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Measurement of dew point temperature: The dew point temperature of compressed air is measured using a dew point meter. There are two common types of instruments used for this purpose: 1) Mirror dew point meters, which work by using refrigeration to cool the gas being measured to a certain temperature; the water vapor present in that gas then condenses on the mirror surface, and the temperature at which condensation occurs is determined using optical principles. In principle, this method enables the measurement of any dew point temperature as long as there are sufficient cooling measures. However, the problem with this method is that: a) it has high requirements for the gas being measured, as any impurities or contaminants can lead to measurement errors; b) due to the use of refrigeration, its working principle is relatively complex, and it takes some time for each measurement to be carried out. Therefore, such dew point meters are generally not used for online monitoring and field testing, but rather in laboratories and similar settings. 2) Capacitance/resistance dew point meter. These types of dew point meters have the advantages of small size, ease of portability, and a wide measurement range. Their sensors are usually alumina sensors, enabling them to measure dew point temperatures as low as -100°C (for example, the MD-10PP model manufactured by our company has a measurement range of 0 to -80°C). The downside of these dew point meters is that they can generally only measure dew point temperatures at atmospheric pressure; moreover, the dew point sensors may exhibit negative offsets, which requires them to be calibrated by a qualified testing agency every year. Well-known manufacturers of dew point meters include the British companies MISHELL and SHAW, as well as the Finnish company Vaisala, among others