Temperature Measuring Devices

In this article I am discussing temperature, temperature measurement and temperature measuring devices such as thermometers, thermocouples, resistance thermometers, infrared sensors, bimetallic devices, change-of-state sensors, silicon diodes.

Temperature

Temperature is an objective measure of how hot or cold an object is. It can be measured with a thermometer or calorimeter. It is a means of determining the internal energy contained in a system. The units of temperature are Celsius (°C), Kelvin (K) and Fahrenheit (°F). 

Temperature measurement

Temperature is the unit used to measure the heat of any body Temperature indicates whether a body is hot or cold. Celsius (°C), Kelvin (K) and Fahrenheit (°F) are the SI units for measuring temperature. Devices used to measure temperature are thermometers, thermocouples, resistive temperature measuring devices, infrared sensors, bimetallic devices, change-of-state sensors, silicon diodes.

Conversion from of temperature units

• One Fahrenheit (°F) is (°F - 32) / 1.8 Celsius (°C) and (°F - 32) / 1.8 + 273.15 Kelvin (K)
• One Celsius (°C) is (°C * 1.8) + 32 Fahrenheit (°F) and °C + 273.15 Kelvin (K)
• One Kelvin (K) is (K - 273.15) * 1.8 + 32 Fahrenheit (°F) and K - 273.15 Celsius (°C)

Devices used to measure temperature 

• Thermometers
• Thermocouples
• Resistance Temperature Detector
• Infrared Sensors
• Bimetallic Devices
• Change-of-state Sensors
• Silicon Diodes

Thermometers

Thermometer is a well-known liquid expansion devices it is  also used for temperature measurement. Thermometer is come in two main classifications first is mercury type and Second is organic, usually red, liquid type. A thermometer measures temperature and temperature gradients. A temperature gradient is the degree to which an object is hot or cold. Thermometers are available in many forms such as digital thermometers, ear thermometers or tympanic thermometers, infrared thermometers, strip type thermometers and mercury thermometers.

Thermocouples

Thermocouples are voltage devices that show a temperature measurement with a change in voltage. When the temperature increases, the output voltage of the thermocouple increases. Often the thermocouple is enclosed within a metal or ceramic shield that protects it from exposure to various environments. For trouble-free use in acid and strong caustic solutions, metal-clad thermocouples are available with a variety of outer coatings such as Teflon.

Common thermocouples are Type E, Type C, Type J, Type K, Type N, Type T, Type S, Type R and Type B.

Resistance Temperature Detector

Resistance temperature detector is also known as RTD. An RTD is a temperature measuring device that measures temperature when resistance changes. RTD works on temperature and resistance relationship and RTD is a passive device. There are two types of RTDs one is a thin film element and the other is a wire wound element.

Infrared Sensors

Infrared sensors are also known as IR temperature sensors and infrared sensors are non-contact sensors. Infrared sensor is also known as IR temperature sensor. For example, if you hold a typical infrared sensor in front of your desk without touching it, the sensor will tell you the temperature of the desk based on its radiation. An infrared temperature sensor measures temperature using infrared energy. An infrared temperature sensor emits infrared energy and measures temperature

Bimetallic Devices

Bimetallic devices take advantage of the metal's expansion when heated. In these devices, two metals are bonded together and mechanically connected to the pointer. A bimetallic device causes one side of the bimetallic strip to expand more than the other when heated. And when the pointer is properly formed, the temperature measurement is indicated.

Change-of-state Sensors

Change-of-state temperature sensors measure the change in state of a material due to a change in temperature, such as the change from ice to water and then to steam. Change-of-state sensors include tablets, labels, crayons, liquids, and lacquer crystals that change shape after reaching a certain temperature.

Silicon Diodes

A silicon diode sensor is also known as a silicon pn junction diode sensor and is used to measure temperature. A silicon diode sensor has a higher accuracy for measuring temperature than other temperature measuring devices. And the silicon diode sensor is a device specifically developed for the cryogenic temperature range. A silicon diode sensor is an electrical sensor