How to determine reasonable error of measurement value of bimetallic thermometer?

Bimetallic thermometer is a kind of measuring temperature instruments, mainly used in chemical and petrochemical industry, power engineering, food, machinery manufacturing, and general factory construction. As all of the measuring instruments, bimetallic thermometer to use after a period of time error of measured values have occasionally happen. This is means that a thermometer is broken? In fact can't speak so, under normal circumstances, we demand bimetallic thermometer need on a regular basis ( 6 months) Verification, verification will need to calibration, the calibration process will involve the issue of measurement error. So how to determine the error value of bimetallic thermometer is reasonable? The reasonable error is also known as temperature compensation, it is produced by the process of bimetallic thermometer calibration, the calibration by bimetallic thermometer and standard thermometer will have a margin of error, the error value is known as temperature compensation, can also be called a reasonable error. Later in the use of the bimetallic temperature timing will be considering the temperature compensation, according to the calibration value to add and subtract the actual temperature, so the final reading is correct.