Thermometer At A Glance

By Author: Robin son
Total Articles: 4
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What is a thermometer?
Thermometer has been derived from a Greek word. Therm means warm and meter means to measure. The device is used to measure temperature or temperature gradient. The temperature has two major elements. The temperature sensor, in which some physical changes occur, and the further the physical gets converted to some value. Thermometers usually use electronic method to display results.
Types of Thermometers - Measurement Units

Celsius and Fahrenheit Thermometers
The Celsius thermometers use the Celsius as the measurement unit and Fahrenheit thermometers use Fahrenheit as the temperature measurement unit. Some thermometers have the measuring scales for both Celsius and Fahrenheit. These thermometers also termed temperature measuring instruments give the reading in Celsius as well as Fahrenheit. These thermometers can also be termed as Temperature measuring Instruments
Laboratory thermometers
Laboratory thermometers can be further classified into general Purpose thermometer, precision thermometer, minus range thermometer, oven or long stem thermometer, I.P thermometer, A.S.T.M ...
... thermometer, S.T.P.T.C thermometer, standard joint thermometer and high precision thermometer.
Industrial thermometers
Industrial thermometer can be classified into inclusion type/enclosed scale type thermometer, pocket thermometer, refrigeration thermometer, V-type metal encased Engine /pipe/tank thermometer, wall thermometer, soil thermometer, rail thermometer, Electric contact thermometer, Shake- Down type thermometer, Sugar Boiling thermometer, cold storage thermometer, Tank dipping thermometer, Wire cage thermometer.
Meteorological Thermometer
Meteorological Thermometer can also be classified into Hygrometer and whirling hygrometer.
Precision, Accuracy, and Reproducibility
The "Boyce Moto Meter" radiator cap on a 1913 Car-Nation automobile, used to measure temperature of vapour in 1910s and 1920s cars. The precision or resolution of a thermometer is simply to what fraction of a degree it is possible to make a reading. For high temperature work it may only be possible to measure to the nearest 10°C or more. Clinical thermometers and many electronic thermometers are usually readable to 0.1°C. Special instruments can give readings to one thousandth of a degree. However, this precision does not mean the reading is true.
Thermometers which are calibrated to known fixed points (e.g. 0 and 100°C) will be accurate (i.e. will give a true reading) at that point. Most thermometers are originally calibrated to a constant-volume gas thermometer.[citation needed] In between a process of interpolation is used, generally a linear one. This may give significant differences between different types of thermometer at points far away from the fixed points. For example the expansion of mercury in a glass thermometer is slightly different from the change in resistance of a platinum resistance of the thermometer, so these will disagree slightly at around 50°C.There may be other causes due to imperfections in the instrument, e.g. in a liquid-in-glass thermometer if the capillary varies in diameter.
For many purposes reproducibility is important. That is, does the same thermometer give the same reading for the same temperature (or do replacement or multiple thermometers give the same reading)? Reproducible temperature measurement means that comparisons are valid in scientific experiments and industrial processes are consistent. Thus if the same type of thermometer is calibrated in the same way its readings will be valid even if it is slightly inaccurate compared to the absolute scale.
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