Thermocouples conversion table

In industry or medical, many processes require the use of a thermostat to perform temperature measurements. The robust thermocouple sensor, usable on large temperature beaches and offering a short response time, is an excellent solution. It works thanks to the electrical voltage generated by the temperature difference between two parts of the probe. The conversion table is an interpretation tool for this tension which is also used to calibrate the measurement probe.

What is a thermocouple table?

A thermocouple table or table is an essential tool for the use of Thermocouple temperature sensor. The table allows Convert an electro-motor force (FEM), raised thanks to a measurement device, in a temperature in degrees Celsius or in degrees fahrenheit. This conversion is done thanks to the Seebeck coefficient, a variable specific to the nature of the materials constituting the sensor. Indeed, Thermo electric sensitivity varies from one metal to another. It is often the recorder, the case measuring the tension, which converts directly into temperature. However, it is useful to understand how the thermocouple probe works to use it as well as possible.

The thermocouple table is also used to Make the calibration of the thermal probe sensor. The calibration of a thermocouple follows the recommendations of the ASTM (American Society for Testing and Materials) which aims to standardize this type of procedure. During calibration, we make sure that the voltage obtained by exposing the thermocouple to a given temperature corresponds well to the expected temperature in the table. We repeat the operation several times, in order to test thermocouple On several temperatures of its measurement range. In the event of inaccuracy of the statements, a correction coefficient is applied when using the temperature probe.

How to read a thermocouple conversion board?

The thermocouple conversion board can take several forms. It indicates the degrees Celsius or Fahrenheit corresponding to each voltage power in Millivolt (MV). When this voltage/temperature ratio is in the form of Thermocouples curves, we see that this report is not linear and that the shape of the curve varies between the types of thermocouples. To read the table, You have to know the type of thermocouple. The most detailed conversion tables indicate all possible degrees for a type of thermocouple. Other more synthetic paintings compare the voltage of all types for each ten degrees. You can consult a summary of thermocouple summarized on our site by going to the page Thermocouple conversion table.

The type of thermocouple Varies depending on the nature of the materials used to design it. Even if it is possible to create a thermocouple from many metal combinations, 8 main types are generally used. They are supervised by a European standard and make it possible to cover various applications. Thermocouples of types E, J, K, N and T are made up of common metals such as iron, constantan, copper, alumel or chromel. Types B, R and S are made from noble metals, such as platinum, which makes them quite expensive. Each material has its own expansion and conductivity characteristics. Types N, S, B and R have the particularity of being able to measure high temperatures, up to 1,800 ° C in maximum temperature. Each type of thermocouple has a temperature range optimal.

How to know the potential difference of a thermocouple?

The thermocouple works thanks to The tension that appears when the two types of sensor welds are exposed to different temperatures. The two conductive metals wires are linked together at the hottk, or hot welding. This is the part exposed to the middle in which a temperature control is carried out. The cold point is the welding that is at the other end of the wires, on the side of the measurement instrument. You should know that The thermocouple table is based on the tension noted when the cold weld is at 0 ° C. To know the potential difference precisely, it is therefore necessary to be interested in the compensation method of the cold point.

One of the solutions is simply Maintain cold welding at 0 ° C. The method is then to immerse it in a cold water bath. Cooling is a reliable technique, but which can be difficult to put in place concretely in certain areas. It can indeed be implemented in a laboratory. In an industrial context, where a large number of thermocouples can be used simultaneously, the method is more restrictive. A second method consists of Measure the temperature of the cold point in real time. While following the variations in room temperature. It is then necessary to convert this temperature into millivolts and carry out a differential calculation to obtain the difference in real potential.

At Thermometre.fr, we offer a wide range of measurement probe to be as close as possible to the expectations of professionals. Contact your advisor To be oriented towards the equipment most suited to your project.