James_Ball wrote:
Have you performed an Air/Water Check?
If you cooled the MS inlet down to 50c it is possible there is a leak at the nut as the vespel/graphite ferrule will shrink when heated and when the nut cools it will then for a leak. Start with tightening that nut 1/8 to 1/4 turn and see if that helps.
Hi James, thanks for your reply. I tried it and I think it fixed it or maybe I just needed more time as the next day it was at m59 Torr.
Something else that I notices is the H2O/N2 ratio. in my system N2 usually is the larger peak than water but it does pass tuning and leak check. this time water peak was larger. the oven was cold and I was thinking maybe the column attached to MS leads to a larger H2O peak. now the ratios are as before.
to be exact N2 4.96 E7 and the ratios are N2:H2O:O2 100:25:8.
Is this high N2 an issue? I use ultra high purity He and the color indication of filter is ok.
Sorry it might be long but I appreciate if you have any idea what is going on.