Thermocouple index number how many kinds of _ instrument

Thermocouple can be divided into platinum thermocouple index number is PT10, PT100, PT500, PT1000, copper thermocouple for indexing, CU50, CU100. One of the commonly used, for - platinum resistance temperature measurement range 200 ~ 850 ℃, copper resistance measuring temperature range for - 50~150℃。 Chongqing instrument co. , LTD. , production thermocouple, thermocouple can be divided into copper, platinum thermocouple, thermocouple, resistance nickel thermocouples, etc. Thermocouple error thermocouple allowed error ( ℃) = - ( 0. 15 + 0. 002 X t | |) t- - - Actual temperature, for example: t = 0 ℃ thermocouple allow permissible error value = + 0. T = 15 ℃ 100 ℃ thermocouple permissible error value = + ( 0. 15 + 0. 002X100） =±0. What is the cause of the thermocouple thermometer error due to 35 ℃ all the instruments in use is will there is a fault, thermocouple is no exception. Thermocouple thermometer at the time of measurement error is also can appear error. ( 1) Heat transfer error. It is due to the side when the temperature is not in contact with the object to be tested fully. Did not reach thermal equilibrium and so on caused by the error, should be in accordance with the relevant specification more careful when using. ( 2) Degree of error. Standardization of thermocouple indexing table is produced by statistical analysis, yet the thermocouple used will vary because of material, manufacturing process, this creates a degree error, such as who do not tally with the nominal resistance value and the introduction of error. ( 3) Since the thermal error. In the process of this is due to the measurement of electric current flows through the thermocouple when falling in to produce the additional error caused. It is related to the current size and heat transfer medium. Our country industry with thermocouple limit current is less than 6 ma, so that we can limit the temperature error in 0. Within 1 ℃. ( 4) The error of the measuring circuit and digital display table. It is by the level of accuracy and display instrument itself line resistance. If use Cu50 type copper resistance temperature measurement, the resistance of the copper wires under prescribed conditions for 50, if measured and remote instrument for 4070 sichuan ℃, environment temperature changes at this time the two wire connection wires can bring about 2 ℃ to measure error, three-wire system connection leads to 0. The error of 1 ℃. In addition, the lead resistance, change the limits of the connection wire in also will cause error. ( 5) Other error. This means other than the above error. By blocking defective insulation, inserted depth is not enough, such as thermocouple degradation caused by the error. Thermocouple thermometer is measure a range of temperature in the industrial production, because of the temperature measurement with high accuracy, convenient automatic measurement has been widely used. Because of the thermocouple in low temperature range of thermoelectric power is small, so strict in measuring instrument, and it is suitable for low temperature measurement by thermocouple thermometer. Pt100 thermocouple when installation, the inserting depth of not less than 8 ~ 10 times of thermocouple protection tube diameter, as far as possible make Pt100 thermocouple heated part of growth. Pt100 thermocouple installed vertically, as far as possible in case of bending deformation at high temperature. Pt100 thermocouple in use in order to reduce the error produced by radiation and heat conduction, should try to make the protective casing surface and the temperature close to the measured medium, decrease the coefficient of Pt100 thermocouple protection tube of the black.