What is a thermometer?
Thermometers are instruments used to measure temperature and sometimes in conjunction with other equipment to control temperature. Thermometers work on different properties. Each of these properties is called a thermometer. The most important thermometric quantities are the volume or height of a liquid in a conventional thermometer, the most famous of which is the mercury thermometer in a home, the pressure of a gas. Specific in constant volume or gas volume at constant pressure in gas thermometer, electrical resistance of wire used in resistance thermometer, electric current in connecting two heterogeneous metals to each other (in thermocouple thermometer), matching light color of incandescent lamp in azometers which Pyrometers are also known as other parameters that measure temperature
Ordinary thermometer (expansion thermometer)
An expansion thermometer, commonly known as a conventional mercury thermometer, is a narrow tube with a spherical or cylindrical tank filled with a liquid, mostly mercury or alcohol. . This liquid, known as a thermometer, expands due to heat, and its surface inside the tube rises in accordance with the law of surface expansion of liquids. In these thermometers, the tank wall of the thermometer is mostly made very thin to help the heat exchange between the liquid and the outside environment and this exchange is done quickly. The narrower the thermometer tube, the thinner the tank wall, and the larger the volume of tank and liquid inside the thermometer, the more accurate the thermometer.
In this type of thermometer, some gas is in a tank with a constant volume and its pressure is constantly being measured and controlled by a barometer. As the temperature of the gas increases, its pressure directly increases. If this thermometer is properly calibrated, by measuring the pressure at any given moment, the temperature value can be obtained at that moment.
A thermocouple thermometer (from the family of contact thermometers) or in other words a thermocouple thermometer is a thermometer based on a thermoelectric phenomenon. According to this phenomenon, if we connect the two ends of heterogeneous thin conductor wires (for example, copper and iron) and connect the two ends of the wires to one milliampere, by heating the common point of connection of the two The wire is in a small electric current circuit and there is a potential difference that the amount of this current, in addition to the resistance of the circuit and the material of the wires, also depends on the temperature applied to the joint of the two.
To measure temperature more accurately, we can weld two heterogeneous metal rods from one end, then one of the end heads of the set to a constant temperature (for example, zero temperature equilibrium mixture of water and ice) and the other end head. Connected to an unknown temperature under measurement.
Pyrometer ( pyrometer )
Non-contact thermometers are used to measure temperatures beyond the temperature range of thermocouple thermometers, mainly used to measure the temperature of metal smelting furnaces. Pyrometers are called non-contact thermometers or sphygmomanometers. The simplest type of instrument is made from a special telescope, which includes a small incandescent lamp (tungsten lamp) and a red filter. To use a pyrometer, they point it at the furnace or any other object that intends to measure its temperature, and look at the object through a telescope lens. At first, the filament inside the lamp is seen in dark color on the light background of the furnace. By passing an electric current through the tungsten filament of the lamp and adjusting it by changing the potentiometer resistance, the color and brightness of the fixture match the brightness of the furnace background. To disappear.
Thermovisions (image thermometers) also use the same property to measure temperature.
Medical thermometer (clinical thermometer)
These thermometers are designed and manufactured to measure the body temperature (fever) of children and adults , which mainly include medical thermometers, including the following:
Medical mercury thermometer
These types of thermometers are contact thermometers, mainly with a temperature range from 35 ° C to 42 ° C. Thermometer by this thermometer is more accurate due to the narrower tube duct, magnification of the glass wall of the thermometer and fine grading. This thermometer measures body temperature with an accuracy of 0 0.1 ° C. Also, at the top of the tank of this type of medical thermometer, there is a narrow curve in the thermometer tube so that the mercury does not return to the tank after the thermometer is removed from the patient’s body and the thermometer fluid suddenly contracts.
Digital Oral Thermometer
Digital thermometers may be damaged by shock, heat or sunlight, so in addition to proper maintenance, it is best to periodically calibrate and compare the thermometer on a person with a mercury thermometer.
The so-called tympanic thermometer of the digital thermometer family is designed in such a way that a small piezoelectric sensor (sensor) receives infrared rays emitted from the tympanic membrane inside the ear. By placing this type of thermometer in the ear for a few seconds, the temperature of the inner ear is estimated and the body temperature is obtained. These thermometers are easy to use and very useful for children. This device can be used while the child is asleep.
Medical non-contact thermometer
Non-contact (infrared) thermometers, known as forehead thermometers, medical rifle thermometers, etc., are digital thermometers that are made in different types. Hold 1 cm in the middle of the forehead and within a few seconds, the babe announces the end of the work and the temperature can be read from the screen. For example, the medical laser thermometer model MS6518 is of this type. This digital gun thermometer is one of the thermometers with medical applications and helps doctors and specialized hospital and clinical staff in measuring patients’ temperature with very high accuracy and temperature measurement between 30 to 42 degrees Celsius.
Temperature controllers are other thermometer-dependent devices that, given their name, are clearly responsible for controlling the temperature during laboratory processes and bringing this quantity to a specific temperature, called a set point. Hanyang temperature controllers, for example, are among the most advanced of these tools. HANYOUNG AX9-4A multi-output temperature controller with inlet and outlet, a controller, digital thermostat with multi-output and input temperature with high speed sampling time (0.1 sec) and SSR alarm relay output, also with open and closed relay output, support It is a type of thermocouple inputs K, J, R, T and RTD probe: Pt100 Ω and has an analog output of 4-20 amps.
Food thermometer is another instrument that belongs to the family of thermometers and is divided into types of penetration thermometers and laser food thermometers and.. For example thermometer | BENETECH BENETECH GM1311 food penetration thermometer is one of the different types of this tool that is used for food thermometers such as meat thermometers.
Temperature logger or temperature thermograph are also among the devices that have used the thermometer feature.