As shown in Table I, there are seven thermocouple standards applicable to heat treating furnaces. These include Reference Standard, Primary Standard, Secondary Standard, Temperature Uniformity Test Standard, System Accuracy Test plus Working and Load Standards. This chart summarizes the type of thermocouples which can be used for each category in addition to calibration frequency and accuracy requirements. These standards were established by SAE (Society of Automotive Engineers) specification SAE-AMS-2750 Rev. C in 1990. This specification has been adopted by the U.S. Department of Defense. It is a valuable reference and we suggest that anyone who manufactures or uses heat treating furnaces should have a copy of this specification in their Quality Control Department.
|Outline of Sensors|
|Nomenclature||Description||Calibration||Use/Max Error Limit|
|Period||Against||Correction Factor (°F)|
|Reference Standard||Platinum Platinum-Rhodium||5 years||NIST Reference Standard||Primary Standard Calibration None|
|Primary Standard||Platinum Platinum-Rhodium||3 years||Reference Standard||Secondary Standard Calibration ±2.7° or ±0.25%**|
|Secondary Standard||Base or noble metal||1 year base 2 years noble||Primary Standard||Test Sensor Calibration base: ±2° or ±0.4%** noble: ±2.7° or ±0.25%**|
|Temperature Uniformity Test||Base of noble metal||3 months base 6 months noble||Primary or Secondary Standard||Temperature Uniformity Tests ±4° or ±0.75%**|
|System Accuracy Test||Base of noble metal||3 months base 6 months noble||Primary or Secondary Standard||System Accuracy Tests ±2° or ±0.4%**|
|Working||Base of noble metal||Before installation||Primary or Secondary Standard||Installation in Equipment Class 1: ±2° or ±0.4%** Class 2: ±4° or ±0.75%**|
|Load||Base of noble metal||3 months N, R, S 6 months other||Primary or Secondary Standard||Insertion in Loads ±4° or ±0.75%**|
|* Sensors of Equivalent or Greater Accuracy are Acceptable|
** Percent of Reading, if Greater Than Correction Factor in Degrees
|Aerospace Material Specification - SAE AMS-2750 Rev. C. issued 1980-04-15, Revised 1990-04-01|
Superceding AMS-2750B. Society of Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, PA 15096 (1990).
Nanmac's calibration laboratory will calibrate bare or insulated thermocouple wire, assembled thermocouples, RTD's, hermistors and instruments. All of our calibration equipment is calibrated against National Institute of Standards and Technology (NIST) standards. Our calibration data are traceable to NIST standards. Calibration costs are listed in the chart below. The maximum temperature range of our standard services is 2,100 degrees Fahrenheit.
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