Correct selection method of thermocouple

In traditional industrial applications, thermocouple elements are generally terminated on connectors; However, reference connection points are rarely located on connectors. Instead, switch to a controlled environment with a relatively stable temperature using a suitable thermocouple extension cord. The selection of thermocouple should be based on the use of temperature scale, the required accuracy, the use of atmosphere, the determination of the function of the target, echo time and economic benefits and other comprehensive consideration.

1. Selection of measurement accuracy and temperature measurement scale

When the temperature is between 1300 and 1800℃ and the accuracy is relatively high, type B thermocouple is generally used; The accuracy is not high, the atmosphere allows the use of tungsten-rhenium thermocouple, higher than 1800℃ generally choose tungsten-rhenium thermocouple; Using temperature in 1000~1300℃ requires high accuracy and high availability of S-type thermocouple and N-type thermocouple; K type and N type thermocouple are generally used below 1000℃, and E type thermocouple is generally used below 400℃; At 250℃ and negative temperature measurement generally use T type thermocouple, T type thermocouple stability and high precision at low temperature.

2, use the selection of atmosphere

S type, B type, K type thermocouple suitable for strong oxidation and weak recovery atmosphere, J type and T type thermocouple suitable for weak oxidation and recovery atmosphere, if the use of better air tightness protection tube, the requirements of the atmosphere is not too strict.

3. Selection of durability and thermal echo

The thermocouple with large wire diameter has good durability, but the response is slower. For the thermocouple with large heat capacity, the response is slow. When measuring the temperature with large gradient, the temperature control is poor under the condition of temperature control. Request echo time fast and require a certain durability, select armoring pair is more suitable.

4, measure the nature of the target and the state of the thermocouple selection

The temperature measurement of moving objects, oscillating objects and high pressure vessels requires high mechanical strength; the atmosphere with chemical pollution requires protective tubes; and the insulation is relatively high in the case of electrical interference.

Summary, trust after reading the above content, we have a beginning of the thermocouple understanding, together also expect you in the learning process, do a good summary, so as to continuously improve their professional level.