Thermocouples Miniature

With Plug or Jack | Open Terminal Head | Connection Head


Miniature Thermocouple Assemblies have a maximum service temperature of 1300°F (700°C) depending on the type and gauge of thermocouple wire used.   They have limited use at high temperatures due to the types of insulation used in their construction.   Miniature thermocouples are more flexible than MgO (swaged) types. 1/8”, 3/16” and 1/4” O.D. tube assemblies are made with silicon impregnated fiberglass insulated elements.   Standard assemblies are supplied with a floating junction and solid round pin male plug and female jack. Since the junction is floating, the tube or element can easily be replaced.   Grounded junctions can, however, if required, are available. Insert “-U” after the “4M” in the part number.


Optional 1/8” NPT stainless steel compression fitting can be attached by adding a “CF to the end of the part number.  An 1/8” NPT fitting is standard on 1/8” and 3/16” O.D. tubes.   A 1/4” NPT compression fitting is standard on all 1/4” O.D. tubes.


Miniature Thermocouple Configurations

Part Numbering System Examples

Floating Junctions (F) are standard. For Grounded junctions (G), Ungrounded (U) or Exposed Junctions (E) add "G" to "U" or "E" in the part number. Dual elements insert "D" after "4" in part number.

Example: 20K4DM9-U-K1-12

To change the standard type K thermocouple calibration. Substitute the K in the part number with the desired Type B, E, J, K, N, R, S, T, or C calibration.

Example: 20K4M9-G-K1-12 = Type K Thermocouple
Example: 20J4M9-G-J1-12 = Type J Thermocouple

Sheath Materials or Alloy Code

To change the standard Inconel 600 sheath alloy (Richards #9 Alloy Code). Substitute the 9 in the part number with the desired sheath alloy. See the table below.

Example: 20K4M9-G-K1-12 = Type K Thermocouple with Inconel 600 Alloy sheath
Example: 20K4M16-G-K1-12 = Type K Thermocouple with 316ss Alloy sheath

Note: Other configurations are also available.

p34 Miniature Pub 20171004-1
p34 Miniature Pub 20171006-2
p34 Miniature Pub 20171006-3
p36 Miniature Pub 20171006-4
p36 Miniature Pub 20171007-5
Mgo Insulated Thermocouples


  • Small diameters from .062" to .075"
  • Many high temperature alloys available
  • Flexible and easy to bend by hand down to two times the diameter of the sheath
  • Short and long lengths
  • Installation flexibility
  • Terminated with plugs, jacks, connection heads or bare leads
  • Very fast response times.
  • Uniquely economical construction
  • All calibrations; Type B, E, J, K, N, R, S, T, C, and P
  • Grounded, ungrounded, in addition to exposed junctions