PR1231/PR1232 Standard Platinum-10% Rhodium/Platium Thermocouple
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.
| 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 | |
| electrode | Two electrodes diameter is 0.5-0.015mm length is no less than 1000mm | |
| Requirements of the thermal electromotive forceMeasure junction temperature is at Cu point(1084.62℃）Al point(660.323℃)Zn point(419.527℃) and reference junction temperature is 0℃ | E(tCu)=10.575±0.015mVE(tAl)=5.860+0.37 [E(tCu)－10.575]±0.005mVE(tZn)=3.447+0.18 [E(tCu)－10.575]±0.005mV | |
| Stability of Thermo-electromotive force | 3μV | 5μV |
| Annual change Thermo-electromotive force at Cu point(1084.62℃） | ≦5μV | ≦10μV |
| Working Temperature Range | 300~1100℃ | |
| Insulating sleeve | Double hole porcelain tube or corundum tubeOuter diameter(3~4)mm, hole diameter(0.8~1.0)mm, length(500~550)mm | |
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 |
| JJG75-1995 | standard platinum-iridium 10-platinum thermocouples calibration specification |
| JJG141-2013 | Working precious metal thermocouples calibration specification |
| JJF1637-2017 | 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.
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.
