Polyimide-Insulated T2 Thermocouple Wire (Ni95-(Al+Mn+Si)5)

This product is Alumel (Ni95/Al-Mn-Si) thermocouple wire with polyimide insulation, supplied in continuous spooled form as the − leg of Type K thermocouple assemblies. The insulation provides electrical isolation between the two legs of the thermocouple and between the conductor and any conductive surface it contacts, allowing the wire to be routed through an assembly without additional sleeving. The polyimide insulation has a continuous service temperature of approximately 315 °C, which sets the maximum temperature at which the lead wire itself can operate — independently of the hot junction temperature, which may be significantly higher.

Alumel (Ni95/Al-Mn-Si) is the − leg in Type K thermocouple assemblies. This insulated version provides the same thermoelectric leg as the bare wire version, with the polyimide outer insulation serving as an integral electrical isolation layer for the lead section of the thermocouple assembly.

Polyimide extends the lead wire's continuous service temperature to approximately 315 °C and provides radiation resistance and chemical stability that polyester and polyurethane cannot match. For Type K thermocouple assemblies in aerospace propulsion test rigs, metallurgical furnaces, vacuum ovens, and cryogenic instruments, polyimide-insulated T2 wire ensures the negative leg lead maintains its electrical integrity under conditions that would degrade lower-rated insulation materials.

Polyimide-insulated T2 (Alumel) wire is used as the negative leg in Type K thermocouple assemblies for aerospace engine and propulsion monitoring, metallurgical furnace temperature profiling, vacuum oven thermometry, nuclear plant instrumentation, and cryogenic research apparatus. Paired with polyimide-insulated T1 (Chromel) as the positive leg, it forms a complete high-temperature-rated Type K lead pair.

Yes. Polyimide insulation remains mechanically and electrically stable from cryogenic temperatures through to its upper service limit, making it suitable for Type K thermocouple assemblies in cryogenic measurement environments. The Alumel alloy itself is non-superconducting and maintains its thermoelectric properties at low temperatures, though Type K is less commonly specified for cryogenic measurement than Type T due to Type T's superior accuracy below ambient temperatures.

The bare Alumel spooled wire is the raw alloy without insulation, suited to thermocouple elements that will be enclosed in ceramic sleeves, mineral-insulated sheaths, or other protective structures where insulation is applied separately. This insulated version is the ready-to-use lead wire format for the same alloy, where the polyimide insulation is already applied and provides the electrical isolation needed in open-lead thermocouple assemblies and extension cables. Choose bare wire for sensor element fabrication; choose insulated wire for thermocouple lead wiring.

Polyimide-Insulated T2 Thermocouple Wire (Ni95-(Al+Mn+Si)5) is available in a range of diameters and lengths. Diameter tolerance is ±10% and length tolerance is +5% / −1%. For custom configurations or non-standard requirements, please contact us.