What is the difference between Coriolis and thermal mass flow meter?

What is the difference between Coriolis and thermal mass flow meter?

Coriolis mass flowmeter and thermal mass flowmeter are two common instruments that directly measure mass flow rate, but they have some differences in principle, structure, application etc. The following are the main differences between them.

1. Measurement Principle

Coriolis Mass Flow Meters

Based on the Coriolis Effect, when the fluid flows through the vibrating tube, the fluid inertia will cause the pipe to produce phase difference or deformation. The mass flow rate can be directly calculated by detecting the deformation (such as phase difference, frequency change, etc.). It can measure the mass flow rate, density and temperature simultaneously.

Thermal Gas Mass Flow Meter

Based on the principle of thermal diffusion, by heating the fluid and measuring the heat carried away by the fluid flow (or temperature change), we can calculate the mass flow rate. Usually divided into two modes.

Constant Power Method ---- Keep the heating power constant and measure the temperature difference.

Constant Temperature Difference Method ---- Keep the temperature difference constant and measure the required heating power.

2. Applicable Fluid

Coriolis Mass Flow Meter

Suitable for liquids, gases, high viscosity fluids (such as petroleum, chemical slurries) and multiphase flows (gas-liquid mixture). No requirements on fluid conductivity and dielectric constant.

Thermal Mass Flow Meter

Mainly used for gases (such as air, natural gas, nitrogen, etc.) and low viscosity liquids. Not suitable for multiphase flow or dirty fluid containing particles, as particles may affect heat transfer.

3. Accuracy and Performance

Coriolis Mass Flow Meter

High accuracy (usually ±0.1%~±0.5%), directly measures mass flow rate, not affected by temperature and pressure changes. Output the data of density and temperature simultaneously. Higher pressure loss. (Because the fluid needs to flow through the curved vibrating tube.)

Thermal Mass Flow Meter

Medium accuracy (usually ±1%~±3%), depending on the thermophysical properties of the fluid (such as specific heat capacity). It has good effect on gas measurement, but it’s sensitive to temperature and pressure changes and needs compensation. Almost no pressure loss (with bypass or insertion design).

4. Structure and Installation

Coriolis Mass Flow Meter

The structure is complex, including vibration tube and precision sensor, and the volume is large. It has high installation requirements (need to avoid external vibration interference), and usually requires fixed support. Suitable for applications with smaller pipe sizes (generally ≤ DN300).

Thermal Mass Flow Meter

Simple structure, divided into insertion type or tubular type, and small size. Flexible installation, especially suitable for large diameter gas flow measurement (such as flues and ventilation ducts). Not sensitive to vibration, but the flow field must be stable (upstream and downstream straight pipe sections are required).

5. Cost and Maintenance

Coriolis Mass Flow Meter

Expensive (especially for large diameters), and high maintenance costs. Long-term stability is good, but the vibration tube may be corroded or worn.

Thermal Mass Flow Meter

Lower cost and simple maintenance (no moving parts). The sensor may be affected in accuracy due to fouling or high temperature aging.

6. Typical Applications

Coriolis Mass Flow Meter

Petrochemical (crude oil, liquefied gas), food and beverage (syrup), pharmaceutical and other applications requiring high-precision mass flow rate. When density or concentration needs to be measured simultaneously (such as mixed solutions).

Thermal Mass Flow Meter

Gas flow monitoring (such as semiconductor industry process gases, HVAC systems, compressed air). Large diameter and low velocity gas measurement (such as chimney emission monitoring).

7. Summary of Selection Suggestions

Between Coriolis and thermal mass flow meter, if you need high-precision, multi-parameter measurement (especially for liquids or complex fluids), choose Coriolis mass flowmeters. If you need high-precision, multi-parameter measurement (especially for liquids or complex fluids), choose Coriolis mass flowmeters. Pay attention to the effects of fluid properties (viscosity, cleanliness) and environmental conditions (vibration, temperature) on the flow meter.