How do the commonly used visual thermometer readings?

Commonly used intuitive type has a glass rod thermometer thermometer, bimetallic thermometer, pressure type thermometer. The thermometer when use to look at the indicated temperature and environmental temperature whether conform to, if there is a error of different means, should not be used again. When the temperature is measured with a glass rod thermometer, due to the liquid have capillarity tube, when reading data for liquid column on the concave or convex corresponds to the scale for reading. For bimetallic thermometer and pressure thermometer read data should be in the line of sight of observer vertical alignment needle tip scale value. Due to the temperature of the glass rod thermometer general detection range within 200 ℃, bimetallic thermometer and pressure and the temperature of the thermometer is usually higher, the temperature of the analyte in the unclear how high, in order to protect the thermometer is not damaged, before buying a thermometer, be sure to have to know the temperature range of the measured medium, so buy suitable thermometer.