Many heater elements should be equipped with temperature control instruments to achieve temperature control. There are two ways to detect the temperature. One is to place the probe inside the heater tube, and the other is to place it outside heating element. We usually place the temperature control probe in the electric heater element.
Our commonly used temperature probe is also called thermocouple or thermal resistance mainly has J type and K type, what's the difference with the J type and K type thermocouple ?
1. The use of the two environment is different:
J-type thermocouple environment: J-type thermocouple can be used in vacuum, oxidation, reduction and inert atmosphere, but the positive iron oxidation faster at high temperature, so the use of temperature is limited, and can not be directly used in the sulfide atmosphere without protection at high temperature.
Type K thermocouple environment: Type K thermocouple is a kind of temperature sensor, type K thermocouple is usually used with display instrument, recording instrument and electronic regulator.
2. The characteristics difference
Characteristics of J-type thermocouple:
J-type thermocouple has the characteristics of good linearity, high thermoelectric electromotive force, high sensitivity, good stability and uniformity, low price and so on.
Characteristics of K type thermocouple:
(1) Wide measurement range. Commonly used thermocouples from -50 to +1600℃ can be measured continuously, some special thermocouples can be measured as low as -269℃ (such as ferronickel chromium), up to +2800℃ (such as tungsten-rhenium).
(2) simple structure, easy to use. Thermocouple is usually composed of two different kinds of wire, and is not limited by size and beginning, outside the protective sleeve, very convenient to use.
(3) High measurement accuracy. Because the thermocouple directly contact with the measured object, not affected by the intermediate medium.
3. The working temperature is different:
J-type thermocouple operating temperature: Fe-copper thermocouple covering measuring temperature range of -200~1200℃, but usually used temperature range of 0~750℃.
K type thermocouple working temperature: the use of temperature in 1300~1800℃, the requirement of precision is relatively high, generally choose B type thermocouple; The required precision is not high, and the atmosphere allows available tungsten-rhenium thermocouple, higher than 1800℃ generally choose tungsten-rhenium thermocouple; The use of temperature in 1000~1300℃ requirements of precision and relatively high available S type thermocouple and N type thermocouple; Below 1000℃, K type thermocouple and N type thermocouple are generally used, below 400℃, E type thermocouple is generally used; T-type thermocouple is generally used for measurement at 250℃ and negative temperature. T-type thermocouple is stable and has high accuracy at low temperature.
