Why are oval gear flow meters ideal for high-viscosity fluids?

Oval gear meters are classic positive displacement devices: two oval gears driven by differential pressure rotate and displace a fixed volume per revolution. Accuracy correlates with lubricity and is only weakly affected by viscosity — higher viscosity means less slip and better accuracy, which makes them ideal for diesel, heavy fuel oil, crude oil and resins.

Typical accuracy ±0.2%R~±0.5%R; widely used for marine bunkering, depot loading and chemical batching.