Are you leaving the Co2 device all assembled ? I have never used one but have all the stuff for it. I would just guess it would be a bad idea to leave it assembled. If I ever need it I would screw the release head onto the valve, screw the cartridge into the head and then activate the release head via its lever.
If your stuff is left disassembled until use then I got nothin and pardon my ignorance. Having never used an inflator it is in my interest to learn because my cartridges are just sitting there aging !!