Introduction to the correct selection of pressure gauges

(1) For pressure gauges with measuring ranges installed on boilers and pressure vessels, the maximum measuring range (limit value of the scale on the dial) should be compatible with the working pressure of the equipment. The range of the pressure gauge is generally 1.5 to 3 times the working pressure of the equipment, preferably 2 times. If the range of the selected pressure gauge is too large, due to the same accuracy of the pressure gauge, the larger the range, the greater the absolute value of the allowable error and the deviation of the naked eye observation, which will affect the accuracy of the pressure reading; otherwise, if the pressure gauge is selected If the measuring range is too small, the working pressure of the equipment is equal to or close to the scale limit of the pressure gauge, which will cause the elastic element in the pressure gauge to be in the maximum deformation state for a long time, and it is easy to produce permanent deformation, causing the error of the pressure gauge to increase and the service life to decrease. In addition, the range of the pressure gauge is too small. In case of overpressure operation, the pointer crosses the maximum range and approaches zero, which causes the operator to have an illusion and cause a greater accident. Therefore, the pressure range of the pressure gauge should not exceed 60 to 70% of the scale limit.

(2) Measurement accuracy The accuracy of the pressure gauge is expressed as a percentage of the allowable error in the limit value of the dial scale. The accuracy level is generally marked on the dial. When selecting a pressure gauge, the accuracy should be determined according to the pressure level of the equipment and the actual work needs. The accuracy of pressure gauges for boilers and low-pressure vessels with a rated steam pressure of less than 2.45 MPa shall not be less than 2.5; the accuracy of pressure gauges of boilers and medium and high-pressure vessels with a rated steam pressure of more than 2.45 MPa shall not be less than 1.5.

(3) Dial diameter To allow the operator to accurately see the pressure value, the dial diameter of the pressure gauge should not be too small. Under normal circumstances, the dial diameter of the pressure gauge used in boilers and pressure vessels should not be less than 100mm. If the pressure gauge is installed higher or farther away from the post, the dial diameter should also be increased.