Moisture detection plays a vital role in various fields. Whether in the chemical, agricultural, food production or pharmaceutical industries, accurately measuring the moisture content of substances is essential for quality control and production processes. At present, the detection methods of solid material moisture mainly include direct measurement and indirect measurement.

1. Indirect measurement methods

Among the indirect measurement methods, infrared absorption method has attracted much attention because of its characteristics of fast, high precision and non-contact. However, it can only measure the moisture content of the surface of the substance, is sensitive to the substance and color, and cannot measure black matter. In addition, the high cost of equipment is also one of the disadvantages of this method.

1, infrared absorption method – using the principle of material absorption of infrared wavelength light, determine the moisture content. Although fast, high-precision, non-contact measurement, it can only measure surface moisture, and is sensitive to substance and tone, and the cost is high.

2, microwave method – the use of high-frequency radio waves on the dielectric constant and dielectric loss changes of the substance, to determine the moisture content. However, the accuracy of the material with uneven particles is poor.

3, neutron method – through the collision of neutrons and water molecules, determine the number of slow neutrons to determine the water content. However, the scope of application is affected by substance density and hydrogen-containing substances.

4, electrical measurement method – including capacitance method and resistance method, suitable for substances with different dielectric constants. The structure is simple and the cost is low, but the measurement accuracy is not high.

Several methods of moisture detection are discussed

Two, direct measurement method – drying weight loss method

Drying weight loss method is one of the most widely used direct measurement methods at present. The method is suitable for solid, liquid, semi-solid and other substances, and has the advantages of simple operation and low cost. However, this method is difficult to measure the samples with high water content, because the samples with high water content are prone to changes in volatile substances during the drying process, resulting in inaccurate weighing results, which need to be corrected by secondary drying method and other methods.

1, direct drying method – under normal pressure, the use of constant temperature drying, weighing samples before and after the weight difference to calculate the moisture content. The equipment includes electric thermostatic drying oven, weighing tray and balance.

2, high temperature timing method – drying at a higher temperature (about 130 ° C) for a short time to determine the moisture content. The measurement is fast but the accuracy is poor.

3, tunnel oven method – similar to the high temperature timing method, but the measurement process is continuous, simple operation.

4, secondary drying method – suitable for samples with high moisture content, through two drying measurements to reduce the error.

5, vacuum drying method – suitable for samples that are not easy to decompose at high temperatures, reduce the steam pressure of water to make water volatilize at lower temperatures.

Several methods of moisture detection are discussed

Several methods of moisture detection are discussed

While addressing the limitations of the measurement method, the researchers are also looking to develop more accurate and faster moisture detection techniques. This includes the use of advanced data processing, machine learning and artificial intelligence, combined with traditional measurement methods, to achieve a more accurate and efficient measurement of moisture content. In short, moisture detection is an indispensable part of the production process in various industries, and the continuous improvement of its measurement methods and technological innovation are of great significance to improve product quality and reduce production costs.