Helical Rotor Positive Displacement Meter
Two highly accurate cycloid-shaped screw spindles mesh and rotate inside a cylindrical housing with two overlapping holes in the form of a figure 8, which forms the measuring chamber. Liquid flows in axial direction and rotates the spindles; it is forced along the measuring chamber bores by the profile of the spindles. This occurs without pulsation and with minimum leakage. An inductive pickoff will detect the speed of the spindle pair through the housing via a pole wheel with a high number of gears. The speed of the spindles is directly proportional to the volumetric flow rate over a very wide range. This sensor will output a highly accurate pulse train or an analog 4-20 mA signal when used in conjunction with the ALVTM local display unit. All units come factory calibrated under conditions that match the end user's operating viscosity as closely as possible in order to determine the optimal K-factor (pulses per unit volume).