Chromatography Forum

Hi all,

I have no UPS for my Sciex API-3000 MS. I was wondering if a power failure were to occur while it was up and running (at operating pressure) would it be damaging to the turbo pump?
The roughing pump is supposed to be run for several minutes (20?) after shutting off the instrument (and the turbo) because the turbo takes it's time to come to a stop.

Will the more "sudden" increase in air pressure due to having both pumps shut down at the same time potentially damage the turbo pump which will still be spinning ??

Alp

I would suggest that you contact the vendor. Over the years the reccomendatios on the turbos on my GC/MS system have been turn off the pumps and open the vent valve as soon as you want, then we were told to wait at least ten minutes, and reciently we were told that we could vent the system as soon as we stopped the pumps. The changes in guidance, I am told, are from the manufacturer of the pumps. The guidance changes...

Hi all,

I have no UPS for my Sciex API-3000 MS. I was wondering if a power failure were to occur while it was up and running (at operating pressure) would it be damaging to the turbo pump?
The roughing pump is supposed to be run for several minutes (20?) after shutting off the instrument (and the turbo) because the turbo takes it's time to come to a stop.

Will the more "sudden" increase in air pressure due to having both pumps shut down at the same time potentially damage the turbo pump which will still be spinning ??

Alp

Also I am told turbo pump is rather fragile that power failure may destroy it (just like the harddisk in your PC). I myself had several cases of power failure before a UPS was installed but the pump is still working (5973N).

Hello,
since turbo pumps always in high speed during run, any power cut would damage it. But not always. You can easily see this, when you start the system, if the turbo pump can not reach 100 % power, or can not maintain 100 % power, then it is damaged. Otherwise it is ok. To avaid this kind of damage, it is always told that, you should vent the system if there is power cut possibility. During vent process, turbo can be stopped slowly (in control). When the power failure occur, turbo try to stop quickly (like driving 150 mph and try to stop suddenly, venting allows it slowly)

Ayhan

I will note that I had three GC/MS instruments in a laboratory in florida (frequent afternoon thunderstorms resulting in outages). Each instrument had two turbos. I lost only one turbo during that time.

The lab next to me had an LC/MS for four of those years and I do not recall any losses of turbos there.

Rember, when you vent the instrument, you turn off the pump and then expose the instrument to atmosphere. While an LC/MS instrument has gas being introduced into the system during operation. On a power failure, this introduction continues - so it serves to break the speed of the turbo.

On restart, the systems I know start the turbos trough the normal start-up procedure (slowstart with steps up to full speed). With a GC/MS system, this is a non-issue, assuming you survived any surges or spikes in the line voltage. With an LC/MS system, it depends on the capability of the sytem to pump down with the front end of the system open to sample the LC eluent - but at worst case, the turbo controller should sense excessive load and shut down.

Having said that, it is your vendor who gets the latest guidance from the manufacturer - and it is the vendor who honors warantees and service contracts.

As a rule a turbo pump lasts longer if it is never stopped after it spins up to speed. In the real world a turbo is stopped and restarted. In a power failure the turbo stops very quickly from high speed, where if you let the pump spin down for 10 to 20 minutes, then vent the turbo stops quickly from a lower speed. I like the car braking analogy above, one panic stop from 150 won't cause the brakes to fail, but if you do this on a routine basis the brakes won't last too long.

A sudden stop will probably shorten the life of the pump, you have subjected the pump to additional stress. WIll you be able to tell the difference? All turbo pumps will fail eventually, it is very hard to predict how long an individual turbo pump will last. If you have frequent power failure you may have shorter turbo life than average, but with a few failures per year I doubt that you will see any effect.

Yes, I should have specified, if I did not...

The system I was asking about was meant for LCMS. It has a permanently open orafice, which allows a small but steady flow of gas into the instrument (mostly curtain gas, N2). And both turbo and roughing pumps are running when the instrument is operational.

Thanks for the feedback. I have been told it is best to leave the system running but as it is only used 2-3 a week or so during certain spells, and may be unused for long stretches between. I think I may be tempting fate by deciding to turn it off.

Of course leaving it running continuously for months on end increases the chance that it gets hit with a power failure, doesn't it?

I'll ask the manufacturer. Thanks

Alp

Note on my comment above - when i described current guidance as open the vent as soon as stopping the pumps: "stopping the pumps" is used by the service organization and user community of this instrument for turning the power switch off. So, the guidance is to open the vent know with the power to the pump turned off and the turbos still turning at close to full speed.

Turbo pumps have momentum, and will keep spinning for a long time, even when power is cut. As long as there is vacuum in the manifold, it's not going to get damaged. The vent valve should only be opened once the turbo speed is close to 0%, the source and quads are cool enough (for Agilent typically <90 C). Opening the vent valve while turbo is spinning introduces air into the system and may damage the pump. Why open it too early? For Agilent systems it clearly says to wait about 40 minutes for the vent cycle to complete. Only then one should open the vent valve.