I have never used them for air, but have done water pipe repair with them in FL. They seem to work fine joining a pex patch to copper at each end.
Fast, clean, and a whole lot easier than a torch and solder up in a celing soffit when the new RO water system the city put in starts eating all the copper pipes in town.
They have a pretty good grip on the OH ring the use. I can see them good for 200 PSI as long as there is nothing in the pipe that would rot the rubber. . Just be sure the outside surface of your pipe is clean and dry.