Thermometers

A thermometer is any device designed to capture temperature variations in the medium and express it through measurements that we can read, either by displaying a number on a screen, capturing different colors in images, observing an increase in the volume of a liquid, etc.

Industrial thermometersare very different from those in the clinical world. Here they are much more complex instruments since they must detect much higher (or lower) temperatures than the previous ones.

Gas thermometers

Gas thermometersare instruments so precise and complex that their use is limited to the calibration of other s thermometers. That is, it is admitted that the gas ones always give the correct information, so if another thermometer (for example, a digital one) gives a temperature reading different from yours, it is because the latter is poorly manufactured.

In this case, the gas thermometer consists of an apparatus inside which there is a gas, usually nitrogen. When exposed to a body with a certain temperature, the pressure inside it will vary according to this temperature. The higher the temperature, the more pressure. Then, from this variation in internal pressure, the temperature can be calculated.

In addition to being the most accurate, they are also the ones that detect a greater temperature range: from - 268 °C to more than 530 °C. But, of course, their use is very complex and, in fact, it is no longer that they are not used domestically, but only very specific industries where they need to frequently calibrate their thermal equipment will have them.

Thermometers with bimetallic sheet

Bimetallic sheet thermometersare, like mercury thermometers, mechanical devices, because there are industries that defend that they work better since there is no risk that electronic devices fail, because they do not have. In this case, however, no toxic liquid comes into play.

They are also based on the expansion of an element depending on the temperature to which it is exposed, but in those of bimetallic sheet, what expands is not mercury, but a solid metal. This "robust" nature makes it the preferred option in all types of industries when you want to know the temperature especially of toxic liquids at very high temperatures, as it offers surprisingly accurate measurements up to 600 ° C.

Resistance thermometers

Resistance thermometersare based on the properties of platinum and other materials such as copper or tungsten whose resistance to electricity varies depending on the temperature to which they are exposed.

Resistance thermometersare generally made of platinum, as it is the one that works best to relate variation of electrical resistance and temperature. They are used only in industries since they are expensive and the measurement they make is very slow, although they allow to detect subtle variations up to temperatures of more than 3,500 ° C, so they are very useful to know, for example, the temperature inside industrial furnaces.

Thermocouple

Thermal torque thermometersor thermocouples are very useful instruments especially in the field of laboratories, as they offer very fast measurements (less than 5 seconds) and very precisely. They consist of an instrument with two metal threads that are joined by their ends. At the point where they meet is where you come into contact with the object whose temperature you want to measure.

When this happens, the ends of these metals heat up, which results in a change in electrical resistance proportional to the temperature of the body being measured. Although they are not intended to capture body temperature, they can be used in the domestic environment, as they are not very expensive and allow you to quickly know the temperature of inanimate objects.

Pyrometers

Pyrometers are all those thermometersintended to measure more or less accurately the temperature of bodies that are more than 2,000 ° C, so they are useful in industries where foundries and other processes are carried out where you have to reach very high temperatures to ensure their correct operation.

In this sense, the aforementioned infrared thermometerscan be used, although there are also others based on the optical properties of objects or on the photoelectric phenomenon (release of electrons from a material when thermal radiation hits them).

Wet bulb thermometer

The wet bulb thermometer is very useful since, in addition to measuring temperature, it takes into account the role that humidity plays in the experimentation of it. That is, they allow us to know what the true "thermal sensation" is.

The temperature measuring tip of this instrument is covered by a textile material that is soaked by capillarity depending on the humidity outside. By taking the measurement that is given when it is wet and the one that is obtained before putting the textile material, it can be determined what the true thermal sensation is.