The accuracy level is divided by the percentage of its allowable error in the dial scale value. The greater the accuracy level, the greater the allowable error is the larger the scale limit of the dial. The greater the range, the same accuracy level, the absolute value of the pressure value is measured, the greater the allowable error. The precision used is 2.5 or 1.5. If 1 and 0.5 are of high precision, there are already 0.25 figures.

The expression of error is divided into reference error, relative error and absolute error.

Reference error = (absolute error maximum / meter range) x 100%

For example: 2%F.S.

Relative error = (absolute error maximum / instrument measurement value) * 100%

For example: less than 2%

Absolute error refers to how much error deviates from the true value.

For example: < < + 0.01m3/s

Under normal working conditions, the accuracy of instrument measurement is called instrument accuracy. In industrial measurement, in order to facilitate the quality of the instrument, the accuracy level is usually used to indicate the accuracy of the instrument. The accuracy level is the maximum reference error to remove the positive, negative and percentage points. Accuracy level is one of the important indicators to measure the quality of instruments. China's industrial instrument grades are divided into 0.1, 0.2, 0.5, 1, 1.5, 2.5, 5 and seven grades, and are marked on instrument scale scale or nameplate. The accuracy of instrument is customarily known as accuracy, and the accuracy grade is customarily called the accuracy grade.

Accuracy of instrument = (absolute error maximum / instrument range) *100%

The absolute value of the above formula is taken away from%, which is the accuracy level we have seen.

The accuracy of instrument is divided into several grades according to the allowable error size stipulated by the state. The allowable error of a type of instrument is the maximum percentage error allowed under normal conditions. The accuracy level of process detection and control instruments in China is 0.005, 0.02, 0.1, 0.35, 0.5, 1, 1.5, 2.5, 4, etc. The general industrial use table is from 0.5 to 4. The more accurate the accuracy is, the higher the accuracy of the instrument.