UGA – Doty Probe Install

nstalled DOTY HX probe. Lineshape was marginal, as was S/N. Had to install sample from below like a solids probe. Was unable to get it to work with the upper barrel and sample eject because the probe is longer and has too much air leakage. See message below sent to DOTY.

Judy, I was assisting Audie Roberts at UGA in installing the Doty 5mm H-F, X 5mm PFG probe on his 600. We were able to get the probe installed using the sample holder and inserting it from the bottom of the magnet. But, when we tried to use the Varian upper barrel assy. To insert the sample from the top, we could not develop enough pleasure to eject the sample.

We removed the upper barrel and probe assy. From the magnet and hooked it up to test the eject. We also did this with a Varian probe. This is what we found. The Varian probe still ejected fine. The Doty probe would not. We noticed two things. One, the brass sleeve is about 5mm shorter than the depth of that part of the Varian probe. This means that the upper barrel does not go into the Doty probe as far, which I believe allows more air to escape. Also, and even more dominate, the brass sleeve has a gap between it and the silver probe shell. This allows a significant amount of eject air to escape. We tested this theory by sealing the gap during eject and the sample would eject. It still required more air than the Varian probe.

I have attached a couple of pics. One showing the Varian probe mated with the upper barrel, and the other the Doty probe. Maybe a solution would be to extend the brass sleeve by 5mm and to also fill the gap with RTV? Any other war to reduce the eject air leakage would improve the eject function of the probe. If you have any questions, let Audie or myself know. Thanks.