Why are gas mass flow meters inaccurate?

Importance

Gas mass flow sensors are important in both industrial production and laboratory research. In the chemical, environmental, food and pharmaceutical industries, precise measurement of gas flow is required to ensure process stability and product quality consistency. 

In addition, gas mass flow sensors have a wide range of applications in medical, energy, and aerospace fields. Accurate flow measurement helps to improve productivity, reduce energy consumption and safeguard personal safety. 

Therefore, it is of great significance to analyze the error of gas mass flow sensors to improve their measurement accuracy and stability.

Measurement Methods

Flow measurement methods mainly include direct and indirect measurements. Direct measurement is used to calculate flow by measuring the instantaneous velocity of a fluid as it passes through a pipe of known cross-sectional area. 

Indirect measurement methods calculate the flow rate by measuring physical quantities that are proportional to the flow rate, such as pressure, temperature, and density. These methods are applicable to different scenarios and needs, and the specific choice depends on the characteristics of the measurement object, accuracy requirements and economic considerations.

The Source of Error

1. Measuring principle errors

Errors due to certain theoretical approximations of the flow sensor's measurement principle. For example, certain flow sensors utilize Newton's second law and Bernoulli's equation to calculate flow rates, but in practice the flow in a pipe may not exactly match the assumptions of these theories, and thus may lead to errors. 

In addition, certain flow sensors may base their measurements on physical or chemical principles, but in practical applications there may be limitations or uncertainties in the principles that can lead to errors. To reduce such errors, the sensors may be calibrated and optimized to improve their measurement accuracy and stability.

2. Errors due to environmental effects

Errors due to changes in environmental factors such as temperature, pressure, and humidity. For example, temperature changes may result in changes in pipe size, which can affect the measurement results of the flow sensor. Pressure changes may affect the density and velocity distribution of the fluid, thus affecting the measurement results of the flow sensor. 

Humidity changes may affect the physical properties of the fluid and the performance of the flow sensor, thereby affecting the measurement results. To minimize such errors, the sensor can be environmentally compensated and calibrated. To accommodate measurements under different environmental conditions.

3. Equipment Manufacturing Errors

Errors due to the limitations of the manufacturing process and the nature of the material. For example, there may be certain dimensional or shape errors in the manufacturing process. This results in the geometry or physical properties of the sensor device not meeting the design requirements. This affects the measurement results. 

In addition, inhomogeneities or defects in the nature of the material may also lead to instability in the performance of the device, thus affecting the measurement results. To minimize such errors, high-precision manufacturing processes and high-quality materials can be used. And strict testing and calibration are carried out to ensure that the performance and quality of the equipment meet the design requirements.

4. Signal Processing Errors

Errors may be introduced in the signal processing process, such as signal acquisition, transmission, and processing. For example, there may be sampling frequency and quantization level limitations during signal acquisition, resulting in distortion or loss of signal. Signal attenuation, interference, and noise may exist during signal transmission, leading to distortion or distortion of the signal. 

There may be imperfections in the algorithms or calculation errors in the signal processing process, leading to inaccurate or unstable results. In order to minimize such errors, advanced signal processing techniques and algorithms can be used. And adequate verification and testing are carried out to ensure the accuracy and stability of signal processing.

Methods of error reduction and compensation

1. Optimization of the measurement principle

Improve and optimize the measurement principle to reduce theoretical approximations and uncertainties, thereby increasing measurement accuracy.

2. Improve equipment manufacturing accuracy

Adoption of high-precision manufacturing processes and materials to reduce equipment manufacturing errors, thereby improving measurement accuracy.

3. Environmental Compensation Technology

Compensate for changes in environmental factors such as temperature, pressure, humidity, etc. to adapt to the measurement needs under different environmental conditions.

4. Software Algorithm Optimization

Improve and optimize the signal processing algorithm to increase the accuracy and stability of the algorithm, thus reducing the signal processing error.