There are two main types of pressure gauges in common use: liquid column gauges and flexible gauges.
Liquid column manometers are used to measure smaller pressures and differential pressures. In the U-shaped tube filled with working liquid (mercury, water, alcohol, etc.), when the pressure at both ends is different, the height difference of the liquid column reflects the difference in pressure between the two sides. The difference in pressure is proportional to the density of the liquid and the difference in height of the liquid column. This kind of pressure gauge structure is simple and inexpensive, but can only be measured in situ, only in small air separation devices and applications.
Small air separation equipment commonly used in the pressure gauge model Y-60 and Y-100, case diameter of 60mm and 100mm, respectively, used in situ instructions; Y-100T or YO-100T (oxygen, forbidden oil) used in the instrument panel. The pressure vacuum gauge is type YZ and is used for the measurement of the inlet pressure of the compressor. Diaphragm, membrane box and bellows and other elastic components of the manometer is commonly used to measure lower pressure (0.1 ~ 10kPa), such as oxygen, nitrogen products pressure measurement, commonly used YEJ-111 membrane box type pressure gauge.
