Drying of Wet Chlorine Gas

[Harold]

A GC is used to determine concentrations of hydrogen, nitrogen, oxygen and carbon dioxide in chlorine gas. The chlorine sample is initially wet, and it passes through a drying tube containing magnesium perchlorate before injection into the GC.

My concern is that the perchlorate does not change color as it absorbs moisture. How do I determine when the perchlorate needs to be replaced?

- Harold

[AICMM]

Harold,

Have not done this analysis but I am being asked about something similar. What column are you using? Unfortunately, it may be a case where column performance is your first indication of a problem. The alternative approach might be to place an indicating adsorbent on the back side of your sampling valve and watch the health of that scrubber. You'll end up with some back pressure but that might be survivable.

Best regards.

[HW Mueller]

For drying gases I have used CaSO4 with some blue stained CaSO4 strewn in. The blue changes to pink when the capacity to trap H2O has been surpassed. The stained CaSO4 is commercially available, don´t have the catalogs here, but I seem to remember it came from one of the more common vendors.