Alcohol thermometer
The alcohol thermometer or spirit thermometer has a similar construction and theory of operation as a mercury-in-glass thermometer. However, the thermometric fluid of an alcohol thermometer is less toxic and evaporates quickly making it a safer alternative to mercury thermometers. The ethanol version is the most widely used due to the low cost and relatively low hazard posed by the liquid in case of breakage.
An
The liquid used can be pure ethanol, toluene, kerosene or isoamyl acetate, depending on manufacturer and working temperature range.[1] Since these are transparent, the liquid is made more visible by the addition of a red or blue dye. One half of the glass containing the capillary is usually enamelled white or yellow to give a background for reading the scale.
The range of usefulness of the thermometer is set by the boiling point of the liquid used. In the case of the ethanol-filled thermometer, the upper limit for measurement is 78 °C (172.4 °F), which makes it useful for measuring daytime, nighttime and body temperatures, although not for anything much hotter than these.
Ethanol-filled thermometer are used in preference to mercury for
History
The alcohol thermometer was the earliest efficient, modern-style instrument of temperature measurement. As is the case with many early, important inventions, several people are credited with the invention. These include
References
- ^ "Thermometer Filling Liquids" (PDF). Charnwood Instrumentation. Archived from the original (PDF) on 2 November 2014.
- ^ British Standard 692:1990 Specification for Meteorological Thermometers
- ^ "Archived copy" (PDF). Archived from the original (PDF) on 21 April 2015. Retrieved 4 June 2015.
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: CS1 maint: archived copy as title (link) - ISBN 0-471-89383-8page 4
- ^ Encyclopædia Britannica "Science & Technology: Daniel Gabriel Fahrenheit" [1]
- ^ Encyclopedia of World Biography "Gabriel Fahrenheit"