Agilent 7000B frozen - how to manually vent?

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

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I recently experienced losing connection to an Agilent 7000B (QQQ) that was connected to a 7890A GC. I rebooted the computer and opened MassHunter but I can only control the GC through the software. The MS fails to connect on MassHunter. When I go to Instrument>MS Show/Hide Status it says "MS is not responding. Check cables and power switch."

I tried pinging each of the IP addresses and all the pings got replies (GC, MS and computer). The MS seems to be communicating over the network, but MassHunter isn't able to reset communication with the MS?

The front panel on the MS that displays the values for the vac pressure and quad temperatures is frozen since it hasn't changed since time of losing connection. However I am able to switch through the MS parameters, Network, and LCP test items using the buttons on the front panel but I can't vent through using the front panel. The MS front panel also displays "GCMS Comm. Disable".

I've seen others recommend power cycling the instrument without venting but this contradicts with what the manual says:
Do not vent while the turbo pump is still spinning at more than 50%

Is there a way to manually vent the MS when it is pumped down without the use of MassHunter software? Other MS systems like Waters has a reset button that manually vents it in case of software communication error.

If anyone has any feedback I would appreciate it! Thanks
I would power cycle-I suspect you have a good chance of clearing the error that way. I'm not familiar with that specific error, but it clears up other oddball Agilent MS errors for me almost always.

The caution about "venting" with the turbo still spinning I'm pretty sure refers to opening the vent valve on the instrument. This is not something specific to the 7000 or even Agilent, but applicable to turbos in general-you CAN damage them if they ingest a significant amount of air while still spinning at operating speed.

When you power off the instrument, the turbo will start spinning down on its own since it's no longer receiving power, although admittedly it does take a good while for it to completely stop(10 minutes or better). With that said, unless you have a massive vacuum leak of the sort that would keep the turbo from spinning up to its design speed, you won't have enough gas leaking in to cause damage in the time the turbo is off.

Also, this is not directly applicable, but I have a somewhat more "primitive" Finnigan LC-MS with an automatic vent valve that opens 30 seconds after power is removed. The vacuum system-both the rough pump and the turbo pump-on that instrument are significantly larger than what you will typically find on a GC-MS, so I'd consider that a reasonable guideline for how long it takes(although I'd probably wait longer if doing it manually).

With all of that said, if you power off and immediately power back on, the rough pump should kick back on and keep the vacuum at least good enough for the turbo to operate safely until it either automatically cycles into pump down again or spins down on its own.
benhutcherson wrote:
I would power cycle-I suspect you have a good chance of clearing the error that way. I'm not familiar with that specific error, but it clears up other oddball Agilent MS errors for me almost always.

The caution about "venting" with the turbo still spinning I'm pretty sure refers to opening the vent valve on the instrument. This is not something specific to the 7000 or even Agilent, but applicable to turbos in general-you CAN damage them if they ingest a significant amount of air while still spinning at operating speed.

When you power off the instrument, the turbo will start spinning down on its own since it's no longer receiving power, although admittedly it does take a good while for it to completely stop(10 minutes or better). With that said, unless you have a massive vacuum leak of the sort that would keep the turbo from spinning up to its design speed, you won't have enough gas leaking in to cause damage in the time the turbo is off.

Also, this is not directly applicable, but I have a somewhat more "primitive" Finnigan LC-MS with an automatic vent valve that opens 30 seconds after power is removed. The vacuum system-both the rough pump and the turbo pump-on that instrument are significantly larger than what you will typically find on a GC-MS, so I'd consider that a reasonable guideline for how long it takes(although I'd probably wait longer if doing it manually).

With all of that said, if you power off and immediately power back on, the rough pump should kick back on and keep the vacuum at least good enough for the turbo to operate safely until it either automatically cycles into pump down again or spins down on its own.


I agree. The warning is about venting to atmosphere with a spinning turbo, not necessarily cutting power to it. I normally hit the power switch and wait 15 seconds then turn it back on and see if that resolves the problem. My 7000C has locked up like that a couple times and that usually fixed the problem. I did have once where I had to cycle power on the MS, the GC and the computer to completely clear a lockup. I have also had to cycle power on the Ethernet Hub to clear a problem like this. Usually a small power drop or spike causes it to happen.
The past is there to guide us into the future, not to dwell in.
Thanks Ben and James for your feedback. So to my understanding power cycling the instrument will clear its faults and as long as I don't open the vent valve while the turbo pump is spinning at operating speed, the pump will not be damaged. Is there a risk if I power cycle the instrument and it doesn't pump back down for whatever reason? Will oil be sucked into the MS?

I spoke with people who refurbish vacuum pumps such as these and they recommended that I disconnect the turbo pump controller and/or turbo power supply from the back and wait until 10min until it stops spinning. Then turn foreline pump off or powercycle it then, or machine will sense that it can't meet vacuum threshold which should shut the foreline off automatically. They said the only problem with turning off the MS at the switch is that they recommend that the foreline pump stays on WHILE the turbo is still spinning on its way to off. So it seems like you guys have turned all power off which also turns off foreline but you turn it back on wait a few seconds and power on again and this seems to not damage the instrument parts.

I am debating which one I should do:
1. Unplug turbo power and turbo controller, wait 10min until turbo stops. Then proceed with powercycling if it doesn't automatically sense it cant reach threshold and stops automatically.
2. power cycle the MS while turbo and foreline pump on. Do not wait too long to power on again so that foreline still is pumping down (15 second wait as james said or immediately as ben said).

James and Ben have you guys ever considered unplugging the turbo power and or controller first? These two options may essentially be the same?

Anybody have any other suggestions? Thanks so much for your feedback.
I wouldn't go to the trouble of powering down the turbo independent of the instrument.

For one thing, that's a lot of poking around inside the instrument, and not something I necessarily suggest doing without good reason.

I don't actually have an Agilent with a turbo(all of my Agilents are diffusion, and all my turbos are other makes) but it's not an uncommon situation to kill both the instrument power and the rough pump at the same time. I've both seen it done and personally done it on a variety of instruments, and it has never caused a problem. There again, the vacuum will still hold long enough for the turbo to spin down safely even without the rough pump running.

As a bit of another data point, the Varian 300 I got last week(GC triple quad) actually kills power to the rough pump pretty much as soon as you hit "vent" in the software. If there's any delay between the turbo and the rough pump being shut off, it's well under a second.

To add a bit more, though, on most of my MSs I power the rough pump separately from the instrument itself. That was suggested to me by an Agilent FSE several years ago when the pump went out on my 5975 and all I could come up with on short notice was a Varian DS102 that draws more current than the 5975 is rated to supply. I've since found that I actually like using a larger pump than Agilent generally specs :), which necessitates that, and I can also do things like power cycle an instrument without the rough pump shutting off.
I have never unplugged the turbo power. The 10-15 seconds it takes to clear and reboot the internal computer of the MS really doesn't give enough time to lose vacuum. The turbo will still be spinning above 85% speed which will make the instrument still think it is at full speed, a few seconds after power returns and it will be back to full speed.

If the rough pump or turbo does not recover, then there could be a problem with the pumps, which should be investigated as that could cause other electronic problems if one of them is pulling too much current for the system to be stable.

If you think about it, if a momentary disruption of power would cause the turbo pump to fail, then they would be replacing them after every power failure in the lab. As Ben has done, I also plug my rough pumps directly into the wall power, and with a battery backup power supply on the MS I can survive a short power loss without the instrument even knowing it, even though the rough pump stops for a few seconds. The battery backup keeps power to the MS, and computer long enough for our generator to kick in(about 10 seconds) and the runs just keep going.
The past is there to guide us into the future, not to dwell in.
I also use battery backup to the MS, Network switch, and PC; and have the rough pumps plugged into the wall. It is not a problem then to reboot either the GC or the MS or both to clear a fault.

I should add, I am using 5890/5971 and 6890/5973 systems. But I think the procedure should work for newer systems.
Just power cycle it. The normal vent cycle turns off power to the heaters and to the turbo pump, but keeps the rough pump on.

Powering off the entire system and allowing it to vent "manually" is not optimal but also not going to damage anything. Certainly in a case where you just need to power cycle, turning off power to the turbo and rough pump for 20 sec and then powering it back on is totally harmless.

As mentioned, just dont open the vent valve until the turbo has gotten down to a low speed (0 speed if you're patient and smart..) I have seen people repeatedly crack the vent valve to speed up the vent process---dont do this, it puts uneven pressure waves on the turbo as it is spinning down and can cause damage over time.

FYI the rough pump has an anti-suckback valve which should prevent back streaming of oil up into the GCMS. When the system is powered off and you are doing maintenance it is a good idea to test the anti suckback valve just to make sure it is functioning (and check for things like oil in the vacuum hose..)


The TQ has pretty much a full computer inside of it that is running linux, and then within linux the TQ firmware runs as an application. If the system is frozen it is likely that this PC just needs a restart, which will occur when you power cycle. If after power cycling (and letting it fully boot back up..) you are still having issues, call support. Most likely it will be just fine after reboot.
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