Electromagnetic flowmeter, turbine flowmeter, vortex flowmeter, vapor flowmeter, ultrasonic flowmeter, metal rotor flowmeter, float level controller, ultrasonic level meter, radar level meter, magnetostrictive level meter, magnetic flip-plate level meter, input level meter and other products, at the same time, we also acted as a proxy for the Yokogawa EJA pressure transmitter, EJA differential pressure transmitter, Rosemount transmitter
Thermocouple working principle
Thermocouple is a temperature sensing element, it converts the temperature signal into a thermoelectric potential signal, through the electricalinstrumentation into the temperature of the measured medium.
Principle of operation:
Thermocouple is a temperature sensing element, it converts the temperature signal into a thermoelectric potential signal, through the electrical instrumentation into the temperature of the measured medium. The basic principle of thermocouple temperature measurement is two different components of the homogeneous conductor composed of closed loop, when the two ends of the temperature gradient exists, there will be a current through the loop, at this time between the two ends of the existence of Seebeck electromotive force - thermal electromotive force, which is known as the Seebeck effect. Two homogeneous conductors of different compositions are used as thermal electrodes, with the higher temperature end as the working end and the lower temperature end as the free end, which is usually at a constant temperature. According to the thermal electromotive force as a function of temperature, a thermocouple indexing table is made; the indexing table is obtained under the condition that the temperature of the free end is at 0 °C, and different thermocouples have different indexing tables. In the thermocouple circuit access to a third metal material, as long as the temperature of the two contacts of the material is the same, the resulting thermal potential will remain unchanged, i.e., unaffected by the access of a third metal in the circuit. Therefore, in the temperature measurement, can be connected to the measuring instrument, after the measurement of the thermoelectric potential, that is, you can know the temperature of the medium to be measured.
Commonly used in industry temperature measurement components, with the following characteristics:
① high measurement accuracy: thermocouple and the object to be measured in direct contact, without the influence of the intermediate medium.
② fast thermal response time: thermocouple temperature changes in response to sensitive.
③Measurement range: thermocouple from -40 ~ 1600 ℃ can be continuous temperature measurement.
④ Reliable performance, good mechanical strength.
⑤ Long service life, easy to install.
Types and structure:
(1) Types
There are K-type (Nichrome-Nickel-Silicon) WRN series, N-type (Nichrome-Silicon-Nickel-Silicon-Magnesium) WRM series, E-type (Nichrome-Copper-Nickel) WRE series, J-type (Iron-Copper-Nickel) WRF series, T-type (Copper-Copper-Nickel) WRC series, S-type (Pt-Rhodium 10-Platinum) WRP series, R-type (Platinum-Rhodium 13-Platinum) WRQ series, and B-type (Platinum-Rhodium 30-Platinum-Rhodium 6) WRR series, and so on.
(2) Structure form:
The basic structure is heat electrode, insulating material and protection tube; and is used in conjunction with display instrument, recording instrument or computer. In the field use according to the environment, the measured medium and other factors developed into a thermocouple suitable for a variety of environments. Thermocouple is simply divided into assembled thermocouple, armored thermocouple and special form of thermocouple; according to the use of environmental subdivisions of high temperature, wear-resistant, corrosion-resistant, high-pressure, explosion-proof, aluminum temperature measurement, circulating sulfurized bed, cement rotary kiln with thermocouples, anode roaster thermocouples, high-temperature hot-air furnaces with thermocouples, vaporization furnaces, carburization furnace, high-temperature salt-bath furnaces with thermocouples for copper, iron and molten iron, tungsten rhenium thermocouples, vacuum furnaces, oxidation-resistant thermocouples, tungsten rhenium thermocouples, vacuum furnaces, and so on. rhenium thermocouple, vacuum furnace, platinum-rhodium and so on.