Wikipedia
Piston pump
A piston pump is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases. The first piston pump (called siphon) was invented by Ctesibius
Usage examples of "piston pump".
Basically, each machine had a piston pump, which forced the fog fluid through an aluminum block heat exchanger.