Accuracy class of electromagnetic flowmeter

Project Overview

The accuracy level of electromagnetic flowmeter is divided into

Electromagnetic flowmeter is a flow measurement instrument used in industrial process control. Its measurement accuracy directly affects production efficiency and product quality. In order to standardize the performance indicators of electromagnetic flowmeters, corresponding accuracy grade standards have been formulated internationally to facilitate users to choose appropriate instruments according to actual needs. This article will introduce in detail the accuracy grade classification, influencing factors and selection suggestions of electromagnetic flowmeters.

1. Classification of accuracy levels of electromagnetic flowmeters

The accuracy level of electromagnetic flowmeters is usually expressed in percentage, which refers to the allowable error range between the measured value and the true value. . According to the international standard IEC 60751 and the national standard GB/T 9736, the accuracy levels of electromagnetic flowmeters are mainly divided into the following categories:

Level 0.2: Level, suitable for applications that require extremely high measurement accuracy. Occasions, such as trade settlement, scientific research, etc. Level 0.5: Level, suitable for occasions that require high measurement accuracy, such as flow measurement and control in chemical, pharmaceutical, food and other industries. Level 1.0: Commonly used accuracy level, suitable for most industrial process control, such as water treatment, steel, electric power and other industries. Level 1.5 and Level 2.0: Low accuracy levels, suitable for occasions that do not require high measurement accuracy, such as agricultural irrigation, sewage treatment, etc. It should be noted that different countries and regions may have different accuracy classification standards. For example, the American national standard ANSI/ISA 75.01 divides the accuracy levels of electromagnetic flowmeters into four levels: 0.25%, 0.5%, 1.0% and 2.0%.

2. Factors affecting the accuracy of electromagnetic flowmeter

The measurement accuracy of electromagnetic flowmeter is affected by many factors, mainly including the following aspects:

2.1 Fluid Characteristics

Conductivity: The working principle of the electromagnetic flowmeter is based on Faraday’s law of electromagnetic induction, which requires the measured fluid to have a certain conductivity. If the conductivity is too low, the measurement sensitivity will be reduced and the measurement error will be increased. Viscosity: Highly viscous fluids increase fluid resistance and affect the linearity and repeatability of the flow meter. Density: Changes in fluid density will affect the zero-point stability of the flow meter. Temperature: Temperature changes affect the conductivity and viscosity of the fluid, which in turn affects measurement accuracy. Therefore, it is necessary to choose an appropriate temperature compensation method. 2.2 Installation conditions

Length of straight pipe section: In order to ensure measurement accuracy, a long enough straight pipe section needs to be reserved upstream and downstream of the electromagnetic flowmeter to eliminate the turbulent flow generated by pipeline elbows, valves and other components. Grounding: Good grounding can effectively suppress electromagnetic interference and improve measurement stability. Vibration: Strong vibration will affect the stability of the sensor signal and increase measurement errors. Vibration reduction measures need to be taken. 2.3 The instrument itself

Sensor manufacturing accuracy: The sensor is the core component of the electromagnetic flowmeter, and its manufacturing accuracy directly affects the measurement accuracy. Transmitter performance: Transmitter linearity, stability andAnti-interference ability also affects measurement accuracy. Electrode material: The choice of electrode material should match the fluid being measured to avoid electrochemical corrosion and signal attenuation. 3. Recommendations for selecting electromagnetic flowmeter

Selecting a suitable electromagnetic flowmeter requires consideration of the following aspects:

3.1 Accuracy level

According to actual application Choose the appropriate accuracy level for the measurement accuracy requirements. For occasions where measurement is required, a class 0.2 or class 0.5 electromagnetic flowmeter should be selected. For general industrial process control, you can choose a class 1.0 electromagnetic flowmeter. For occasions where the accuracy requirements are not high, you can choose a class 1.5 or class 2.0 electromagnetic flowmeter.

3.2 Fluid Characteristics

Select an appropriate electromagnetic flowmeter based on the conductivity, viscosity, density, temperature and other characteristics of the fluid being measured. For low conductivity fluids, you can choose electromagnetic flowmeters with low-frequency excitation or dual-frequency excitation. For high viscosity fluids, you can choose plug-in or clamp-on electromagnetic flowmeters. For high-temperature fluids, it is necessary to choose an electromagnetic flowmeter made of high-temperature resistant materials.

3.3 Installation conditions

Select the appropriate electromagnetic flowmeter according to the actual installation conditions. If the on-site space is limited and sufficient straight pipe sections cannot be reserved, you can choose an electromagnetic flowmeter with shorter straight pipe section requirements. If there is strong electromagnetic interference on site, you can choose an electromagnetic flowmeter with strong anti-interference ability.

3.4 Cost Budget

The prices of electromagnetic flowmeters with different accuracy levels, functions and brands vary greatly. On the premise of meeting the measurement accuracy and performance requirements, products with high cost performance should be selected.

4. Summary

The accuracy level of the electromagnetic flowmeter is one of the important indicators for selecting the instrument. Understanding the applicable scope of different accuracy levels and the factors that affect measurement accuracy can help users choose a suitable electromagnetic flowmeter, improve measurement accuracy, and ensure production safety and product quality.