When a fluid is thick, viscous, or inconsistent — oils, fuels, syrups, and similar liquids — many flow measurement technologies start to struggle. An oval gear flow meter is built specifically for this kind of application, and it’s why positive displacement remains the go-to choice for accurate viscous fluid measurement across oil, fuel, and lubricant handling.

Oval Gear Meter

How an Oval Gear Flow Meter Works

Inside an oval gear meter, two oval-shaped gears rotate together, trapping a precisely known volume of fluid between each gear and the meter housing on every rotation. As the gears turn, that fixed volume is released downstream, and the meter counts rotations to calculate total flow. Because it’s measuring discrete, mechanically trapped volumes rather than inferring flow from velocity, an oval gear meter delivers highly repeatable accuracy — even with fluids that are thick, viscous, or don’t flow in a clean, predictable stream.

Why Positive Displacement Wins for Oil & Fuel

Technologies like turbine or ultrasonic meters rely on reading a flow profile through the fluid, which becomes less reliable as viscosity increases. Oval gear meters sidestep that problem entirely — viscosity actually improves the seal between the gears and housing, which is part of why positive displacement technology performs so consistently well with oils, fuels, and lubricants where other meter types lose accuracy.

There’s a practical installation benefit too: unlike many flow meter technologies, oval gear meters don’t need a long straight run of pipe upstream and downstream to read accurately, since they’re not measuring a velocity profile. That makes them a genuinely easier meter to retrofit into an existing, space-constrained pipe run.

Click on link below for Flomec youtube video
https://www.youtube.com/watch?v=txjaWaNRiLc

BES Flowmeters & the Flomec Range

BES Flowmeters supplies the Flomec oval gear range as part of our broader positive displacement flow meter lineup, purpose-built for oils, fuels, and other viscous industrial liquids. If your application involves a different fluid type or viscosity range, it’s also worth comparing against our wider liquid flow meter range to confirm oval gear is the right fit before you order.

 

Frequently Asked Questions

Why are oval gear meters preferred for oil and fuel measurement?

Oval gear positive displacement meters measure flow by physically trapping and releasing fixed volumes of fluid as a pair of gears rotate, which makes them highly accurate even with thick, viscous fluids like oils and fuels that other flow measurement technologies can struggle to read reliably.

Do oval gear meters need a straight pipe run like other flow meters?

No — this is one of the practical advantages of positive displacement technology. Because the meter is measuring discrete volumes mechanically rather than reading a flow profile, oval gear meters are largely unaffected by upstream turbulence from bends, valves, or fittings.

What viscosity range can an oval gear flow meter handle?

Oval gear meters are well suited to a wide viscosity range, from relatively thin fuels through to thick oils and lubricants, with the specific range depending on the model — our team can confirm the right meter for your fluid’s viscosity and expected flow rate.