Insulation Thermocouple and Thermocouple Extension Wire Selection Guide.

Type	Flexibility	Moisture Resistance	Abrasion Resistance	Continuous Temp Rating	Single Reading Temp Rating
Fiberglass Code 302, 305	Good	Fair	Good	900F (480C)	1000F (540C)
High Temp Fiberglass Code 321	Good	Fair	Fair	1300F (700C)	1600F (870C)
PVC Code 502, 505	Very Good	Excellent	Very Good	-15 to +220 F -26 to +105C
Teflon FEP (Extruded) Code 506, 507, 509	Good	Excellent	Excellent	-90 to +400 F -67 to +205 C	500 F (260C)
Teflon TFE Tape wrap Code 508	Good	Excellent	Very Good	-90 to + 500 F -67 to + 260 C	600F (315C)
Teflon PFA Extruded Code 516	Good	Excellent	Excellent	-90 to +500 F -67 to +260 C	550F (290C)
Kapton  Tape Wrap Code 511, 513	Good	Excellent	Excellent	-90 to +600 F -67 to +315 C	800F (430C)

Fiberglass insulation is impregnated with a modified resin to enhance abrasion resistance and prevent fraying. It is retained up to 400F (205C).