The screw will get into rotation thanks to the medium passing through the device, which will then be transferred by the-said screws from one end to the other end of the measuring device. For this to be done, the pressure drop is essential and seen as a "necessary evil". This rotation can then be recorded by a sensor which, combined with the processing unit (software and hardware), will be able to deliver a measurement according to the flowrate, viscosity and size of the measurement chamber. ft