Oval Gear Flow Meters & Oval Gear Flow Sensors: Precision Volumetric Systems for Paints and Oils

Quick Answer: Oval gear flow meters are positive displacement instruments. They measure paints, oils, varnishes, and other viscous liquids with high repeatability at low flow rates. For most paint and oil processes, select a DN15 to DN80 meter with FKM or PTFE seals and pulse or 4-20 mA HART output.

Why Oval Gear Meters Fit Paint and Oil Batching

Here is the thing. Paint and oil flows are thicker than water and they can change viscosity with temperature. A turbine meter often struggles in these conditions. Oval gear flow meters do not rely on conductivity or high velocity. Two oval gears rotate inside a precision chamber. Each rotation moves a fixed volume from inlet to outlet.

Volumetric measurement is what paint batching and oil dosing need. A DN25 oval gear meter can measure 1 to 20 litres per minute with reading accuracy near plus or minus 0.5 percent. Repeatability usually lands near plus or minus 0.1 percent. In one paint plant in Vietnam, a 25 mm cast iron meter handled alkyd resin at 3,200 cP. The operator sent a 4-20 mA HART signal to the PLC and used pulse output for batch total. That setup replaced manual weighing and cut batch time by about 12 minutes per shift.

Selecting the Right Meter for Paints and Oils

Start with pipe size and flow range. DN15 suits 0.5 to 5 litres per minute. DN25 covers 1 to 20. DN40 covers 5 to 100. DN50 covers 10 to 200. DN80 covers 25 to 500 litres per minute. These ranges change with viscosity and back pressure. Send us your pressure (bar), temperature (°C), pipe size (DN), and flow range.

Material selection matters. Cast iron with FKM seals works for many solvent based paints and mineral oils. Stainless steel 316 body with PTFE or PEEK gears suits water based paints, inks, and aggressive solvents. Food grade paints and edible oils may need stainless steel with EPDM seals. Always check seal compatibility with ketones, esters, and aromatic solvents.

Temperature is another factor. Standard oval gear meters handle -20 to 120 °C. For hot oil or reactor discharge, specify PT100 temperature compensation and a high temperature gear set. Silver Automation Instruments offers PT100 integration on most DN15 to DN100 oval gear flow sensors.

Signal Output and Process Integration

Most engineers choose pulse output for simple batch controllers. Each pulse represents a fixed volume. The PLC counts pulses and converts them to total volume. For continuous paint mixing or oil blending, 4-20 mA HART gives flow rate. Some sites add Modbus RTU over RS485 for direct connection to a DCS or SCADA system.

We have seen this on customer sites many times. An oil blending plant in the United Arab Emirates runs four DN40 oval gear meters on one manifold. Each meter sends 4-20 mA HART to a flow computer. The pulse output runs a local batch controller. The plant fills IBC tanks with hydraulic oil and gear oil. Because the meter is positive displacement, flow pulsation does not cause false totals.

For hazardous areas, Silver Automation Instruments can supply oval gear meters with ATEX Zone 1 approval. Specify the gas group and temperature class with your inquiry.

Installation Tips That Prevent Meter Failure

Most oval gear meter problems come from dirt, air, or wrong pipe connection. Install a Y strainer or basket filter upstream. A 100 mesh strainer is common for paints. For heavy oils, use a 60 mesh strainer to avoid high pressure drop. Dirt or dried paint particles can jam the oval gears.

Air pockets cause the rotors to spin without moving liquid. That creates false counts. Mount the meter so liquid stays inside the measuring chamber. A back pressure valve downstream helps keep the chamber full with low viscosity oils and solvents. In practice, 0.5 to 1.5 bar of back pressure is enough for many thin fluids.

Do not use an oval gear meter on a suction line. Install it on the discharge side of the pump. The meter does not need long straight pipe like an electromagnetic flow meter, but turbulence from a partially open ball valve can affect accuracy.

Common Paint and Oil Applications

Silver Automation Instruments oval gear flow sensors work in solvent based paint filling, ink dosing, diesel and fuel oil transfer, hydraulic oil blending, edible oil batching, and marine fuel measurement. A customer in the Philippines uses a DN50 stainless steel oval gear meter for coconut oil transfer at 40 °C. A customer in Nigeria uses a DN25 cast iron meter for diesel generator fuel consumption monitoring. A customer in Chile uses a DN15 meter for varnish dosing into small cans.

These meters are mechanical and robust. They suit small and medium plants without advanced flow calibration labs. The main spare parts are gears, bearings, and seals. Keep a spare gear set and seal kit on the shelf to reduce downtime.

Pricing and Request for Quotation

Price depends on size, body material, seal material, and output type. We do not publish fixed online prices because application conditions change the quote. Send us your pressure (bar), temperature (°C), pipe size (DN), and flow range. You can also describe the paint resin, oil grade, or solvent name so we check material compatibility.

Contact Silver Automation Instruments by phone at +86-25-68650347 or WhatsApp at +86-25-52155837. WeChat is available at +86 15365082610. We respond to most sizing questions within one business day.

FAQ

Can an oval gear flow meter measure water based paint and solvent based paint?
Yes. Select stainless steel 316 body with PTFE or PEEK gears for water based systems. For solvent based systems, check seal compatibility with the solvent blend. FKM seals are common for mineral spirits and many hydrocarbons.

What output signal is best for paint filling machines?
Pulse output is often best for filling machines. Each pulse represents a fixed volume. The PLC counts pulses and closes a valve at the target fill volume. For flow rate monitoring, add 4-20 mA HART or Modbus RTU.

What is the accuracy of an oval gear flow meter for viscous oil?
Reading accuracy can reach plus or minus 0.5 percent for oil viscosity from 5 cP to over 100,000 cP. Repeatability is better, often plus or minus 0.1 percent. Exact accuracy depends on viscosity, back pressure, filtration, and meter size.

Can I install an oval gear flow meter in an ATEX Zone 1 area?
Yes. Silver Automation Instruments offers ATEX Zone 1 oval gear flow meter versions for paint and oil environments. Specify gas group, temperature class, and whether the output should be intrinsically safe or explosion proof.

How do I size a meter for diesel fuel oil with viscosity of 8 cP?
For diesel at 8 cP, a DN15 or DN25 oval gear meter handles many fuel transfer and consumption tasks. Provide the minimum and maximum flow rate in litres per minute. We check rotor speed and pressure drop. Then we recommend the material and output type.

Silver Automation Instruments supplies oval gear flow meters and oval gear flow sensors for paint, ink, oil, fuel, and food grade liquid batching. Ask for a quote with your process data to get a fixed price and delivery schedule.

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