Nutating Disc Flow Meter Working Principle, Applications, Advantages and Disadvantages

schematic diagram of nutating disc meter

Read: Positive displacement type flow meter

Design/construction of nutating disc flow meter

Above figure shows the schematic diagram of nutating disc meter. It consists of a precision machined chamber, a center ball, movable disc, and counter mechanism. The disc is integral to the ball/sphere mounted inside the chamber. A small pin is fastened to the ball to convert nutating motion/ eccentric spinning motion of the ball into rotary motion of the shaft. The disc is pivoted at the geometric center, and it is allowed to nutate or wobble in a specially designed chamber. The controlled clearance between the disc and chamber ensures the proper sealing and minimum leakage.

How nutating disc flow meter work

Nutating disc flow meter cross-section animation

The disc divides the chamber into two equal volume.  In above fig, water enters at the left side of the eccentrically mounted disc.  The liquid pressure sets the disc in motion, results in the quantity of liquid that enters left side of the chamber will be rolled out through the outlet. When the disc and ball wobble it generate a cone with the apex at geometric center, this motion is getting translated into a rotary motion of shaft by the pin fastened to the ball. The movement of the disc is then transmitted by the cam and gear train to the totalizer or pulse transmitter. Each complete cycle of nutation of the disc will be counted by the counter mechanism which can be directly calibrated in terms of volume of liquid received or discharged. Each revolution of disc indicates the passage of fixed volume of fluid.

A variety of secondary accessories, which perform additional functions, can be added to this fundamental mechanism. For example, Count resetting device.
Nutating disc engine
Fig shows a Nutating disc engine

Read: Oscillating piston flow meter working, advantages and disadvantages
- Differential Pressure flow meter

Applications of nutating disc flow meter

Nutating disc meter one of the common flow meter, it is used extensively in residential water services measurement, and also it can be used in many industrial applications. It can be used in automatic batching of liquid.

Advantages and Disadvantages of nutating disc flow meter

Advantages
  1. Relatively low cost
  2. Less affected by the velocity profile in downstream and upstream.
  3. The nutating-disc is durable, minimum maintenance.
  4. High accuracy, repeatability. (Accuracy is about ± 1%)
  5. Low-pressure drop.
  6. Eliminate the requirement of straight upstream and downstream piping.
  7. Applicable to automatic liquid batching System
  8. No of materials are available for construction

Disadvantages
  1. Performance may affected by suspended solid particle. (The strain of suitable mesh size is used to avoid this problem)
  2. It is limited to pipe size and capacity.
  3. Only clean fluids can be measured.
  4. Accuracy is affected by the viscosity of fluid flow through them.

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