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PR1231/PR1232 Standard Platinum-10% Rhodium/Platium Thermocouple

PR1231/PR1232 Standard Platinum-10% Rhodium/Platium ThermocouplePart1 OverviewThe first and second grade standard platinum-iridium 10-platinum thermocouples which have high accuracy good physical...

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PR1231/PR1232 Standard Platinum-10% Rhodium/Platium Thermocouple

Part1 Overview

The first and second grade standard platinum-iridium 10-platinum thermocouples which have high accuracy good physical and chemical properties, good oxidation resistance at high temperatures,  good stability and reproducibility of thermoelectromotive force. Therefore, it is used as a standard measuring instrument in (419.527~1084.62) °C , it is also used to temperature magnitude transmit  and precision temperature measure in the temperature range.

Part2 Technical parameters

Parameter   index

First   grade platinum-iridium 10-platinum thermocouples

Second   grade platinum-iridium 10-platinum thermocouples

Positive   and negative

The   positive is a platinum-rhodium alloy (platinum 90% rhodium 10%), the negative   is pure platinum


Two   electrodes diameter is 0.5-0.015mm length   is no less than 1000mm

Requirements   of the thermal electromotive force

Measure   junction temperature is at Cu point(1084.62℃Al point(660.323℃)

Zn   point(419.527℃) and reference junction temperature is 0℃


    E(tAl)=5.860+0.37 [E(tCu)-10.575]±0.005mV

E(tZn)=3.447+0.18 [E(tCu)-10.575]±0.005mV

Stability   of Thermo-electromotive force



Annual   change Thermo-electromotive force at Cu point(1084.62℃



Working   Temperature Range


Insulating   sleeve

Double   hole porcelain tube or corundum tube

Outer   diameter(3~4)mm, hole diameter(0.8~1.0)mm, length(500~550)mm


Part3 Application Instructions

standard platinum-iridium 10-platinum thermocouples must be in accordance with the national delivery system table,National verification procedures must be implemented. First grade standard platinum-iridium 10-platinum thermocouples can be used to measure second grade,Ⅰ grade,Ⅱ grade platinum-iridium 10-platinum thermocouples and Ⅰ grade base metal thermocouples; Second grade platinum-iridium 10-platinum thermocouples can only used to measure Ⅱ grade base metal thermocouples

National verification code

National verification name


standard platinum-iridium   10-platinum thermocouples calibration specification


Working precious metal   thermocouples calibration specification


base metal thermocouple   calibration specification



Part4 Maintenance and preservation

1. The standard thermocouple calibration period is 1 year, and every year the standard thermocouple must be calibrated by metrology department.

2. The necessary supervisory calibration should be performed according to the usage.

3. The work environment of the standard thermocouple should be clean to avoid contamination of the standard thermocouple.

4. The standard thermocouple should be placed in a non-polluting condition and protected from mechanical stress.

Part5 Precautions when use

1. The insulation tube cannot be used at high temperature roasting. The original insulation tube is used after strict cleaning and high temperature roasting.

2. The insulation tube ignores positive and negative, which will cause the platinum pole to be contaminated and the thermoelectric potential value to decrease.

3. Randomly the standard thermocouple insulation tube with cheap wire will contaminate the standard thermocouple, and the protective metal tube must be used for the verification of the base metal thermocouple.

4. The standard thermocouple cannot be suddenly placed in the temperature-regulating furnace, nor be taken out from the temperature-regulating furnace. The sudden-heat and cold will affect the thermoelectric performance

5.Under normal circumstances, the verification furnace for the precious metal thermocouple and the base metal thermocouple should be strictly distinguished; if it is impossible, the clean ceramic tube or corundum tube(diameter about 15mm) should be inserted to the furnace tube for protecting precious metal Thermocouples and standard thermocouples from base metal thermocouple pollution.


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Changsha Panran Technology Co., Ltd.

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