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Quick Answer: Volumetric meters track liquid flow by counting fixed volume chambers inside the meter body. They fit diesel, fuel oil, chemicals, and viscous food grade liquids from DN15 to DN100. Silver Automation Instruments can quote a meter once you send viscosity in cP, pipe size in DN, flow range in L/h, and operating temperature in °C.
A positive displacement meter traps liquid in a known chamber and moves that volume downstream. Each rotation of an oval gear or piston equals a fixed volume. That is different from electromagnetic or ultrasonic meters because the meter body itself segments the flow. The result is a direct mechanical count. There is no flow profile assumption and no minimum conductivity requirement. A volumetric meter does not need the fluid to have a minimum conductivity in µS/cm, unlike an electromagnetic meter.
In practice, this matters for batch dosing and custody transfer. A chemical blender in Malaysia needed repeatable 50 liter batches of epoxy resin at 800 cP. The oval gear meter held a 0.5 percent repeatability over 14 months with one cleaning cycle.
Engineers choose volumetric meters for clean liquids with low to medium flow rates and viscosity from about 1 cP to 2000 cP. Diesel bowsers, marine fuel transfer, paint mixing, edible oil batching, bitumen cutback, and solvent dosing fit this profile. They are not ideal for dirty water with sand or for abrasive slurry because the rotating parts need clearance.
Here is the thing. Many flow meter types lose accuracy when viscosity changes. A volumetric meter keeps the chamber volume fixed, so viscosity shifts from 5 cP to 500 cP do not change the internal displacement. The leak rate changes slightly, but a well built oval gear meter holds accuracy in that range better than a turbine meter.
Silver Instruments focuses on oval gear meters for fuels and chemicals. We also supply gear meters, rotary piston meters, and nutating disc meters for special cases. The oval gear design is common for diesel, biodiesel, light fuel oil, and medium viscosity hydrocarbons. Rotary piston handles higher viscosity pastes and syrups. Nutating disc covers water and light chemicals with lower cost.
For diesel from DN15 to DN50 at 2 to 200 L/min, select the Silver Instruments OGM-D series oval gear meter with an aluminum body and 4-20 mA HART output. For methanol or solvent dosing, stainless steel internals avoid corrosion. For palm oil at 60 °C, use a cast iron or stainless steel body with hardened gears and an accuracy of 0.5 percent or better.
Most volumetric meters from Silver Instruments accept a local mechanical totalizer. That direct counter helps operators verify batch volume without a PLC. For remote monitoring, the meter can include a reed switch pulse output, open collector pulse, 4-20 mA HART, or Modbus. A pulse output works well for batch controllers. A 4-20 mA HART signal suits DCS and flow computers. A PT100 option supports temperature correction for fuel volume at changing diesel temperatures.
One customer in Vietnam ordered 12 oval gear meters for diesel generators at a port. They wanted 4-20 mA HART output plus local totalizer. The installation used a 200 mesh Y strainer upstream. The meters run at 0.8 to 2.4 m³/h per generator and send data to a central fuel monitoring panel.
Send us the fluid type, flow range, viscosity in cP, pressure in bar, temperature in °C, and pipe size DN. That data lets us select body material, seal material, bearing type, and output. Standard ranges cover DN15 to DN100, pressure ratings PN16 to PN40 or Class 150 to 300, temperature from -20 °C to 150 °C, and accuracy from 0.2 percent to 0.5 percent depending on model. Viscosity limits depend on bearing load and clearance class. If you need mass flow in kg/h, we can pair the meter with a density input or offer a Coriolis mass flow meter.
For hazardous area fuel depots, ATEX Zone 1 rated pulse outputs are available. For food grade edible oil, the OGM-S series in stainless steel with PTFE seals and food grade bearings is a standard choice. For marine fuel transfer, include a deaerator or air eliminator because entrained air inflates the count. That is a common mistake on bunker barges.
Most engineers skip this part until a meter reads high. Air in the liquid displaces the chamber and the meter counts air as volume. Install an air eliminator upstream for diesel transfer from day tanks. Second, install a strainer. A 100 to 200 mesh strainer protects the gears from weld slag, rust, and small particles. Third, do not oversize the meter. Running a DN50 oval gear meter at 2 percent of full range increases slip and worsens low flow accuracy. Pick a meter with your normal flow at 30 to 70 percent of full scale.
Volumetric meter price depends on body size, material, wetted parts, and output type. An aluminum oval gear meter for diesel in DN15 costs less than a stainless steel food grade version in DN50. Pulse only versions are lower cost than 4-20 mA HART with local totalizer. Because freight and import duty vary in Southeast Asia, the Middle East, and Latin America, we quote FOB or CIF based on your port and order quantity.
For a fast selection, send Silver Instruments the following data:
Fluid name and viscosity in cP
Flow range in L/h or m³/h
Pipe size in DN
Pressure in bar and temperature in °C
Output type: pulse, 4-20 mA HART, or Modbus
Hazardous area zone if required
Small bubbles cause over registration because the meter counts volume including air. Use an air eliminator or maintain adequate back pressure on the meter outlet.
The standard accuracy is 0.5 percent of reading for medium viscosity liquids. Some calibration runs reach 0.2 percent over a limited range. Repeatability is often 0.05 percent or better, which helps batch dosing.
Yes, if the water is clean and low flow. For dirty water or wastewater, use an electromagnetic flow meter instead. Volumetric meters with aluminum bodies are not suitable for potable water due to corrosion risk.
Clean the strainer every month in dirty systems. Inspect gears every 12 to 24 months depending on fluid. Replace seals and bearings during scheduled calibration. Avoid dry running because gears can seize.
A pulse output connected to a batch controller is simple and reliable. If the site uses a DCS or flow computer, select 4-20 mA HART. We can supply both with a local mechanical totalizer.
Contact Silver Automation Instruments for a volumetric meter quote. Send fluid viscosity in cP, pipe size DN, flow range in L/h, pressure in bar, temperature in °C, and output type to Whatsapp +86-25-52155837 or call +86-25-68650347. We will reply with a recommended model, lead time, and price. WeChat: +86 15365082610. Website: flow-meter.com.au
