Introduction to Pressure Gauge Selection

The accuracy level of a pressure gauge is expressed as the percentage of allowable error to the range of the gauge. It is generally divided into seven levels: 0.5, 1, 1.5, 2, 2.5, 3...

The meaning of pressure gauge accuracy level: The accuracy level of a pressure gauge is expressed as the percentage of allowable error to the range of the pressure gauge. It is generally divided into seven levels: 0.5, 1, 1.5, 2, 2.5, 3, and 4 (level 3 and 4 are not used on boilers). The smaller the value, the higher the accuracy

For example, for a pressure gauge with a dial range of 0-2.5 MPa and an accuracy of 2.5 levels, the allowable error between the pressure value indicated by its pointer and the actual pressure value of the measured medium shall not exceed 2.5 MPa x 2.5%=± 0.062 5 MPa; When the pressure gauge indicates a pressure of 0.8 MPa, the actual air pressure is between 0.737 5 and 0.862 5 MPa

From this, it can be seen that the actual error of the pressure gauge is not only related to accuracy, but also to the range size of the pressure gauge

When the range is the same, the higher the accuracy (i.e. the smaller the number), the smaller the allowable error of the pressure gauge

When the accuracy is the same, the larger the range, the greater the error of the pressure gauge

Selection of Pressure Gauges

The selection of pressure gauges should be based on the requirements of use, and on the premise of meeting the technical requirements of the process, it should be comprehensively considered from multiple aspects based on the principle of saving and practicality, to achieve a reasonable selection of accuracy level, range, type and model.

1. Determination of accuracy level for pressure gauges

The accuracy levels for precision pressure gauges are 0.1, 0.16, 0.25, and 0.4, respectively.

; The accuracy levels of general pressure gauges are 1.0, 1.6, 2.5, and 4.0, respectively

The method for selecting the accuracy level of pressure gauges: The accuracy level should be determined based on the requirements of production technology, economic practicality, testing methods, etc., and the allowable error required by the small value of the measured pressure

2. Selection of pressure gauge range

1) When measuring stable pressure, the large working pressure should not exceed 2/3 of the range.

2) When measuring pulsating pressure, the large working pressure should not exceed 1/2 of the range. 3) When measuring high pressure, the large working pressure should not exceed 3/5 of the range. 4) To protect measurement accuracy, the small working pressure should not be lower than 1/3 of the range

According to the above principles, calculate a value based on the measured pressure, and select a value slightly greater than this value from the range series of the pressure gauge to determine the selected range

3. Selection of pressure gauge types

Different types of pressure gauges should be selected for measuring different media and usage environments

1). For general media such as air, water, steam, oil, etc., ordinary pressure gauges can be used.

2) For special media, one-on-one pressure gauges are required, such as ammonia pressure gauges for ammonia; Oxygen class oxygen pressure gauge; Pressure gauges for hydrogen gas; Acetylene pressure gauges are used for acetylene products, etc

For general corrosive media and corrosive gas environments, stainless steel pressure gauges can be selected

For measuring the pressure of liquids, gases, or media with solid planktonic substances that have high viscosity, are prone to crystallization, are highly corrosive, and have high temperatures, a diaphragm type pressure gauge is selected

5). For pressure measurement in pulse media and mechanical vibration scenarios. Select a seismic resistant pressure gauge

When there is a requirement for remote transmission, a remote transmission pressure gauge can be selected. The remote transmission signals include current type, resistance type, and voltage type

When there are control and protection requirements, an electric contact pressure gauge can be selected

When there are explosion-proof requirements, explosion-proof type should be selected, such as explosion-proof electric contact pressure gauge