In order to ensure that the elastic element can work reliably within the safe range of elastic deformation, when selecting the range of the pressure gauge, sufficient margin must be left according to the magnitude of the measured pressure and the speed of pressure change. Therefore, the upper limit value should be higher than the maximum pressure value that may be possible in the process production. When measuring stable pressure, the maximum working pressure should not exceed 2/3 of the measurement upper limit value; When measuring pulsating pressure, the maximum working pressure should not exceed 1/2 of the measurement upper limit value; When measuring high pressure, the maximum working pressure should not exceed 3/5 of the measurement upper limit. The minimum value of the measured pressure should generally not be less than one-third of the upper limit value of the instrument measurement. Ensure the accuracy and sensitivity of instrument measurement results.

After calculating the upper and lower limits of the instrument based on the maximum and minimum values of the measured parameter, these values cannot be directly used as the measurement range of the instrument. When selecting the upper limit value of the instrument scale, we should choose from the standard series specified by the country. The standard series of pressure gauge measurement range includes: -0.1-0.06, 0.15; 0-1,1.6,2.5,4,6,10X10 "MPa (where n is a natural integer) Can be positive or negative).