— A Practical Guide for Engineers, EPCs, and Project Teams
In the world of flow measurement, most technologies infer mass flow indirectly—by measuring volumetric flow and then applying density corrections. Coriolis flowmeters are different. They measure mass flow directly, with an accuracy and turndown that no other flow technology can match. This direct measurement capability, combined with the ability to simultaneously measure density and temperature, has made Coriolis meters the gold standard for custody transfer, chemical dosing, and any application where product quality and financial accuracy are paramount.
Yet Coriolis meters are not a universal solution. They are more expensive than volumetric meters, sensitive to installation conditions, and limited in size for large pipelines. Selecting the right Coriolis meter requires a clear understanding of the technology's strengths, limitations, and application-specific requirements.
This guide explains how Coriolis flowmeters work, what makes them accurate, and how to select and install them for industrial process applications.
1. How Coriolis Flowmeters Work
The Coriolis flowmeter operates on the Coriolis effect—a phenomenon that causes a moving mass to experience a force perpendicular to its direction of motion when it is subjected to angular rotation.
1.1 The Vibrating Tube Principle
A Coriolis flowmeter consists of one or two curved or straight tubes through which the fluid flows. An electromagnetic driver vibrates the tube(s) at their natural frequency. When fluid flows through the vibrating tube, the Coriolis force causes a phase shift between the inlet and outlet sides of the tube. This phase shift is directly proportional to the mass flow rate.
Key components:
| Component | Function |
|---|---|
| Flow tubes | Vibrate at natural frequency; carry the process fluid |
| Driver | Electromagnetic coil that maintains tube vibration |
| Sensors (pick-offs) | Detect the phase shift between inlet and outlet |
| Temperature sensor | Measures tube temperature for compensation |
| Signal processing electronics | Converts phase shift into mass flow, density, and temperature outputs |
1.2 Direct Mass Flow Measurement
Because the Coriolis force is generated by the mass of the moving fluid, the meter measures mass flow directly—no density compensation is required. This is the fundamental advantage of Coriolis technology.
Multi-variable output: A single Coriolis meter can simultaneously output:
Mass flow rate (kg/h, lb/min, etc.)
Volumetric flow rate (m³/h, L/min) — calculated from mass flow and density
Density (kg/m³, °API, °Brix)
Temperature (°C, °F)
Concentration (derived from density for binary mixtures)
This multi-variable capability eliminates the need for separate density and temperature transmitters in many applications.
2. Advantages and Limitations
2.1 Advantages
| Advantage | Why It Matters |
|---|---|
| Direct mass flow measurement | No density compensation required; highest accuracy for mass balance and custody transfer |
| Highest accuracy | Up to ±0.05% of mass flow for custody transfer; ±0.1–0.2% for general process |
| Wide turndown | Up to 100:1 or higher; accurate at low flow |
| Multi-variable output | Mass flow, density, temperature, and concentration from one device |
| No moving parts | No wear; minimal maintenance; long service life |
| No upstream/downstream straight pipe | Not sensitive to velocity profile; simpler installation |
| Handles viscous fluids | Not affected by viscosity changes; suitable for heavy oils and slurries |
| Bidirectional measurement | Measures flow in both directions with equal accuracy |
| High pressure capability | Available for pressures up to 1,000 bar or higher |
2.2 Limitations
| Limitation | Impact |
|---|---|
| Higher cost | More expensive than volumetric meters (magnetic, vortex, ultrasonic) |
| Limited size range | Typically up to DN300 (12 inch); larger sizes available but very expensive |
| Pressure drop | The vibrating tubes create some pressure drop—higher than magnetic or ultrasonic |
| Sensitive to vibration | External vibration can affect measurement; requires isolation |
| Sensitive to entrained gas | Gas bubbles cause significant measurement error; may require air elimination |
| Sensitive to two-phase flow | Slug flow or liquid-gas mixtures cause errors and may damage the tubes |
| Zero stability | Requires periodic zeroing; affected by temperature and pressure changes |
| Slurry abrasion | Abrasive slurries can wear the tubes over time; requires special materials |
3. Types of Coriolis Flowmeters
Coriolis flowmeters are available in several tube geometries, each with distinct characteristics.
| Type | Characteristics | Best For |
|---|---|---|
| Curved Tube (U-shape, Delta) | Most common; handles high flow; moderate pressure drop; good accuracy | General process, custody transfer |
| Straight Tube | Lower pressure drop; easier to drain; can be cleaned with pigs; lower accuracy | Hygienic, food, pharmaceutical |
| Single Tube | Compact; lower cost; limited flow range | Small flow rates, chemical dosing |
| Dual Tube | Most common; balanced; higher flow capacity; better accuracy | General process, custody transfer |
| Micro-Bend | Compact; low pressure drop; good for low flow | Chemical dosing, R&D |
Selection principle: For most industrial applications, a dual-tube, curved design provides the best balance of accuracy, capacity, and pressure drop. For hygienic or high-viscosity applications, a straight-tube design may be preferred.
4. Selection Criteria
4.1 Fluid Properties
| Property | Consideration |
|---|---|
| Fluid type | Liquid, gas, or slurry? Coriolis works best with liquids and dense gases |
| Density | Density affects the meter's sensitivity and the need for density compensation |
| Viscosity | High viscosity increases pressure drop but does not affect accuracy |
| Corrosiveness | Determines tube material (316L SS, Hastelloy, Titanium) |
| Abrasiveness | Determines tube material and wall thickness |
| Entrained gas | Gas bubbles cause errors; may require air elimination |
| Temperature | Determines tube material and electronics rating |
4.2 Flow Range and Sizing
The Coriolis meter must be sized to handle the full flow range—from minimum to maximum.
| Parameter | Recommendation |
|---|---|
| Normal flow rate | Should fall within 50–80% of the meter's maximum capacity |
| Minimum flow rate | Must be above the meter's minimum measurable flow |
| Maximum flow rate | Must be below the meter's maximum capacity |
| Turndown required | Ratio of maximum to minimum flow; Coriolis typically achieves 100:1 |
Sizing principle: Select the smallest meter that can handle the maximum flow rate. A smaller meter provides better accuracy at low flow and lower cost. However, be careful not to oversize—a meter that is too large will have poor low-flow accuracy and may not reach its stated turndown.
4.3 Pressure and Temperature
| Parameter | Consideration |
|---|---|
| Maximum operating pressure | Determines tube wall thickness and flange rating |
| Maximum operating temperature | Determines tube material and electronics rating |
| Pressure drop | Coriolis meters create some pressure drop; verify it is acceptable |
| Temperature effects | Zero stability and accuracy are affected by temperature; choose a meter with good temperature compensation |
4.4 Materials
| Component | Material Options |
|---|---|
| Flow tubes | 316L SS, Hastelloy C-276, Titanium, Zirconium |
| Housing | Carbon steel, 316L SS, Hastelloy |
| Flanges | Carbon steel, 316L SS, Hastelloy |
Selection principle: Match tube material to the process fluid. For corrosive fluids, Hastelloy or Titanium may be required. For abrasive slurries, consider a straight-tube design with thicker walls.
4.5 Accuracy and Turndown
| Application | Typical Accuracy | Turndown |
|---|---|---|
| Custody transfer | ±0.05% to ±0.1% | 100:1 |
| Process control | ±0.1% to ±0.2% | 100:1 |
| General monitoring | ±0.2% to ±0.5% | 50:1 to 100:1 |
Accuracy specification basis: Coriolis accuracy is typically specified as % of mass flow rate—not % of full scale. This means a meter with ±0.1% accuracy maintains that accuracy across its entire flow range, not just at full scale.
4.6 Output and Communication
| Output Type | Application |
|---|---|
| 4–20 mA | Mass flow, density, temperature (multiple outputs) |
| 4–20 mA + HART | Digital communication + analog |
| Pulse / Frequency | Totalisation and batch control |
| RS-485 / Modbus | Digital communication for SCADA |
| Profibus PA / Foundation Fieldbus | Fieldbus integration for large systems |
4.7 Certifications
| Certification | Application |
|---|---|
| Ex d / Ex ia | Hazardous areas |
| SIL 2 / SIL 3 | Safety instrumented systems |
| 3A / EHEDG | Food and pharmaceutical |
| OIML R117 | Custody transfer |
| API MPMS | Petroleum measurement |
| ISO 17025 | Calibration traceability |
5. Installation Requirements
5.1 Orientation
| Orientation | Best For | Considerations |
|---|---|---|
| Horizontal | General purpose | Tubes should be oriented to allow drainage; avoid gas pockets |
| Vertical (upward flow) | Slurries, low-velocity fluids | Ensures full pipe; prevents solids settling |
| Vertical (downward flow) | Clean fluids | Avoid for slurries; solids may settle |
Best practice: Install with the tubes oriented to allow complete drainage. For horizontal installation, orient the tubes so that gas bubbles can rise and escape.
5.2 Straight Pipe Requirements
Coriolis meters are not sensitive to velocity profile and do not require straight pipe runs upstream or downstream. However, they should be installed away from pumps, valves, and other vibration sources.
5.3 Vibration Isolation
Coriolis meters are sensitive to external vibration. The vibrating tubes can be affected by vibration from pumps, compressors, and other equipment.
Best practices:
Install the meter on a separate support, isolated from the pipe
Use flexible pipe connections or expansion joints to isolate the meter from pipe vibration
Avoid mounting on vibrating structures
Verify that the meter's natural frequency is well above the process vibration frequency
5.4 Zeroing
Coriolis meters must be zeroed after installation and before commissioning. The zeroing procedure involves:
Ensuring the meter is completely full of fluid
Closing the isolation valves upstream and downstream
Confirming no flow through the meter
Running the zeroing routine from the transmitter or DCS
Best practice: Re-zero the meter after any significant process temperature change, and periodically during operation.
5.5 Entrained Gas
Gas bubbles in the process fluid can cause significant measurement errors. For applications where entrained gas is possible:
Install an air eliminator upstream of the meter
Use a meter with two-phase flow capability (some advanced models can detect and compensate for gas)
Mount the meter in a location where gas can escape
5.6 Grounding
Proper grounding is essential for reliable measurement:
Ground the meter independently
Use shielded cables for signal and power
Follow the manufacturer's grounding recommendations
6. Applications
Coriolis flowmeters are used in a wide range of industries and applications where accuracy and multi-variable measurement are important.
| Industry | Applications |
|---|---|
| Oil & gas | Crude oil custody transfer, natural gas liquids, LPG, refined products |
| Chemical | Chemical dosing, reactant feed, product blending, acid and alkali measurement |
| Food & beverage | Milk, yogurt, juices, syrups, beer, wine, edible oils |
| Pharmaceutical | Drug solutions, buffers, solvents, clean-in-place (CIP) |
| Automotive | Fuel injection testing, paint mixing, coolant flow |
| Marine | Bunkering, fuel oil measurement, ballast water |
| Power | Fuel oil, turbine oil, cooling water, chemical dosing |
| Water & wastewater | Chemical dosing, polymer make-up, sludge measurement |
Custody transfer: Coriolis meters are the preferred technology for custody transfer of high-value fluids—crude oil, refined products, LPG, and chemicals—because their direct mass measurement eliminates the uncertainty of density compensation and volumetric conversion.
7. Common Mistakes to Avoid
| Mistake | Consequence | Prevention |
|---|---|---|
| Sizing by pipe size, not flow range | Poor accuracy at low flow; inadequate turndown | Size by flow range; select smallest meter that handles maximum flow |
| Ignoring pressure drop | Process cannot achieve required flow | Calculate pressure drop; verify pump capacity |
| Installing on vibrating structure | Signal noise; measurement error | Isolate from vibration; use flexible connections |
| No air elimination for gas entrainment | Large measurement errors | Install air eliminator; consider two-phase capable meter |
| No zeroing after installation | Zero offset; systematic error | Zero the meter after installation and after temperature changes |
| Using a standard meter for abrasive slurries | Tube wear; premature failure | Use abrasion-resistant materials; consider straight-tube design |
| Ignoring temperature effects | Zero drift; accuracy degradation | Choose meter with good temperature compensation; re-zero after temperature changes |
| Not verifying custody transfer certification | Meter may not meet regulatory requirements | Verify OIML, API MPMS, or local custody transfer approvals |
| Insufficient grounding | Signal noise; erratic readings | Ground meter independently; use shielded cables |
| No spare parts or calibration plan | Extended downtime; measurement uncertainty | Plan for spare tubes and calibration services |
8. Applicable Standards
| Standard | Scope |
|---|---|
| ISO 10790:2015 | Measurement of fluid flow in closed conduits—Guidance to the selection, installation and use of Coriolis flowmeters |
| API MPMS Chapter 5.6 | Measurement of liquid hydrocarbons by Coriolis meters |
| OIML R 117 | Dynamic measuring systems for liquids other than water |
| OIML R 137 | Gas meters |
| IEC 60529 | Ingress protection (IP code) |
| IEC 60079 | Explosive atmospheres—equipment certification |
9. Why Choose Anhui Tiankang for Coriolis Flowmeters?
Anhui Tiankang (Group) Co., Ltd. has been manufacturing industrial instruments for nearly five decades. Our Coriolis flowmeters are designed for accurate, reliable mass flow measurement in the most demanding process applications.
Product portfolio:
| Model | Type | Key Features |
|---|---|---|
| TK-CFM Standard | Dual curved tube | ±0.1% accuracy, 100:1 turndown, 4–20 mA + HART, DN15–DN200 |
| TK-CFM High Accuracy | Dual curved tube | ±0.05% accuracy, custody transfer, OIML R117, DN15–DN150 |
| TK-CFM Straight Tube | Straight tube | Hygienic, drainable, 3A/EHEDG, DN15–DN100 |
| TK-CFM Sanitary | Straight tube | Tri-clamp, CIP/SIP, food and pharmaceutical |
| TK-CFM Ex | All types | Ex d IIC T6 / Ex ia IIC T6 for hazardous areas |
Key specifications:
Sizes: DN15 to DN300
Accuracy: ±0.05% to ±0.5% of mass flow (model-dependent)
Turndown: Up to 100:1
Pressure rating: Up to 1,000 bar (model-dependent)
Temperature range: -40°C to +350°C (model-dependent)
Tube materials: 316L SS, Hastelloy C-276, Titanium, Zirconium
Output: 4–20 mA, pulse, RS485/Modbus, HART, Profibus PA
Protection: IP65, IP67, IP68
Ex certification: Ex d IIC T6, Ex ia IIC T6
Custody transfer: OIML R117, API MPMS compliant (high-accuracy models)
Core advantages:
Complete certifications: CCC Ex, ATEX, IECEx, SIL, OIML
CNAS-accredited laboratory: Full flow calibration and performance testing
Engineering support: Sizing calculations, material selection, installation guidance
Proven track record: Long-term supplier to CNPC, Sinopec, CNOOC, and international EPC projects
One-stop supply: From flowmeters to cables to Ex glands—one supplier, one interface
10. Conclusion
Coriolis flowmeters are the most accurate and versatile mass flow measurement technology available. They measure mass flow directly, provide multi-variable output, and maintain accuracy across a wide turndown. They are the preferred choice for custody transfer, chemical dosing, and any application where product quality and financial accuracy are critical.
Key takeaways:
| Selection Step | Key Principle |
|---|---|
| Application | Best for liquids and dense gases; not suitable for large pipes or two-phase flow |
| Sizing | Size by flow range, not pipe size; select smallest meter that handles maximum flow |
| Accuracy | ±0.05% to ±0.1% for custody transfer; ±0.1% to ±0.2% for process control |
| Materials | Match tube material to fluid corrosiveness and abrasiveness |
| Installation | Isolate from vibration; zero after installation; eliminate entrained gas |
| Output | 4–20 mA + HART standard; fieldbus for digital integration |
| Certifications | OIML R117 for custody transfer; Ex for hazardous areas; SIL for safety functions |
The most important rule: A Coriolis meter is a precision instrument. It must be properly sized, properly installed, and properly maintained. The cost of proper selection and installation is a few hours of engineering. The cost of poor selection is a meter that never achieves its stated accuracy, a process that cannot be controlled, and a replacement project that could have been avoided.
Remember: Coriolis meters are not the cheapest flow measurement technology, but they are often the most cost-effective over the life of the plant—because they eliminate the need for separate density and temperature transmitters, reduce maintenance, and provide the accuracy that custody transfer and quality control demand.
Contact Us
For Coriolis flowmeter selection advice, sizing calculations, or project quotations, please contact:
Yin Shuangjie
International Sales Manager
📧 Email: [email protected]
📱 WhatsApp / Zalo: +86 17856068126
🌐 Website: http://www.tiankang-global.com/
Anhui Tiankang – Your partner for reliable Coriolis flow measurement solutions.
