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Oval Gear Flow Meter Overview & Advantages

There are numerous choices within the Industrial Flow Meter space these days, with a wide array of design options and enhancements providing for highly accurate, durable and cost effective flow measurement solutions. Since the early 1960’s Positive Displacement Oval Gear Flow Meter technology has provided the design engineer and flow meter market with decades of proven flow measurement advantages. This article was developed to assist the specifier, plant engineering and end-user community with understanding the advantages and limitations of Oval Gear Flow Meter Technology.

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Positive Displacement Oval Gear Measuring Principle

The measuring principle includes two high precision toothed oval gears ( rotors), which are driven by the flow of the media and “mesh” together. In the presence of flow, precise defined volumes of fluid are swept through the meter for each rotor rotation. As the flow increases, so does the rotational speed of the rotors. The number of rotor gear rotations is a measure of the amount of fluid that has passed through the meter – each rotation is detected by a sensor and the volume is calculated using a conversion factor ( K factor ). A key distinction of positive displacement flow meters is they offer direct measurement of the volumetric flow rate.

Fluid Suitability

Oval Gear Flow Meters are built for clean process fluids– solids can be problematic and may wedge between the oval gears. Solids if any, should be soluble and low in concentration.

Good engineering practice always calls for upstream filtration before any mechanical flow meter. Your Oval Gear Flow Meter supplier should be able to recommend correctly sized particulate in line strainers. Air within the liquid stream should be minimized or eliminated upstream of the meter. Gases are not suitable for this flow technology.

Fluids of many types are well suited for Oval Gear Flow Meter consideration – including water.

Design care must be taken when reviewing flow range and meter size considerations, be sure to work with an experienced, high quality Oval Gear manufacturer who can review all details of your flow application.

Oval Gear Flow Meter Advantages

Positive Displacement Oval Gear Flow Meter technology provides for a number of key meter advantages – the right manufacturer can provide:

  • High Accuracy of Reading
  • Excellent Repeatability
  • Minimal Maintenance
  • Suitable for numerous fluids including Water and High Viscous Fluids
  • Ease of Installation, No Flow conditioning
  • Exceptional Turn Down Ratios
  • Accuracy unaffected by changes in Viscosity
  • No power required with pulse or mechanical register
  • Industrial Heavy Duty Robust Design
  • Output options including: Pulse, 4-20mA, Intrinsically Safe & Explosion Proof

Common Oval Gear Fluids:     Common Oval Gear Applications:
Solvents Bio-Diesel / Ethanol Production & Blending
Fuels Fuel Additive Measurement &  Blending
Oils Heating Oil Measurement
Greases Boiler Fuel Measurement
Fuel and Chemical Additives Marine Fuel Measurement
Foam Agents ( Polyols & Isocyanates ) Fuel Measurement Loops – supply & return
Sealants Lubricant blending & dispensing
Emulsions Hydraulic Fluids Measurement
Epoxies & Adhesives Polymer Measurement
Water Test Stand Measurement
DI Water Solvent Manufacturing / Blending
Acids & Bases Polyurethane Manufacturing


Typical Industries:

The OEM process fluid segment has embraced Oval Gear Flow technology due to very small footprint offerings, no flow conditioning – which means you can put the meter in very tight spots, high accuracy and repeatability with very attractive volume unit costs.

Fuel Product and Fuel Additive manufacturers need highly accurate and repeatable blend / batch flow measurement suitable for harsh plant, and mobile environments.

Fuel Measurement, Consumption and Monitoring markets need highly accurate fuel supply and return meters with and without temperature compensation capabilities. Mining, Marine, Boiler, Fracking and other High Fuel Consumption clients need to measure and collect precise fuel burn data in engine, generator and pump feed loops.


Oval Gear Flow Meters can be used in a wide range of media applications and are designed for clean process fluids. No flow conditioning allows for superior design flexibility. Maintenance is minimal and changing viscosities do not affect meter accuracy. Cost of ownership can be very attractive compared to other flow technologies while providing highly accurate and repeatable results. Oval Gear Meters are mechanical meters and should not be used in fluids with non-soluble particulate. This is a liquids only meter – gases are not suitable. Water like applications should always be reviewed by a qualified Oval Gear Flow Meter Manufacturer.

Contact Macnaught USA for all your Americas Macnaught Oval Gear Flow Meter needs.

Macnaught is the largest Oval Gear Flow Meter manufacturer globally. We only make Oval Gear Flow Meter instrument technology and have been since 1964.

Macnaught USA can process Flow Meter quotes within the hour with supporting documentation for USA, Canada, Mexico, Central America, South America and the Caribbean.

Aluminum, Stainless Steel and PPS materials of construction are available.

Pulse / 4-20mA / Intrinsically Safe / Explosion Proof Output options
Integral Display Options with Rate & Total only, or with Display with Pulse and 4-20mA output
Remote Flow Computers with advanced logic & communication protocols available.

We carry a large inventory of stocked meters in sizes ¼” thru 4” with flow ranges as low as .13 Gallons per Hour to 317 Gallons per Minute. Non-stock meters can ship in 5-14 business days. All Flow Meters are tested with an individual calibration certificate along with K-Factor.

Receive an Immediate Flow Meter Proposal or Call our Meter Hotline - (813) 896-2710

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