The Venturi nozzle is a particular conformation of a pipe that utilize the Venturi (or hydrodynamic paradox) effect, the physical phenomenon discovered and studied by the Italian physicist Giovanni Battista Venturi. When a velocity increases, a fluid stream decreases in pressure . At a practical level this is a reduction in the pipe section (or in the increase of the same, in this case the pressure increases and the speed decreases). It is a component in self-priming pumps (e.g. our JET pumps).