Transformation of energy

Instruments for measuring temperature, types and characteristics

Instruments for measuring temperature, types and characteristics

There is practically no other value in measurement technology that is measured as frequently as temperature. However, this measurement parameter can only be objectively determined if you have a suitable measuring instrument for the respective application.

The unit of temperature in the International System of Units is the kelvin, although some instruments also express temperature in degrees Celsius, or Fahrenheit.

Some temperature sensors are very sensitive and display the measurement results through a digital display.

1.- Infrared thermometers

Infrared thermometers measure temperature safely and accurately from a distance, without contact.

An infrared thermometer, or as it is also called, a pyrometer is a device for non-contact measurement of the temperature of bodies. This instrument for measuring temperature measures the power of the thermal radiation of the object to be measured, mainly in the infrared and visible light ranges.

Pyrometers are used to measure the temperature of objects that, for safety, require a certain distance to be maintained.

2.- Surface temperature meters

Surface temperature probes are especially suitable for measuring surface temperatures on different bodies.

This measurement may be necessary in various industrial processes, for example to monitor the wall temperature of furnaces or pipes.

Surface temperature meters are also used for medical purposes. This type of thermometer is the one used to take body temperature.

3.- Instruments to measure air temperature

Air temperature gauges are instruments for measuring ambient temperature.

A typical air temperature meter is the mercury thermometer, especially in meteorology. Mercury expands as a function of temperature. Mercury sits inside a glass tube and when it expands, the mercury rises up the tube. As we know the coefficient of expansion of the material mercury, we can measure the change in temperature by measuring the height to which it has risen inside the tube.

In meteorology it is common to use a maximum and minimum thermometer in which the maximum and minimum temperature of a day is recorded.

4.- Penetration thermometers

The penetration thermometer allows to measure the temperature in solid or semi-solid substances.

This type of instrument is commonly used in the kitchen during food preparation. In this way, we can know the temperature inside a food during cooking.

These types of thermometers are designed for measurements in liquids and viscoelastic media (dough, meat, fish, etc.).

Penetration thermometers are also used to measure air temperature. For this, it is necessary for the probe to be in contact with the environment long enough to adapt to room temperature.

In addition, they can be used as an immersion thermometer.

5.- Immersion thermometers

Immersion thermometers are designed to measure the temperature in liquids and viscoelastic substances with a tip designed for piercing. It can also be used on aggressive substances.

It can be installed in the heating system of private residential houses, cottages, townhouses, bathrooms, as well as in hot water supply systems.

Immersion thermometers consist of the thermometer itself and a sleeve that fits over it. The thermometer reads the readings using a special plate, which is made of two different metals. When the temperature of the liquid begins to change, this plate, due to its linear expansion, begins to bend in one direction or another and pulls the indicator of the thermometer scale behind it, to which it is attached.

6.- Thermometric strips

Thermometric strips are an economical alternative to the thermometer.

Strip thermometers are made of self-adhesive sheets. These sheets are composed of thermosensitive elements for the regulation and control of temperature.

They are used to measure the temperature in small or mobile elements and to be able to monitor the long-term results.

These strips change color irreversibly after one second.

7.- Thermographic cameras

Thermal imaging cameras are a very versatile measuring instrument. Typically, this type of camera is used for maintenance, security and alarm systems, building and heating systems.

In the construction of a building these cameras help to locate thermal bridges in the insulators. They also allow to detect problems in the structure of the building.

When using this instrument in heating systems, it is possible to verify the proper functioning of the air conditioning, find cold spots or find leaks in the pipes.

8.- Digital thermometers

These types of thermometers allow accurate display of readings.

Thanks to their large display, digital thermometers are extremely practical for daily temperature measurement.

Publication Date: August 26, 2021
Last Revision: August 25, 2021