Chromatography Forum

Currently we use tanked nitrogen to supply the sciex api 3000.
The instrument is only used from time to time, so to save gas we turn it off between uses. When we start it up, we seal the orifice with a bit of Teflon tape and we do a soft-start. When doing a soft start the curtain gas is left off. This saves us gas while the turbo pump spins up which can take a couple of hours.

I was wondering what the effect would be if the instrument were left running like this for an extended period, say over a weekend.
With the orifice sealed, would the vacuum generated eventually be enough to draw in oil vapours from the roughing pump?
Has anyone done this or know of any problems that have occurred because of it?

Alp

I can't speak for your specific instrument, but Thermo actually recommend sealing the orifice of their ion transfer tubes on their instruments when not in use (while leaving vacuum pumps running). Their engineers generally use a spare APCI corona needle for the purpose! It just reduces the amount of lab air (and lab rubbish) that the instrument vacuums into its insides.

Thanks for the feedback.

What model are you using? I would like to read up on how the vacuum system works if I can.
I assume it uses a roughing pump in addition to a turbo molecular pump?

If so, would you know if the vacuum line from the roughing pump to the instrument is closed once a certain pressure is reached?


Alp

Hi Alp,
I wonder if you are still working with API3000, I need help with vacuum
Can you contact: 702 686 7164
Bill