slurpee/icee machines use this as well. As an engine mechanic, ice pumping is also used sometimes in refrigerated cargo trucks. Usually these trailers are carrying certain chemicals that become percussive-sensitive (explosive) at higher temperatures, but can be transported normally if chilled a little bit.
FCB (frozen carbonated beverages, the trade term for Slurpee/Icee) machines are not under hydraulic pressure, though. There might be a small amount of air pressure because of the beaters rotating on the mix.
