[tomkinstinch]

I wonder if a pump like this could be made smaller using a perfluorocarbon liquid like FC-70 (Perfluorotripentylamine)—nearly double the density of water, higher boiling point, non-flammable, and would not impart water vapor to the compressed air.

[chipsa]

I wouldn't necessarily be able to say whether it'd be smaller, but it'd probably work. It works due to the air getting entrained in the liquid as it increases in pressure. So there shouldn't be a requirement that the air dissolve into the fluid or anything like that.