The dew point thermometer for compressed air is a mobile testing device for monitoring the quality of compressed air on stationary and mobile compressed air generators. This dew point thermometer measures the temperature, the relative humidity, H2O and calculates the current dew point up to an ambient pressure of 20 bar. Thanks to the sintered cap, the dew point thermometer in the pressure lines is protected from dirt, moisture and high flow speeds. This increases the service life of the dew point thermometer's sensors.

The data memory of the dew point thermometer enables the course of the measurement parameters to be recorded in a pressure line. The data recorded by the dew point thermometer is permanently stored in the internal memory. The memory can be read out directly on the dew point thermometer. The dew point thermometer can also be connected to an operating system independent computer via the micro USB interface. This is made possible because the dew point thermometer is recognized as a mass data storage device. The data saved by the pressure dew point measuring device are saved in CSV format. The stored measurement data can thus be evaluated using any spreadsheet program.

Lots of industrial processes (automotive, chemical, packaging, sealing, pneumatics, equipment maintenance, devices for painting, cleaning processes, medical sphere etc.) cannot be carried out without compressed air (under a very high pressure). The quality of the compressed air in not unimportant, and for some processes it is crucial. Pressure dew point is one of the parameters which is deviating from the norm, may cause serious damage to the machines, production lines and final products. Since, it goes about increased pressure on gas, it should be noted that the value of the dew point also changes and differs from the atmospheric dew point. The higher the pressure, the higher the pressure dew point temperature (Dalton’s Law). The consequences of the wrong dew point in the compressed air during some industrial process may even lead to shut down of the system, blockage of the pipelines and breakage of the equipment. A lot depends on the process itself. If it goes about food production, excessive amount of water (condensate), arising as a result of the wrong dew point, leads to mold and bacteria formation in the products, very short shelf life, bad vacuum packaging. If the water drops in excessive amount get into sprays and paints produced for painting industry, the material’s quality decreases tremendously. Similar effect occurs in cosmetics or pharmaceutical production.

Necessity and frequency of the application of the measuring tools for monitoring dew point levels in the compressed air is determined by the process (drying, food production and packaging of the products, instrument air require a special attention). There, where deviations may bring to serious damages, it should be done continuously and with the reliable equipment. The latter must be calibrated in accordance with the producer’s recommendations in order to ensure the most reliable and accurate results.

The quality of the compressed air is clearly defined in the International guidelines, and application of the measuring sensors helps the producer to comply with the ISO standards concerning compressed air quality (Classes 1-6), which implies presence of particles, oil and of course permissible pressure dew point. The whole system should work correctly, it means correct pressure and temperature regulation, clean working area, ventilation and filtering, and of course maintenance of the permissible limits – only then any production or industrial process may run flawlessly and with maximum performance.

Gas mixtures can contain water vapour. If these gas mixtures are cooled, the absorption capacity for gaseous water also decreases with the temperature. The dew point or dew point temperature is the temperature at which saturation with water vapour is reached. If the gas mixture is cooled below this temperature, part of the water vapour becomes liquid water, i.e. mist in the gas or dew or condensation on cold water-repellent surfaces. Dew water is also frequently observed in everyday life, for example on mirrors after bathing or showering, on pot lids when cooking, or on glasses when glasses wearers come in from the cold into a warm room. However, the dew point is not only dependent on the moisture content and temperature of a gas, but also on its pressure. When the gas is compressed, its saturated vapour pressure is also increased and thus the associated pressure dew point rises. So, in the case of the compressed gad, the condensation water is separated already at high temperatures. The pressure dew point, like the dew point for expanded gases, is given in degrees Celsius and must always be given together with the pressure to which it applies. A low value for the pressure dew point means that the compressed gas contains little water vapour.

For the processes in which water must not be allowed to form in the gas- or compressed air-filled lines and containers, the pressure dew point can be used as a controlled variable. It can either serve as a reference value for the relative humidity at specific temperatures and pressure or be compared directly with the process and ambient temperatures. If the measured pressure dew point is too high, the process can be interrupted or, if necessary, influenced to prevent damage or failure of the equipment or spoilage of the processed products. In moisture-sensitive compressed air systems or processes, moisture is often removed from the compressed air generated by means of special equipment before it is introduced there. The effectiveness of the processes and equipment used for drying can be checked, among other things, by measuring the pressure dew point.