... 4.MAIN CHARACTERISTICS OF OUR THERMOCOUPLE ALLOYS TYPE J (Iron vs Constantan) is used in vacuum, ... recommended for longer life at these temperatures. TYPE K (CHROMEL vs ALUMEL ) is used in oxidizing ... , developed to improve the drawbacks that type K thermocouple has. The main chemical composition of ... be used in the similar atmospheres that type K works, and the operating temperature range is - ...