Cleaning 5973 ax-65 Diff Pump

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

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So I am working on the diff pump of a Quality instrument (6890-5973) where the foreline pump was allowed to backstream oil into the diff pump. The pump is an ax-65. The instructions are very unclear how to take it apart. For now I just rinsed the insides with MeCl2 several times (the 5972 manual says use MeCl2, the ax-65 manual suggested acetone followed by isopropanol but I've found acetone especially tends to linger longer especially when I clean the inlet with it).

Anyways there is a fair amount of charred oil caked on the jet but I can't figure out how to get the cold cap off and disassemble it and ensure everything is aligned right when I put it back together. Do you think it is necessary?

Also how do you fill it? Just pour fluid in from the top? The manual mentions a fill plug but I can find none.
OK I got it apart but am having a lot of fun getting the burned oil of the stack pieces. There was a transverse screw with a 2mm hex that gets it off.

It is worse than I though a layer of black chared oil all over the stack pieces. I am currently sonicating in acetone as I am running low on MeCl2 and don't want that stuff's vapors floating around my lab. It looks like it is going to be a PITA to get it off.

Any tips?
The stacks work just fine with a black stain on them, no need to make it clean and shiny. Heavy residues can sometimes be removed with solvent, but I have had to actually use sandpaper to remove heavy char. It doesn't have to be inert at the end, it just has to cool the fluid and create a reflux to make vacuum.

The fluid is a glycol, so the acetone works better than MeCl2, I have also used methanol to help remove the oil. But when just changing the oil it is ok to leave a little residue in it. It also takes almost two bottles of fluid to fill it up.

When putting the stack back together, I just make sure that the side with the hole faces the rough pump connector. There is also a U shaped notch in the bottom piece that sits across the heater rod, but that is pretty obvious but if backwards it will put the hole in the stack 180 degrees off from the rough pump port.
The past is there to guide us into the future, not to dwell in.
Thanks for the reply I am just worried pieces will break off later and clog stuff. Given how expensive Santovac is I don't want to have to do it again. Do you think I could use abrassive slurry like with the ei source.
MSCHemist wrote:
Thanks for the reply I am just worried pieces will break off later and clog stuff. Given how expensive Santovac is I don't want to have to do it again. Do you think I could use abrassive slurry like with the ei source.


It should work. Anything that will knock it off will work as long as you remove any grit afterwards. Sonication could help also, or possibly try putting it in a beaker full of sand and sit that in the sonicator, or possibly in a coffee can and put it on a bottle roller overnight, sort of like a rock tumbler, that would polish it up pretty well I would think.
The past is there to guide us into the future, not to dwell in.
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