Unable to pull vacuum - Quattro Micro

[pharm1]

After finally solving communication issues...I am attempting to pump down a "used" Quattro Micro that I have obtained.

The collision cell vacuum reading barely moves when I attempt to pump down, and stays as a positive valve.

The roughing pump starts and appears normal (I have tried 2 pumps with associated tubing) - so I don't believe there is a external leak or rough pump issue.

The turbo's reach 20-30 % speed and never get higher than that. They are quiet and again appear normal (at least according to a Waters tech who took a look).

The pirani gauge reads 1x10exp1 - 5x10exp2 - and moves only slightly towards negative pressure as I start pumping.

The operate light stay amber and constant and vacuum appears not to be achieved.

I did swop out the pirani gauge with a gauge from another quattro, and saw the same readings. So I don't think its a gauge issue, but I can't seem to see an obviously leak anywhere.

I am troubled as to why the turbo's never exceed 30% speed....any ideas....am I missing anything !?

Thanks in advance.

(I did have a Waters engineer pass through the lab yesterday and he saw nothing obviously and suggested I checked the Pirani (which I did), then look at the turbo's themselves (hopefully not the issue) or the motherboard !)

[sav]

Check leaks in vacuum system (carefully; from ion block to ...). May be you need to change some isolation rings.

[pharm1]

Thanks...I did start at the heating block and worked my way back to the 1st quadrapoles and checked the o-rings and seals.

Nothing looked out of place and o-rings looked good.

I can't understand why the turbo's never get past 30 % of full speed.

Thanks for your suggestion.

Mike

[mhr311]

The Micro uses the Edwards Split flow Turbo which may have a solenoid operated vent valve attached. Make sure the 24V rail is present and working (magnetic). You can remove the source cone and block with something like a GC septum of appropriate size since that component might leak too much. Check the Collision gas inlet valve (should be closed). Finally you can unplug the turbo controller and try pumping with the E2M28 pump alone, leak checking from the rear forward. Would be best if you could plug the 230V rotary pump into a external power supply and just attempt to pump down, after blocking the turbo vent valve.

[pharm1]

Thanks for the information.

Does anyone have an image of the solenoid operated vent valve or a description of its location ?

For one brief moment today, the turbo's came up to full speed and the instrument pumped down, (this happen when I switched the ethernet cables on the analyzer and collision cell pirani guages - the orange operate light never turned to green - so the instrument vented - and of course now, I can get it to repeat this !) - Maybe it was just a co-incidence that I was messing with the pirani's.

But I am now more sure that I don't have any leaks, and I am starting to wonder if my vent valve is not closing, hence not pulling any vacuum at all. And that once I just stuck lucky when I was under the hood tinkering and got the valve to close and it pumped down to 1x10exp-4 and appear stable.

Thanks again for your help

[mhr311]

For the Edwards Split flow Turbo see Edwards document B756-01-880. Note that the Compound Split flow Turbo, found on larger Triple Quads such as Agilent 64xx series is document B756-00-880 and not applicable here. Before going further, suggest power down the system, reseat all PCBs and cable connections at both origin and destination and then power back up. Note the Turbo controllers have a series of LEDs indicating state of the pump. All of the solenoids are the same, a small rectangular black plastic box mounted at its point of action, with a 24V wire attached. They are found on the CID input, N2 input as well.