Working principle diagram of the oval gear flow meter

Working Principle Diagram of Oval Gear Flow Meter‌

The oval gear flow meter operates based on positive displacement measurement, where two intermeshing elliptical gears rotate within a precisely machined chamber to quantify fluid volume.

Key Operational Stages‌

Initial Position (Fig. a)‌

The upper gear (A) acts as the driving rotor under inlet pressure (P₁), expelling the trapped fluid from its crescent-shaped chamber.

The lower gear (B) remains passive, meshing with gear A to maintain sealing.

Intermediate Position (Fig. b)‌

Both gears become active rotors, transitioning under combined pressure differential forces.

Final Position (Fig. c)‌

Gear B now drives the rotation, discharging its chamber volume while gear A resets.

Each full rotation displaces ‌4× the crescent volume‌ (V₀), calculated as:

𝑄

=

4

𝑛

𝑉

0

Q=4nV

0

where n = rotational frequency (r/s).

Critical Design Features‌

Material Options‌: Stainless steel (316L/304), cast steel, or cast iron for compatibility with corrosive/oily fluids.

Accuracy‌: ±0.2%–1% depending on calibration, unaffected by viscosity changes.

Mounting‌: Requires upstream filtration to prevent gear damage from particulates.

Applications‌

High-viscosity fluids‌: Heavy oils, resins, and polymer solutions.

Fuel systems‌: Diesel, biodiesel, and kerosene metering.

Note: Diagrams illustrate gear rotation phases and volumetric displacement mechanics.