A dry bulb temperature thermometer works by measuring the heat-related movements of the molecules in a thermometer bulb.
A dry bulb temperature thermometer is a device that measures the temperature of the environment.
The most common type of dry bulb thermometer is the mercury-in-glass thermometer, which comprises a glass tube containing mercury and a constriction at its base where the mercury level can be observed.
Dew point temperature, wet bulb temperature or wet bulb temperatures, relative humidity, air temperature, wet bulb globe temperature can be measured by this thermometer.
Constant wet bulb temperatures, ambient air temperature, dew point can also be measured by dry bulb thermometers.A typical dry bulb thermometer works by measuring changes in thermal expansion around the current room temperature, as those changes represent heat given off from nearby objects. As an object's temperature increases, so does its volume due to increasing atomic activity on the molecular scale. This increase in volume causes an upward movement of the column of mercury or alcohol inside of a glass-based thermometer such as that found in household thermostats.
Mercury is an element that has a high coefficient of expansion and it also has relatively low boiling and freezing points. A typical household mercury-in-glass thermometer works by measuring how much two pieces of metal expand when heated or cooled to determine the change in their length when exposed to different temperatures. The sign of the temperature is determined by moving a wetted index pointer over a calibrated scale. The device measures temperature by determining how much the volume has changed from its original size, as mercury atoms expand rapidly as they change from a solid to a liquid and then to vapour at room temperature.
In areas with high relative humidity or moisture content in the air, this can cause inaccuracies when using a dry bulb thermometer since water molecules take up space and reduce thermal expansion.
A typical household mercury-in-glass thermometer consists of a glass tube containing mercury, with a constriction at its base where the level can be observed. The device also has an index pointer and a calibrated scale to indicate readings in degrees Celsius or Fahrenheit.
A wet-bulb thermometer is a device that also measures the humidity and temperature of the air. A wet bulb thermometer works by measuring how much water vapour is in the air, which changes with atmospheric conditions such as pressure and temperature.
A typical household wet-bulb thermometer is a glass tube containing a rotating wheel. The rotating wheel has a cloth wick at one end that can absorb water from an enclosed reservoir of liquid, and during evaporation, the wheel rotates to indicate the current humidity with markings on its surface.
A clinical thermometer, also known as a medical thermometer, is used to measure body temperature. It consists of a glass tube containing mercury or alcohol which expands at different rates due to heat and has markings indicating temperatures in degrees Celsius or Fahrenheit.
An infrared thermometer measures surface temperatures by detecting the infrared radiation emitted by the object being measured. This method does not require contact with the skin so it can be performed several inches away from patients during examinations.
Digital electronic-type clinical thermometers are sensitive enough to measure temperatures in neonatal infants using disposable plastic probe covers, while some devices can even take readings inside your mouth without needing to touch your skin. There are also infrared ear canal thermometers that use optical detectors placed within each ear canal. Your air conditioner may have a thermometer built-in to automatically regulate temperature.A digital electronic type clinical thermometer is similar to the standard mercury-in-glass thermometers used in homes. It consists of a probe that contains electronic circuitry and an attached probe cover that functions as the sensing element. The device works by converting temperature into an electrical signal that can be displayed on an LCD screen or sent to a computer, printer or other display devices using either radio waves or cable connection. Digital thermometers are now so fast that they can take readings within seconds without any discomfort for patients, especially infants who do not like having their temperature taken.
The cost of a mercury-in-glass thermometer depends on which brand is chosen, as well as the specific features you would like. Prices may start from around $8 and may range up to $80 or more for the top of the range models with simple digital displays and advanced functions such as memory recall. Generally speaking, mercury-in-glass thermometers are very durable so they usually last many years with proper care.
In Australia, most types of mercury in glass thermometers are designed for oral use only. To take a temperature reading, shake down the thermometer then clean with soap and warm water. Rinse under lukewarm tap water then wipe dry with a tissue or paper towel before placing into the patient's mouth at least one inch under the tongue.
You should never use a clinical mercury-in-glass thermometer to take an ear measurement as this can cause serious damage to the eardrum if too much pressure is used. Instead, opt for an infrared tympanic membrane thermometer that uses a bright red light beam that is placed in each ear canal without ever touching the sensitive skin inside of your baby's ears. Always read manufacturer instructions carefully before using any type of clinical thermometer on infants or children as some require special care during use to prevent the spread of infection. And make sure filters in your air conditioning system are regularly cleaned.For more information on the different types of thermometer, take a look at Health Direct.