Current position > Product detail
『Flow Meter Low Flow: High-Precision Sensors for Miniature and Chemical Injection Lines』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)
```html
Flow Meter Low Flow: High-Precision Sensors for Miniature and Chemical Injection Lines
Quick Answer: For low flow rates below 5 kg/h on 1/8 inch or DN4 lines, Silver Instruments supplies Coriolis mass flow meters with 0.1% accuracy. Thermal mass flow meters cover gas micro flows down to 0.1 mL/min. Both sensor types handle chemical injection in oil & gas and dosing applications with materials like Hastelloy C‑22 and 316L.
Most engineers skip this part, but it matters. A standard DN15 flow meter reads zero when real flow is moving through a chemical injection skid. The sensor needs enough length to generate a signal. In low flow applications, that signal never shows up. We have seen this on a customer site in Oman, where an oval gear meter on a corrosion inhibitor line gave erratic readings because the flow was too intermittent. The real demand is not just a small meter. It is a sensor designed to resolve very small mass or volume movements without a required straight run of 20 pipe diameters.
When a General Purpose Flow Meter Fails at Low Flow
Low flow is not a scaled‑down version of normal flow. A turbine meter rated at 0.5–10 m³/h loses linearity below 0.3 m³/h. A vortex meter loses its shedder bar signal and outputs 4 mA even when fluid moves. For chemical injection, the dose rate might be 2 L/h of methanol on a gas wellhead in Australia. Or 0.6 L/h of antiscalant in a desalination plant in Saudi Arabia. At these rates, the inertia of a rotor or the thermal lag of a basic sensor destroys repeatability. The meter becomes a guess. The process engineer then overdoses chemicals by 15% just to stay safe. That costs money.
Coriolis Mass Flow Meters for Micro Flow Lines
Silver Instruments supplies a dedicated ultra‑low flow Coriolis sensor. It uses a single bent tube with DN1 to DN4 process connections. The tube oscillates at high frequency, detecting mass flow down to 0.4 kg/h with liquids and 0.02 kg/h with gases. Density is measured simultaneously, so the output is real mass, not volume compensated for temperature. We ship these to chemical injection skid builders in Malaysia and to a paint manufacturer in Vietnam. The wetted material is usually 316L stainless, but Hastelloy C‑22 is available for hydrochloric acid injection or ferric chloride dosing in water treatment. The transmitter delivers 4‑20 mA HART, pulse, and RS485 Modbus. The accuracy statement on the calibration certificate reads 0.1% of rate for liquid, not just 0.1% of full scale. That distinction is critical at 1% of the meter’s max flow.
Installation is blind friendly. The sensor arrives with a factory zero at process temperature. The pipe connection is a 1/4 inch compression fitting or a 1/8 inch NPT female thread. No straight pipe runs are required because the Coriolis principle does not depend on flow profile. For offshore chemical injection panels in the North Sea, this means the sensor fits inside a cramped enclosure without special pipe geometry.
Thermal Mass Flow Meters for Gas Micro Flow
On the gas side, thermal mass flow works where Coriolis struggles. A thermal sensor with a capillary bypass measures flow rates from 0.1 mL/min up to 10 L/min of nitrogen, natural gas, or CO2. The constant temperature difference technique gives direct mass flow without pressure and temperature compensation. We have shipped these to biogas analyzer OEMs in Brazil and to an activated carbon manufacturer in South Africa. The sensor is built around a stainless steel flow body with an internal laminar flow element. The electronics package outputs 4‑20 mA, a 0–5 VDC option, and RS485 with Modbus RTU. Response time is under 500 ms, so it catches the peak flow of a pneumatic valve leak test. We spec the accuracy at ±0.5% of reading plus ±0.1% of full scale. Fo
Chemical Injection Metering in Oil & Gas and Process
Chemical injection runs with pulsating diaphragm or plunger pumps. The flow is not steady. A Coriolis meter with fast DSP signal processing reads mass flow 100 times per second. The transmitter averages this and outputs a smooth 4‑20 mA. In a PDO field in Oman, a customer used a Silver Instruments micro Coriolis meter on a scale inhibitor line after a positive displacement pump. The pump stroke created a 3 Hz pressure oscillation. The meter still delivered a totalized mass with 0.15% repeatability over a 24‑hour test. This data feeds the SCADA so the injection rate is proven, not assumed. For methanol injection, the low temperature rating of the sensor goes to –40 °C, which works for Canadian winter wellheads and LNG liquefaction plants.
Materials, Process Connections, and Certifications
Wetted materials are chosen by the chemical. Standard is 316L. For seawater boosted with sodium hypochlorite, we use super duplex or Hastelloy. Process connections include 1/16 inch, 1/8 inch, 1/4 inch compression fittings, NPT threads, and miniature flanges per ANSI B16.5 1/2 inch class 150. The pressure rating is 100 bar on the tube sensor body. Temperature rating is –50 °C to +200 °C. For ATEX Zone 1 environments, the transmitter comes in an explosion‑proof housing with Ex d IIC T6 certification. IECEx is also available for Australian WA oilfields and Middle East projects.
How to Get a Fast Quotation
The quickest path to a price is sending your process data. Tell us the fluid name, the required flow range in kg/h or L/h, the pipe size (DN or inch), the operating pressure in bar, the temperature in °C, and the wetted material preference. Send this to [email protected] or WhatsApp +86‑25‑52155837. Most quotes for standard low flow Coriolis meters go out within 6 hours during our business day.
FAQ
What is the smallest flow a Coriolis meter can measure?
The ultra‑low flow Coriolis sensor from Silver Instruments measures liquid down to 0.4 kg/h and gas down to 0.02 kg/h with a DN1 connection. The tube ID is as small as 0.5 mm to keep fluid velocity high enough for stable oscillation.
Does a micro flow meter need a straight run of pipe?
No straight run required for Coriolis mass flow meters, even at micro flow. The measurement principle is independent of flow profile. For thermal mass meters, a short calming section is built into the sensor, so additional external straight pipe is not needed.
Can I use the same low flow meter for three different chemicals?
You can, but we do not recommend it. Cross‑contamination shifts the calibration and risks corrosion if wetted materials are not matched. Most customers dedicate one sensor per chemical, especially for oxygen scavenger, scale inhibitor, and biocide lines on an injection skid.
What output signals does the micro flow transmitter provide?
Standard is 4‑20 mA HART plus passive pulse or Modbus RS485. The transmitter can power from 24 V DC loop supply. Optionally, there is a 3‑line backlit display showing mass flow rate, total, density, and temperature.
Is the thermal mass flow meter suitable for wet biogas?
Wet gas causes condensation on the sensor elements and leads to drift. If the biogas is dried or water content stays below 5% vol, the thermal meter operates reliably. For saturated biogas, we recommend the Coriolis ultra‑low flow sensor instead.
Get in touch with Silver Automation Instruments.
Email: [email protected]
Tel: +86‑25‑68650347
WhatsApp: +86‑25‑52155837
WeChat: +86 15365082610