instrument and the only difference I can see is that the High Vac value is 1.56e-5 Torr on the instrument with the leak and 8.04e-5 Torr on the instrument without the leak. Any ideas on what this could be?

[James_Ball]

Do you have the collision gas or quench gas turned on? If so turn it off and see if the leak goes away. Could be a leak in that part somewhere.

You can also use a can of Dustoff computer duster and spray around both door seals and the column inlet inside the oven while doing a scan in manual tune and watch for large ion spikes in the 50-100amu range. If you get a spike then you have located the leak.

[Paula05]

Hi, terribly sorry for the late reply.

Thanks very much for your advice but it was just a glitch with the program. There wasn't actually an air leak so that was a whole lot of wasted time.

Thanks again. Fingers crossed it is all working rather well at the moment.