ASTM International Standard Specification for Thermocouple Materials, Platinum-Rhodium Alloys, and Platinum ASTM E1159-98(2003)

This specification covers non-insulated platinum rhodium alloys (weight percent composition), and platinum thermoelements. The purity of platinum for use in the negative thermo element of Type R and Type S thermocouples shall be of a specific Grade, as specified. The purity of platinum before alloying for use in the positive thermo element of Type R, S, and both thermo elements of Type B shall also be of a certain grade, as specified. All material to be supplied shall consist of continuous lengths which shall be free of kinks and shall be round and smooth. Any pits or dents that exceed a certain percentage of the diameter shall be cause for rejection of the material. After material has been processed to its final diameter and prior to subsequent anneal, it shall be cleaned to remove all dirt, lubricant, fingerprints, or other foreign residue. The thermo elements shall be such that, when matched as a thermocouple, the EMF output shall meet the tolerance on the initial value of EMF versus temperature as specified.