The pressure gauge can indicate and record the pressure value, and an alarm or control device can be attached. The pressures measured by the instrument include absolute pressure, atmospheric pressure, positive pressure (customarily called gauge pressure), negative pressure (customarily called vacuum) and differential pressure. Gauge pressure is mostly measured in engineering technology. The international unit of pressure is Pa, and other units are: engineering atmospheric pressure, Pa, millimeter water column, millimeter mercury column, etc.
Pressure is an important parameter in industrial production. For example, if the pressure of a high-pressure vessel exceeds the rated value, it is unsafe and must be measured and controlled. In some industrial production processes, pressure also directly affects the quality and production efficiency of products. For example, in the production of synthetic ammonia, nitrogen and hydrogen are not only synthesized under a certain pressure, but also the pressure directly affects the output.
Extended data
1, u-tube manometer
The measuring range of U-tube manometer is generally 0 ~ 800 mm water column or mm mercury column, and the accuracy is 1. It can measure gauge pressure, vacuum degree, differential pressure and standard deviation manometer, and is used to calibrate flowmeter. Its characteristic is that the zero scale is in the middle of the scale plate, and it is not necessary to zero before use, and the height of the liquid column must be read twice.
2. Bellows pressure gauge
Corrugated pipe, also known as corrugated box, is a thin-walled circular pipe with many concentric annular corrugated folds on its surface. Bellows can be divided into single layer and multi-layer. Under the condition of the same total thickness, the internal stress of multi-layer corrugated pipe is small, which can bear higher pressure and improve its durability. Due to the friction between layers, the hysteresis error of multilayer bellows increases.
3. Hall manometer
Hall manometer is a pressure measuring instrument made of Hall effect. When the measured pressure is introduced, the free end of the spring tube is displaced, which drives the Hall plate to move, changes the magnetic induction intensity exerted on the Hall plate, and then converts it into the change of Hall potential according to the Hall effect, thus realizing the conversion of pressure-displacement-Hall potential.
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