How long is fixed number of year of the bimetallic thermometer inspection?

Bimetallic thermometer is a common thermometer table, commonly used to measure - 50 to 500 c medium temperature. We often see the bimetallic thermometer according to its header and heat pipe connection mode can be divided into radial bimetallic thermometer, axial bimetallic thermometer and universal type of bimetallic thermometer. As we all know, as measuring instruments, due to the use after period of time, possible measurement deviation problem, cause this reason a lot of measurement deviation. So in order to ensure the precision of measurement, we require bimetallic thermometer calibration is required on a regular basis. So what the bimetallic thermometer inspection period is how long? In fact about this problem, also cannot treat as the same. Because this has to do with the reasons of errors in measurement of. If it is because we caused by improper use, personnel training, we are used to inform the correct method of use, can reduce the occurrence of deviation. But if the force majeure factors, such as double metal thermometer installed in strong shock environment for a long time, so it could be far greater than the possibility of errors occurring in installation of bimetallic thermometer in normal environment. So, according to our experience, bimetallic thermometer calibration period is 1 year, if in strong shock environment, then the test time is should be 6 months or less. This can be reference to develop according to test results for the first time.