I recently ordered about 25 different o ring sizes of varying ID and CS (thickness) online and it made me wonder what everyone prefers for the material for the o rings you use?
The Frolic originally came with FKM (viton) o rings, which they said were not ISO safe but in researching I’ve found they actually are iso-stable. They switched to silicone o rings later which they said were iso safe, but silicone is porous and absorbs smell, so I got confused on the reasoning for the switch.
I found this site which lists o ring material stability for isopropanol and a variety of other chemicals which also shows FKM as equal or better than silicone for ISO resistance.
I don’t like that silicone gets softer and stretchier while it’s hot, so it seems like FKM is the best all around choice. I’m curious what leads everyone to choosing which material to use and why not go with FKM when it is generally food safe even if you don’t get the versions specifically labeled as food grade? I don’t understand why food grade is a consideration in vapes as much either, when off gassing seems to be the more valid concern.
Then there’s FFKM which seems to be top tier all around and food safe certified, but they are crazy expensive averaging around $20 per o ring.
Edit: I didn’t realize the chart in the link above won’t load in mobile browsers so here’s a snip of the iso compatibility for easy reference:
