Chromel-constantan thermocouples, temperature range

The operating temperature range is typically 100 -1000 K using samples of area 30-50 mm and thickness 0.01-0.3 mm. The temperature resolution is 0.0025 K for T< 770 K and 0.025 K for r> 770 K. The sample holder is purged with a dry inert gas. Alumel-chromel or chromel-constantan thermocouples of 0.002 mm diameter are placed in a paper frame and soldered to metal samples to measure. Polymers are dissolved in an organic solvent and the solution is spread on a thin metal... 

Thermopower measurements used the differential technique [48,49] two isolated copper blocks were alternately heated with the sample mounted between the copper blocks with pressure contacts. The heating current was accurately controlled by computer. The temperature difference between the two copper blocks was measured by a chromel-constantan thermocouple and did not exceed 0.5 K for each thermal cycle. The voltage difference across the sample was averaged for one complete cycle. Any temperature difference between sample and thermocouple was less than 10% of the temperature gradient across the sample the thermometry was carefully calibrated for the entire temperature range (5 K < T < 300 K). The absolute thermopower of the sample was obtained from the absolute scale for lead [48,49]. 

Temperature measurements ranging from 760 to 1760°C are made usiag iron—constantan or chromel—alumel thermocouples and optical or surface pyrometers. Temperature measuriag devices are placed ia multiple locations and protected to allow replacement without iaciaerator shutdown (see... 

This instrument utilises a silver block chamber with an external heater. The chamber contains a constantan disc with raised platforms for the sample and reference containers. The temperature difference between sample and reference is monitored by area thermocouples formed by the constantan disc and chromel wafers under the platforms. Amplification and electronic compensation of the differential temperature signal provides a linear calorimetric response over a wide temperature range. The theory of this instrument is discussed by Lee and Levy 6). Other available examples of... 

Thermocouples are based on the thermoelectric Seebeck effect, which generates a voltage at the junction between two metallic conductors, which depends on temperature [13]. Thus, in the measuring circuit, two junctions are created, namely, a sensitive (or hot) junction at the point where temperature has to be measured and a nonsensitive (cold) junction, kept at a constant known temperature, where the voltage established between the conductors can be easily measured [19]. Different typologies of thermocouples exist for application in a wide range of conditions they essentially differ by the materials, the most common being J (iron/constantan), K (chromel/alumel), T (copper/constantan), and E (chromel/constantan). 

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