Screw-type flow meters are basically positive displacement flow meters. The machine has two measuring spindles engaged by a screw-shaped profile. Roller contact bearing and a housing has been used to lower the friction. The spindles are caused to rotate by the liquid flow which passes in an axial direction through the device. Self-contained part volumes are continuously filled and emptied. No pressure or pulsations are caused by principle of measurement. Two non-contact sensors scan the sensing wheel which is attached to the measuring wheel. A bi-direction flow is possible through two sensors. No deflection is produced by the inflow and outflow. A relatively low pressure drop is exhibited by the device. If measurement is done in this way, then there is no need for the flow to be calmed at the outlet and at the inlet. A measurement medium is used to lubricate all the moving parts.
