It is possible to obtain errors as large as several degrees by improper immersion of a LiG thermometer. These errors generally tend to be larger with spirit-filled devices than with mercury-filled ones. It is possible to apply a correction for intentional immersion of either a total or partial immersion thermometer at a point other than that which it was designed for. Corrections cannot be made for complete-immersion thermometers that are immersed improperly.
Sometimes Being Wrong is Right To confuse the issue further, there are several test standards which call for the use of a liquid-in-glass thermometer to be used incorrectly. In these cases, it is important to use the thermometer as described in the test procedure, even if it is technically incorrect. In other words, everyone should use the device wrong in the right way. Parallax Yet another cause of error in taking measurements from LiG thermometers is due to the effects of parallax.
Parallax is a phenomenon that occurs when the thermometer is not viewed with the eyes level with top of the mercury column. Differences in the angle from which the top of the column is viewed can cause the mercury column to appear either higher or lower in the capillary than it actually is See Figure 3.
To avoid parallax, always keep your eyes at the same level as the mercury column. If a thermometer is particularly difficult to read, a magnifying glass, telescope, or similar optical device can assist in avoiding the influence of parallax on temperature measurements.
In Conclusion From bulb to expansion chamber, LiG thermometers are intricately-made devices that can produce accurate and effective temperature measurements. What a Minute… What about Calibration??? I knew you were going to ask that question. However, I cannot do the topic of thermometer calibration justice within the confines of this article. Such critical topic deserves an article all its own.
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Subscribe Unsubscribe. The Anatomy of a Liquid-in-Glass Thermometer. By Maria Knake , Laboratory Assessment Program Manager Posted: April Temperature Measurement: A Fact of Life Some of my fondest memories from childhood are of working in the kitchen with my mother—canning tomatoes, making candy apples, and baking bread.
Figure 2: Immersion Depths for LiG Thermometers Total Immersion Thermometers Total immersion thermometers are designed to read correctly when the bulb and the portion of the stem of the device filled with liquid are immersed in the medium to be measured.
Figure 3: The Effects of Parallax In Conclusion From bulb to expansion chamber, LiG thermometers are intricately-made devices that can produce accurate and effective temperature measurements.
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In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale.
Mercury thermometers can be used to determine body, liquid, and vapor temperature. Mercury thermometers are used in households, laboratory experiments, and industrial applications.
Common household uses of mercury thermometers include fever thermometers and oven, candy, and meat thermometers. Learn more about how to tell if there is mercury in your fever thermometer. Mercury thermometers may be used in many applications, including chemical experiments, water and acid baths, blood banks, ovens, and incubators.
EPA has launched an effort to reduce the use of mercury-filled non-fever thermometers used in industrial settings where suitable alternatives exist. To date, multiple ASTM standards have been updated to approve the use of mercury-free alternatives for temperature measurement. View a list of the updated ASTM standards. This is to help remove the threat of thermometer breakage and the subsequent release of mercury vapor indoors.
The Health Care Without Harm website presents information on specific state laws, resolutions and declarations. Electronic thermometer s work with an instrument called a thermistor. A thermistor changes its resistance to an electric current based on the temperature. Today, specialize d thermometers are used for a variety of purposes. A cryometer measures very low temperatures, for instance.
Cryometers are used to measure temperatures in space. Pyrometer s are used to measure very high temperatures. The steel industry uses pyrometers to measure the temperatures of iron and other metal s.
Astronomer s use infrared thermometers to measure temperatures in space, for instance. Infrared thermometer s detect infrared radiation at great distances and correlate it to a specific surface temperature. Astronomers deduce d that this very cold radiation was probably the faint remnant of the Big Bang —the expansion of the universe from a single point that began approximately Athletic trainers use pill thermometers in order to prevent and treat heat-related illnesses like heatstroke.
After being swallowed, a pill thermometer transmit s information about the body's core temperature for 18 to 30 hours. Pill thermometers use liquid crystal s to track changes in body heat and transmit radio wave s to a source outside the body, which records and displays this data.
Researchers at Harvard University have developed a nanothermometer that is able to measure temperature variations inside a single living cell. These crystals are less than 5 nanometers in length a sheet of paper is , nanometers thick and detect incredibly small fluctuation s in temperature.
Scientists are now developing nanocrystal technologies that can change cellular temperatures. These technologies may ultimately be used in medical treatments that overheat and kill cancer at the cellular level. Mercury thermometers were used by the inventors of both the Celsius Anders Celsius and Fahrenheit Daniel Gabriel Fahrenheit temperature scales.
This temperature was measured in nearby Death Valley in Big Bang. Celsius scale. Fahrenheit scale. Kelvin scale. Semiconductor nanocrystals having dimensions smaller than 10nm are called quantum dots.
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