In the normal conditions of use, the accuracy of the measurement results of the instrument is called the accuracy of the instrument. The smaller the quoted error, the higher the accuracy of the instrument, and the quoted error and the range of the instrument is related to the range of the instrument, so in the use of the same accuracy of the instrument, often take the compression of the range of the instrument, in order to reduce the measurement error. In industrial measurement, in order to facilitate the expression of the quality of the instrument, usually with the accuracy level to indicate the degree of accuracy of the instrument. The accuracy class is the maximum quoted error minus the plus or minus sign and the percent sign. Accuracy level is one of the important indexes to measure the quality of the instrument. China's industrial instrumentation grade is divided into 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, 5.0 seven grades, and marked on the instrument scale or nameplate. Instrument accuracy is customarily referred to as precision, accuracy level is customarily referred to as precision level.
Instrumentation accuracy = (absolute error of the maximum value / instrument range) * 100%
The above calculation formula to take the absolute value of the % is that we see the accuracy of the grade.
Instrumentation accuracy is based on the national regulations allow the size of the error is divided into several levels. The permissible error of a certain type of instrumentation refers to the maximum value of the percentage error allowed in the specified normal conditions. China's process testing and control instrumentation accuracy level of 0.005, 0.02, 0.1, 0.35, 0.5, 1.0, 1.5, 2.5, 4 and so on. The general industrial meter is 0.5 ~ 4 level. The smaller the precision number, the higher the accuracy of the meter.
Reference:
Instrumentation and Automation