Chromatography Forum

The MS doesnt have enough Vacuum. Its even to less to make a leak check. I already replaced the pump and the vacuum pump with no change so i put the old one back in. I also checked the fittings of the cards that connect the quatropoles. I changed the lockage; put a plug on where the coloumn normaly comes in. My next stepp is to change the valve to remove the vacuum and hope it helps.

I guess if the Ion gauge is the problem there would be a normal resolution with a bad vacuum in the display right ? Also maybe a plossibility that the RF board calculates the vacuum wrong since it messures it in stepps to controll the vaccum pump. But the pump spinns normal.

Any suggestions ?

You have a massive leak somewhere - check all the flanges, transfer line seals, calibration vial holder etc etc.

Peter

What make and model MS are we talking about? Given that you are trying to do leak checking, I assume GC/MS. So, have you put a blind ferrule in the transfer line and looked at the vacuum? Can you install a blank flange in place of the transfer line? I assume you are getting an ionization guage reading? First check over the parts Peter listed. But sometimes a leak can still be hard to find. If so, you can take a wash bottle with isopropanol (not a smaller alcohol - we are going to depend on the viscosity of isopropanol here) and put a liquid film along the seals on the mass spec. When squirt a bit of isopropanol on the portion of a seal that is leaking - or isopropanol flows over the leak, it will plug or partially plug the hole before significant quantities evaporate into the mass spec. So watch the ionization guage reading for a drop in pressure, which may be only momentary, for a clue as to where the leak is.

A couple of cautions - 1) don't let the isopropanol wet things that should not get wet - like the electronics and wiring. 2) Isopropanol vapors are flamable, so use it away from ignition sources and keep the vapor levels low - as in: don't soak the whole instrument (or large portions) at once!

Thank you for your quick help so far.

Its our really old Varian 1200 MSMSM

I put a plug in the hole where the transfer line comes in. I already thought about the calibration gas, theres a pug in there too. The only "holes" that i didn't check so far are the onces where the CI gas normally comes in (its has an EI ion Volume in it now; with a CI a leak check wouldn't work anyway ). And the one where the Air comes in when you vent.

I assume that the silver blue "tubes" are some sort of valves ?

I will also remove the hose from the collisiongas. to see if something is going on there.

I have almost every part as replacement, except for the turbo pump and the RF Board.