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High-Sensitivity Flow Meter Low Flow Rate Solutions for Micro-Dosing
Quick Answer: For micro-dosing applications, Coriolis mass flow meters and thermal mass flow meters deliver the best low-flow accuracy. A DN2 or DN4 Coriolis meter can measure flow rates as low as 0.05 kg/h with ±0.2 % reading accuracy. Send us your fluid type, minimum and maximum flow rate, pipe size, and operating pressure for a direct price quotation.
You need to inject a tiny amount of catalyst into a reactor. Or you add a precise dose of vitamin concentrate into a beverage line. The flow rate is sometimes below 1 litre per hour. A standard electromagnetic flow meter cannot detect this. It simply reads zero or drifts. This is where high-sensitivity flow meters designed for micro-dosing solve the problem.
Silver Automation Instruments supplies low flow rate meters that measure as low as 0.01 kg/h. These instruments go into chemical dosing skids, pharmaceutical filling machines, additive injection for food, and pilot plants across Southeast Asia, the Middle East, and Oceania.
Coriolis mass flow meters for micro-dosing
Most engineers choose a Coriolis meter when repeatability matters. Our miniature Coriolis meters come in DN2, DN4, and DN8 sizes. A DN2 sensor tube has a very small internal volume. It reacts to mass flow changes in milliseconds. Accuracy reaches ±0.1 % to ±0.2 % of reading. Repeatability is better than ±0.05 %. You can measure mass flow directly, no need for separate density or temperature compensation.
We have supplied a DN4 Coriolis meter to a paint additive manufacturer in Vietnam. They dose a cobalt-based drier into a 50‑litre batch. Flow range is 0.2–2.0 kg/h. Operating pressure is 6 bar. Fluid viscosity is around 200 cP. The meter outputs 4–20 mA HART to their PLC. Before using our meter, they relied on a peristaltic pump with open-loop control. Now they close the loop and record every milligram of additive.
Thermal mass flow meters for low gas flows
Micro-dosing is not only for liquids. Gas injection into a flare header or a burner often requires very low flow measurement. Thermal mass flow meters excel here. Our insertion thermal mass flow meter can measure air or nitrogen flows from 0.1 Nm³/h upwards. The sensor uses a PT100 reference element and a heated sensor. It measures the cooling effect of gas molecules. This principle works down to almost zero flow.
A water treatment plant in Saudi Arabia uses our thermal mass flow meter to dose chlorine gas at 0.3–1.5 kg/h into a drinking water line. They needed flow confirmation to meet local regulation requirements. The meter provides a 4–20 mA signal and a totalizer pulse. Accuracy is ±2 % of reading in this low range. This is not a laboratory instrument, but it is robust and works in a dusty pump room at 50 °C ambient temperature.
Oval gear flow meters for viscous liquids
Sometimes the fluid is viscous, like silicone oil or glucose syrup. A Coriolis meter may be too expensive for the budget. An oval gear positive displacement meter can be a good alternative. Our miniature oval gear meter with DN4 connections handles 0.5–50 L/h. It works with fluids from 1 cP to over 1000 cP. The gears rotate and each pocket displaces
Last year a customer in Nigeria needed to inject pour point depressant into a crude oil pipeline. Flow range was 2–20 L/h. Fluid viscosity 300 cP at line temperature. Pipe size DN6. They ordered two oval gear meters with local indicators and pulse output. The total cost was less than one small Coriolis, and it worked without recalibration for over 12 months.
Critical installation factors
Low flow measurement is sensitive to installation. Always follow these rules. Keep the meter full of liquid. Avoid air bubbles. Use a back-pressure valve downstream to prevent flashing if the fluid is volatile. Mount a Coriolis meter so the tubes are self-draining only if you need to clean it, otherwise keep it flooded. Thermal mass flow meters need straight run pipe of 10D upstream and 5D downstream, even if the manufacturer says less. In practice, we have seen bends and valves very close to the sensor cause swirl and huge errors at low flow.
Temperature control matters. A change of 5 °C can shift the zero on a thermal mass flow meter. That is why our low-flow thermal meters include an automatic zero-tracking function. You can also select ATEX Zone 1 or Zone 2 certification for hazardous areas. Silver Instruments supplies meters with Ex d or Ex ia protection according to IECEx standards.
Getting a quote from Silver Automation Instruments
Send us an email with your process data. We need fluid name, density or viscosity if known, minimum and maximum flow rate, pipe size, operating pressure, and temperature. Our engineers will select the right meter and sensor size. We will provide a technical data sheet and a commercial offer within one working day. You can reach us at [email protected] or call +86-25-68650347. WhatsApp and WeChat are also available on +86 15365082610.
FAQ
What is the smallest flow rate a Coriolis meter can measure?
A miniature DN2 Coriolis meter can measure down to 0.01 kg/h for liquids with density close to water. For gases, the limit depends on density, but 0.05 kg/h is typical.
Can I use a thermal mass flow meter for liquid micro-dosing?
No. Thermal mass flow meters work only with gases. For liquid micro-dosing, use a Coriolis mass flow meter or an oval gear positive displacement meter.
Do you supply meters with ATEX certification for low flow applications?
Yes. We provide Coriolis, thermal mass, and oval gear meters with ATEX Zone 1 or Zone 2 certification. IECEx is also available on request.
What output signals do your low flow meters provide?
Standard options are 4–20 mA HART, pulse, or RS485 Modbus. We can also supply Foundation Fieldbus or Profibus PA if you need it for a DCS integration.
How do I avoid zero drift on a low-flow Coriolis meter?
Zero drift often comes from stress on the sensor or two-phase flow. Install the meter correctly, avoid pipe strain, and always fill the meter completely with liquid. Run an auto-zero function after installation. If drift persists, contact our service team.