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Metrys The Metrys wordmark, set in a high-contrast swash serif.
A Metrys oval-gear flow meter with a dark flanged body marked with IN and OUT arrows and a turquoise LCD head on a stainless stem, shown beside a pair of its toothed oval rotors.
Oval-gear flow meter, drawn illustration

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A Metrys oval-gear flow meter with a dark flanged body marked with IN and OUT arrows and a turquoise LCD head on a stainless stem, shown beside a pair of its toothed oval rotors.
Oval-gear flow meter, drawn illustration

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Flow meters OG-200

Oval-Gear Flow Meter

A positive-displacement meter for oils and viscous liquids, DN3 to DN200.

Pipe size range
DN3 to DN200
Accuracy
±0.5%
Transmitter mounting
Integral or remote
Power supply
5–24 V DC or battery

Documents

Download datasheet (Opens in a new tab)

Overview

Why buyers choose it

  • Counts volume, not velocity

    A fixed pocket per turn, which is why it is the meter used where somebody pays per litre.

  • Viscosity helps it

    A thick oil seals the gears better. The liquid a turbine meter gets wrong is the one this gets right.

  • From DN3, at 50 bar

    Small enough for a dispensing nozzle and rated for the pressure a fuel skid runs at.

  • The O-ring is the spec

    NBR or Viton, chosen for the fluid. The wrong elastomer in a solvent is the usual failure.

In detail

An oval-gear meter counts volume directly. Two meshing gears trap a fixed pocket of liquid each turn and pass it downstream, so the count is a measurement of volume rather than an inference from velocity. That makes it the honest answer for custody transfer of oil, where somebody is paying per litre.

Viscosity works in its favour, which is the opposite of the turbine, vortex and ultrasonic principles. A thick oil seals the gear clearances better and reduces slip, so the meter that struggles with thin solvents is at its best on heavy fuel oil and lubricants — exactly the liquids a turbine meter mismeasures.

It reaches DN3, and fifty bar, and up to 80 °C. Bodies are aluminium, SS304 or SS316, with NBR or Viton O-rings chosen for the fluid: the wrong elastomer in a solvent is the usual reason one of these fails, and it is a five-rupee part.

It runs from 5 to 24 V DC or a battery, so a dispensing point does not need mains at the nozzle, and it is offered flameproof for fuel areas.

Technical specifications

Metrological

Measuring principle Positive displacement, oval gear
Accuracy ±0.5%
Repeatability ±0.1% of span

Hydraulic

Measured media Diesel, kerosene, petrol, light and heavy oils, food and lubrication oils, solvents, chemicals, clear water
Medium temperature Up to 80 °C
Maximum working pressure Up to 50 bar

Materials

Body material Aluminium, SS304 or SS316
Rotor material Aluminium, SS316 or PPS; shaft SS316; O-rings NBR or Viton
Enclosure material Aluminium or plastic

Electrical

Power supply 5–24 V DC or battery
Outputs 4–20 mA, NPN pulse and relay
Display LCD in engineering units

Communication

Communication RS485, GSM/GPRS or LoRa/NB-IoT

Environmental

Protection class IP65, IP67 or IP68
Explosion protection Flameproof (FLP)
Ambient conditions −20 to +60 °C, 5% to 85% humidity

Dimensions and installation

Schematic, not to scale
Pipe size range DN3 to DN200
End connection Threaded, flanged or tri-clover
Transmitter mounting Integral or remote

Parts

Parts of an oval-gear meter

How a meter of this type is built, and what this model is made of.

Parts of an oval-gear meter, drawn illustration Exploded illustration of an oval-gear flow meter's parts, numbered top to bottom: 1 register with display, 2 cover, 3 magnetic coupling, 4 drive oval gear, 5 driven oval gear, 6 body, 7 flange. 1 2 3 4 5 6 7
Illustrative: how a meter of this type is built. This model's own materials and figures are in the table and its specifications.

  1. Register with display

    Totalises the gear rotations and shows the volume passed.

    Display LCD in engineering units

  2. Cover

    Closes the gear chamber and carries the register.

  3. Magnetic coupling

    Carries the gear rotation across the sealed chamber wall to the register without a shaft seal.

  4. Drive oval gear

    Rotates as trapped liquid pushes it, driving the second gear.

    Rotor material Aluminium, SS316 or PPS; shaft SS316; O-rings NBR or Viton

  5. Driven oval gear

    Meshes with the drive gear and completes each measured pocket of liquid.

    Rotor material Aluminium, SS316 or PPS; shaft SS316; O-rings NBR or Viton

  6. Body

    Forms the measuring chamber the gears trap liquid in.

    Body material Aluminium, SS304 or SS316

  7. Flange

    Bolts the meter to the pipeline.

    End connection Threaded, flanged or tri-clover

Download centre

Everything you need to specify.

Documents for the Oval-Gear Flow Meter.

Approvals and certificates

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