Friday, January 20, 2012

Thermocouple Wire Insulation Types

There are many different types of thermocouple wire insulation based on the specific application required for each use.  Generally, the larger the wire diameter, the less flexible it will be.  The smaller the diameter flexibility increases but at the cost of strength.  The most common sizes are 20 and 24 awg solid or stranded.  30 and 36 awg sizes are also used for special applications.  Stranding will increase the flexibility with a minimal increase in overall diameter.   As you may assume the better the insulation is for temperature, moisture and abrasion resistance, the higher the cost.  This list shows the most common insulations starting with the least expensive.   
 
 
Insulation         Upper Temp                        Resistance to                       Typically
Type                        Limit                        Moisture     Abrasion                 used for
 
PVC              105 C (221 F)              Excellent        Good            Extension

Ripcord         Same as PVC                                                        T/C

Glass Braid     540 C (1000 F)             Good            Fair                T/C
High Temp

Glass Braid     870 C (1600 F)             Good            Good              T/C

Teflon FEP     260 C (500 F)              Excellent        Excellent          T/C
Extruded

Teflon TFE     316 C (600 F)              Excellent        Good              T/C
Tape wrap

Kapton          427 C (800 F)              Excellent        Excellent          T/C

Wire preparation also increases in difficulty as Glass braids, Teflon TFE and Kapton are harder to strip as compared to PVC. Thermal strippers can help but Teflon FEP is known to creep when heated.

Stainless Steel wire overbraid is also added to the wire for increased abrasion resistance and to help in high vibration applications. Stainless Steel interlocking armor is also used for applications where the wire may be subjected to extreme abuse.

Part number breakdown, K24-2-305

K – Calibration
24 – Gauge size
2 – Solid wire, – 4 stranded, thermocouple grade
6 – Solid wire, – 8 stranded, extension grade

If you don't see what you are looking for here, or if you have additional questions please feel free to contact Temprel at 1-800-582-5098.

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