Flow measurement is critical in a wide range of industries including oil and gas, chemical processing, pharmaceutical, food and beverage, and many others. Process optimization, quality control, and regulatory compliance must be able to precisely monitor the rate at which fluids, whether liquids or gases, flow through a system. As a result, mass flow meters have evolved as an indispensable tool for accurately measuring flow and delivering reliable data for vital decision-making.
Mass flow meters assess fluid mass flow rate, which is a more accurate and dependable method than volumetric flow measurement. They use different methods to determine the mass flow rate of fluids, such as the Coriolis and Thermal principles.
Coriolis and thermal mass flow meters are two popular types of mass flow meters, each with its own set of pros and disadvantages. This blog post will compare the operating principles, applications, and performance characteristics of Coriolis and Thermal mass flow meters. Understanding the distinctions between these two types of meters is critical for picking the best technology for your flow-measuring requirements. So let’s look at the basics of Coriolis and Thermal mass flow meters and see what makes them distinctive.
1. Coriolis Mass Flow Meter
A Coriolis mass flow meter is a device that measures fluid mass flow rate. A Coriolis mass flow meter creates vibrations in the tube through which the fluid flows.
The Coriolis mass flow meter uses the Coriolis effect to measure fluid flow. It comprises a metal vibrating U-shaped tube through which the fluid passes. As the fluid reaches the meter, it divides into two streams, each flowing through one side of the tube. Sensors measure the tube’s vibration, which is induced by Coriolis forces caused by the fluid’s mass and velocity. Because of these forces, the tube twists, generating a phase shift between the two sides. The mass flow rate of the fluid can be calculated by studying this phase difference. The meter measures the mass flow rate directly without requiring extra measurements. It is dependable even in changing fluid characteristics, making it appropriate for various applications.
1.1. Advantages of Coriolis Mass Flow Meter
- Direct measurement of mass flow rate.
- Accuracy and precision.
- Wide range of fluid compatibility.
- Immunity to fluid density and viscosity variations.
- No need for additional density or temperature measurements.
- Low-pressure drop.
- High turndown ratio.
- Minimal maintenance requirements.
- Wide range of applications in different industries.
- Ability to measure multiple parameters simultaneously (mass flow, density, temperature, etc.).
1.2. Limitations of Coriolis Mass Flow Meter
- Limited turndown ratio in some models.   Â
- High initial cost compared to other flow meter technologies.
- Susceptible to abrasion and damage in applications with particulate-laden fluids.
- Limited suitability for low-flow applications due to resolution limitations.
- Size and weight restrictions in larger pipe sizes.
- Sensitivity to external vibrations and mechanical disturbances.
- Limited resistance to high pressures and extreme temperature conditions.
- Challenging installation and orientation requirements for accurate measurements.
- Possible calibration drift over time, requiring periodic recalibration.
- Complex electronics and signal processing may introduce potential points of failure.
2. Thermal Mass Flow Meter
A thermal mass flow meter is a device that measures the flow rate of fluids using the thermal dispersion principle. It detects heat transfer from a heated sensor to a flowing fluid.
Thermal mass flow meters operate on the premise of measuring heat transfer between a heated sensor and the flowing stream. A heated sensor or probe in contact with the fluid is used in these meters. As the fluid flows past the sensor, convection absorbs heat from the sensor. The heat transfer rate is related to the fluid’s mass flow rate. Temperature sensors measure the temperature differential between the heated sensor and the fluid. The thermal mass flow meter estimates the mass flow rate by assessing the fluid’s temperature differential and known thermal parameters. This working principle enables thermal mass flow meters to accurately measure the flow rate of gases without additional pressure or temperature compensation, making them suitable for various applications in industries such as process control, environmental monitoring, and HVAC systems.
2.1. Advantages of Thermal Mass Flow Meter
- Direct mass flow measurement.
- Wide range of fluid compatibility.
- High accuracy and precision.
- Low-pressure drop.
- Fast response time.
- No moving parts.
- Wide range of flow rates.
- Wide operating temperature range.
- Low maintenance requirements.
- Suitable for both clean and dirty fluids.
2.2. Limitations of Thermal Mass Flow Meter
- Limited accuracy at low flow rates.
- Susceptible to thermal conductivity variations of the fluid.
- Potential for sensor fouling or clogging in dirty or particulate-laden fluids.
- Limited suitability for measuring multiphase or non-homogeneous fluids.
- Limited rangeability for extraordinarily high or low flow rates.
- Sensitivity to changes in fluid composition or gas mixtures.
- Restricted suitability for high-pressure applications.
- Calibration drift over time, requiring periodic recalibration.
- Inaccuracy in measuring low-density or low-viscosity fluids.
- Vulnerability to external vibrations or mechanical disturbances.
3. Comparison between Coriolis and Thermal Mass Flow Meters
3.1 Accuracy and repeatability
- Coriolis Mass Flow Meter: Provides exact measurements even at low flow rates due to its excellent accuracy and repeatability.
- Thermal Mass Flow Meter: Provides good accuracy and repeatability but has limits at low flow rates and with non-homogeneous fluids.
3.2 Flow range capability
- Coriolis Mass Flow Meter: A high turndown ratio can measure low and high flow rates.
- Thermal Mass Flow Meter: This has a low turndown ratio and is best suited for moderate to high flow rates but may have limits at low flow rates.
3.3 Compatibility with different fluid types
- Coriolis Mass Flow Meter: Can be used with various fluids, including liquids and gases.
- Thermal Mass Flow Meter: Generally applicable to gases and some liquids but limited to certain fluid types.
3.4 Pressure drop considerations
- Coriolis Mass Flow Meter: A minimal pressure drop reduces energy losses.
- Thermal Mass Flow Meter: Has a modest pressure drop and so has less impact on the system.
3.5 Installation and maintenance requirements
- Coriolis Mass Flow Meter: Installation, such as precise pipe orientation, may be more complicated. In addition, periodic maintenance is required, including sensor cleaning.
- Thermal Mass Flow Meter: Less challenging to install and operate, typically requiring little maintenance.
3.7 Cost-effectiveness
- Coriolis Mass Flow Meter: Due to the intricacy of the technology, the initial cost is generally higher.
- Thermal Mass Flow Meter: Less expensive in terms of initial investment.
3.8 Application-specific considerations
- Coriolis Mass Flow Meter: Ideal for custody transfer applications requiring precise measurement and outstanding reliability.
- Thermal Mass Flow Meter: Ideal for applications requiring a quick response time and gas compatibility, such as environmental monitoring and HVAC systems.
The performance and applicability of both Coriolis and Thermal Mass Flow Meters may vary based on the brand and model and the application requirements.
4. Conclusion
Coriolis and Thermal Mass Flow Meters have distinct advantages and are appropriate for specific applications. The Coriolis Mass Flow Meter is perfect for custody transfer and critical process control applications because of its accuracy, repeatability, and adaptability. Accuracy, flow range capability, fluid compatibility, pressure drop considerations, installation requirements, maintenance, and cost-effectiveness are all essential issues. The most suitable flow meter for precise and reliable flow measurement can be selected by extensively examining an application’s specific needs and limits and consulting with specialists.