Nutating flow meter basics

instrumentation

#1

Nutating flowmeter is a positive displacement type flowmeter. Other names for these meters are disk or wobble plate meters.

nutating flowmeter

Design & Operation:

nutating flowmeter

The top and bottom surfaces of the measuring chamber are conical, extending inward, and the chamber side-wall is spherical.The movable element is the disk mounted on the central ball, from the top of which a shaft extends that is perpendicular to the disk.

This shaft is held in an inclined position by a cam roller so that the disk is in contact with the chamber bottom along a radial element on one side of the ball and in contact with the top in the same radial plane on the other side of the ball. The disk is prevented from rotating about its own axis by a radial partition.

The inlet and outlet ports are in the side-wall of the case, adjacent to, and on opposite sides of the radial partition. Liquid enters the measuring chamber alternately above and below the disk and passes around the conical measuring chamber to the outlet port.

This movement of the liquid around the measuring chamber, first above, and then below the disk, imparts a nutating motion to the disk. As the disk nutates, the top of the shaft moves in a circular path and, by engaging a crank, operates the meter register.

Advantages:

  • Low cost, Because of the simplicity of its construction

  • Simple and rugged construction

  • High accuracy

  • Widely used as a domestic water meter