Coriolis mass flow meter and electromagnetic flow meter are common flow measurement instruments, but their principles and scope of application are different. This article will compare these two flow meters to better understand their characteristics and application scenarios.

1. Coriolis mass flow meter

1. principle

Coriolis mass flow meter is a flow measurement instrument based on the Coriolis effect, suitable for measuring the mass flow of gases, liquids and multi-phase fluids. The Coriolis effect means that when a current passes through a conductor, a transverse magnetic field is generated on a plane perpendicular to the direction of the current. Coriolis mass flow meters calculate mass flow by measuring the heat generated when a fluid flows through a magnetic field. The basic principle is: when the fluid passes through the thermoelectric pile, a thermoelectromotive force will be generated at both ends of the stack, and its magnitude is proportional to the mass flow rate of the fluid.

2. Advantages

(1) Suitable for measuring mass flow of gas, liquid and multi-phase fluid;

(2) High measurement accuracy, reaching 0.1%;

(3) There is no need to calibrate the fluid density, pressure and temperature of the flow meter;

(4) For fluids at low flow rates, its measurement accuracy is higher than that of electromagnetic flow meter.

3. Disadvantages

(1) The price is higher, usually more expensive than electromagnetic flow meter;

(2) It is only suitable for measuring mass flow and cannot directly measure volume flow;

(3) It has a certain impact on the measurement accuracy of large flow and high viscosity fluids;

(4) It is greatly affected by external magnetic fields and needs to be shielded.

2. Electromagnetic flow meter

1. principle

The electromagnetic flow meter is a flow measuring instrument based on Faraday's law of electromagnetic induction and is suitable for measuring the volume flow of liquids and conductive liquids. Faraday's law of electromagnetic induction means that in a magnetic field, when a current passes through a conductor, a potential difference will be generated on both sides of the conductor. Electromagnetic flow meter use this principle to calculate the volumetric flow rate of a liquid by measuring the potential difference generated when the liquid flows through a magnetic field.

2. Advantages

(1) Suitable for measuring the volume flow of liquids and conductive liquids;

(2) Wide measurement range, applicable to small flow to large flow;

(3) Suitable for measurement of high temperature, high pressure and corrosive liquids;

(4) Remote transmission and control can be achieved, and it is suitable for automated production lines and remote monitoring systems;

(5) High accuracy, usually 1% or higher.

Disadvantages (1) Unable to measure non-conductive liquids;

(2) It is sensitive to magnetic field interference and changes in liquid media, which may lead to a decrease in measurement accuracy;

(3) The price of the electromagnetic flow meter itself is relatively high and is not suitable for some low-cost applications.

Precautions for use (1) During installation, the direction of the fluid inlet and outlet should be ensured to avoid eddy currents and liquid splashing at the installation location;

(2) Pay attention to the conductivity of the liquid. For liquids with low conductivity, it may be necessary to install a reducer to improve measurement accuracy;

(3) The electromagnetic flow meter should be calibrated and maintained regularly, and components such as measuring pipes and sensors should be cleaned to ensure its accuracy and stability.

Comparison There are major differences between electromagnetic flow meter and Coriolis mass flow meter in terms of measurement range, measurement principle, and applicable fluids. Coriolis mass flow meter is suitable for measuring the mass flow of gases, liquids and multi-phase fluids. It can directly measure the density and temperature of the fluid with high accuracy, but it cannot measure non-conductive fluids. The electromagnetic flow meter is suitable for measuring the volume flow of liquids and conductive liquids. It can be suitable for measuring high temperature, high pressure and corrosive liquids, and usually has high accuracy. However, electromagnetic flow meter cannot measure non-conductive liquids and are sensitive to magnetic field interference and changes in liquid media.

When selecting a measuring instrument, an appropriate flow meter should be selected based on the actual application scenario and measurement requirements to avoid misuse, which may lead to a decrease in measurement accuracy or failure to perform measurements. At the same time, you need to pay attention to operating specifications and maintenance requirements during use, and perform regular calibration and maintenance to ensure measurement accuracy and stability.