characterised by the fluid medium being suddenly pressurised, e.g. by explosion

Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped > the fluid medium acting on the surface of the liquid to be pumped > characterised by the fluid medium being suddenly pressurised, e.g. by explosion

Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped (using only negative pressure F04F3/00; jet pumps F04F5/00; siphons F04F10/00) > the fluid medium acting on the surface of the liquid to be pumped (F04F1/02 takes precedence) > characterised by the fluid medium being suddenly pressurised, e.g. by explosion