An oval gear flow meter is a positive displacement meter built for accurate, repeatable measurement of clean liquids — from diesel, oils and lubricants to solvents, alcohols and mildly aggressive chemicals. With only two moving parts, these meters are compact, durable and simple to maintain, making them a reliable choice for fuel dispensing, chemical dosing, lubrication systems and batch metering across Australian industry.
How an Oval Gear Flow Meter Works
Inside the measuring chamber, two precision oval gears mesh together and rotate as liquid flows through the meter. With each revolution, the gears trap and discharge a fixed volume of liquid between the gear and the chamber wall. Counting those revolutions — mechanically through a register, or electronically through a pulse sensor — gives a direct measurement of the volume that has passed through.
Because the meter measures volume directly, it does not rely on a settled flow profile, so long straight pipe runs before and after the meter are not required. Thicker liquids also reduce internal slippage, which is why oval gear meters hold their accuracy across a wide range of viscosities where turbine flow meters are better suited to thin, low-viscosity liquids.
Why Choose an Oval Gear Meter?
- High accuracy: typically ±0.5% of reading, with excellent repeatability of ±0.1%.
- Handles viscous liquids: standard meters accurately measure products up to 1,000 cP.
- Two moving parts: low wear, long service life and straightforward maintenance.
- Flexible displays and outputs: mechanical registers, digital displays, pulse outputs and batch controllers.
- Easy installation: no flow conditioning or long straight runs needed.
Our Oval Gear Flow Meter Range
Flomec OM Series — Available in small, medium and large capacity models. Medium capacity Flomec OM meters cover flow rates from 1.0 to 450 L/min, with stainless steel or aluminium bodies and stainless steel or PPS rotors. Options include mechanical displays, digital rate and total displays, the EB11 batch controller, and a dedicated OM chemical flow meter.
Macnaught M-Series — Macnaught’s original oval gear design, offered across a wide selection of flow rates and suited to a broad range of fluid viscosities. The 1″ M-Series HD mechanical meter handles flows between 6 and 120 L/min and features a square display with reset knob.
Macnaught MX-Series — Robust MX-Series meters offer interchangeable pulse outputs and direct-mount digital displays, with pressure ratings up to 2,000 psi. Pair them with the Macnaught ERB batching register for precise batch control.
Common Applications
- Diesel and fuel and oil dispensing
- Lubricant distribution in workshops and fleet depots
- Chemical and solvent dosing and transfer
- Batch filling and blending
- Alcohols and other clean industrial liquids
Oval Gear Flow Meter FAQs
How does an oval gear flow meter work?
Two oval gears rotate inside a measuring chamber as liquid passes through, discharging a fixed volume with every revolution. The meter counts the revolutions to calculate the total volume.
Is an oval gear meter a positive displacement meter?
Yes. The oval gear meter is one of the most common types of positive displacement flow meters, measuring liquid in fixed, repeatable volumes.
Oval gear or turbine flow meter — which should I choose?
Oval gear meters are the better choice for oils, fuels and viscous liquids. Turbine meters suit thin, low-viscosity liquids such as water. If you’re unsure, our team can recommend the right meter for your liquid and flow rate.
Do oval gear meters need a strainer?
Oval gear meters are designed for clean liquids, so fitting a strainer upstream is recommended to protect the gears from debris and keep readings accurate.
The Oval Gear Meter Experts
Established in 1986, BES Flowmeters supplies flow measurement solutions to industry right across Australia. As an authorised distributor for Flomec and Macnaught, our team can help you choose the right size, body material, rotor and display for your liquid, flow rate and viscosity. Call (03) 5956 8685 or request a quote today.
