Pressure is a state variable, like temperature, and thus also an important measurement variable in industrial metrology. All substances, whether in liquid, vapor or gaseous state, exert a pressure on the walls enclosing them. The physical properties of many substances are inherently pressure-dependent. Pressure therefore describes the state of a gas or liquid.
Pressure measurement is very important for ensuring product quality. It is the only way to ensure that people and equipment are protected from overload. In addition, the measurement of pressure is indispensable as an auxiliary variable for other important measured variables in the application or process.
Probably the most important pressure for life on earth is the atmospheric air pressure. It is generated by the weight of the air envelope surrounding the earth up to a height of about 500 km. Up to this height, where the absolute pressure is zero, its magnitude constantly decreases. In addition, atmospheric pressure is subject to weather-related fluctuations. At sea level, the atmospheric air pressure averages 1013.25 mbar.
Absolute pressure: The absolute pressure is the pressure related to empty space, i.e. zero pressure. It is used in meteorology, altitude measurements, and in the manufacture of vacuum packaging.
Relative pressure: The relative pressure is the pressure related to the air pressure of the environment. Applications are tire pressure control in cars, level measurement in tanks, and medical suction devices.
Differential pressure: The differential pressure is the pressure difference between any two pressures. Areas of application are air-conditioning technology and breathing apparatus.