Type K-Chromel Nickel Chromium Alloy, Alumel Nickel-Aluminium Alloy.
This is the most commomly used general purpose thermocouples. They are available in the -200°C to +1200°C range. The characteristic of the thermocouple undergoes a step change when a magnetic material reaches its Curie point. This occurs for this thermocouple at 352°C. Sensitivity is 41µV/°C. Type K and N are the most oxidation resistant base metal thermocouples. Not recommended for temperature of 1200C for long period.

Type J-Iron, Constantan
Limited range -40 to +750°C makes type J less popular than type K. The main application is with old equipment that cannot accept modern thermocouples. J types cannot be used above 760°C as an abrupt magnetic transformation causes permanent decalibration. The magnetic properties also prevent use in some applications. Type J's have a sensitivity of 53µV/°C. Not recommended for temperature higher than 480C because of the higher oxidation rate of the iron element.

Sensors can be easily combined with temperature meters, controllers and a complete line of accessories including connectors, transmitters and extension wires to deliver robust solutions for a wide range of temperature measurement and control requirements.