tyhjiömittare

A tyhjiömittari, or vacuum gauge in English, is an instrument used to measure pressure in a vacuum. This pressure is typically much lower than atmospheric pressure. Tyhjiömittarit are essential in many scientific and industrial applications where precise control of low-pressure environments is required.

There are several types of tyhjiömittarit, each suited for different pressure ranges and applications. For example, mechanical gauges like Bourdon gauges or diaphragm gauges are often used for rough vacuum measurements. Electronic gauges, such as Pirani gauges, thermocouple gauges, and capacitance manometers, are employed for higher vacuum levels and offer greater accuracy. Ionization gauges, including hot-cathode and cold-cathode types, are used for ultra-high vacuum measurements.

The principle of operation varies greatly depending on the type. Mechanical gauges rely on the physical deformation of a component under pressure. Thermal conductivity gauges measure how effectively heat is transferred away from a heated element by the gas molecules present. Capacitance manometers measure the change in capacitance between two electrodes as the pressure difference changes. Ionization gauges work by ionizing gas molecules and measuring the resulting ion current, which is proportional to the pressure.

Tyhjiömittarit find applications in diverse fields. In laboratories, they are used in vacuum chambers for experiments, in mass spectrometry, and in freeze-drying processes. Industrially, they are crucial for semiconductor manufacturing, vacuum coating, distillation, and leak detection in sealed systems. The selection of a tyhjiömittari depends on the required pressure range, accuracy, process compatibility, and cost. Regular calibration is important to ensure the continued accuracy of these instruments.