Skimmer-reducer cone

[Sedmic]

Hi,

We recently encountered an issue with our CyTOF 2. After performing a routine weekly cleaning, we reassembled the machine and successfully turned it on. However, Autotune failed repeatedly. Upon turning off the machine and investigating, we discovered the skimmer-reducer cone had apparently overheated and some of the rubber melted (see images at https://plus.google.com/116294381030215 ... gNN6o5ykkk). We _thought_ we had screwed it in completely but had intentionally not tried to lock it in. The sampler cone had no problems and the O-ring was intact.

Has anyone else encountered this problem before? How forcefully do you screw in the skimmer-reducer cone?

Thanks,

Ramin

[robs]

Hi Ramin,
We did have this problem, although only one corner melted. We got another skimmer/reducer and now I literally tighten it as hard as I can with two hands. Generally it seems you can tighten it as hard as you like and it will not get stuck, and that is what I heard from DVS.
After you get your new one you might want to lubricate it with graphite and try different amounts of "torque" before you go all out though, just in case your instrument is different.
Rob

[Sedmic]

Thanks for the response! Our CyTOF doesn't follow the rules, perhaps. The reason we tried _not_ to overtighten was because we once had a stuck inner cone and spent literally almost 2 hours trying to unscrew it, despite having marked the threads with a graphite pencil. We had to use the symmetric machined holes towards the end of the cone removal tool's handle to create a longer moment arm to unscrew the cone. In the end, I think we're going to have to find some middle ground here.
Ramin

[robs]

That does seem excessive, do you think you are getting sufficient cooling at your interface? Are there any burn marks on the sampler or insides of the interface?
Fluidigm probably already asked, but is your chiller working up to spec?
I always wondered what those holes in the removal tool were for.

[anitamkant]

The cones should be "hand tight".
If they are not tight then the skimmer reducer cones cannot get enough cooling (cooling is by contact) from the interface which is cooled by the chiller. You will see them meting.
If tightened with too much force they will get stuck. So it is necessary to strike the balance.

[vvanunen]

We also encountered a burned corner of the rubber isolation ring of the skimmer-reducer cone. They are sending us a new cone and apparently I also did not tighten the cone tight enough. I am weary about overtightening too and I am also still looking for the right balance there.

Vincent, the Netherlands.