MGO Insulated Thermocouples

With Plug or Jack | Open Terminal Head | Connection Head


MgO insulated thermocouples are manufactured by encasing the thermocouple wires together with a small diameter flexible metal sheath. The thermocouple wires are also insulated from the outer metal sheath with Magnesium Oxide powder. In fact the powder is of the highest purity. This form of construction creates a very versatile thermocouple. They can also be made in a variety of small diameters from .062" to .075". They are also available with a number of metal alloy sheaths. Type K thermocouples together with an Inconell 600 sheath is very common. See the below alloy table. Furthermore, the MgO thermocouples combination of small size and compacted insulation allows them to be used in many applications. They can survive high temperatures, pressures, as well as corrosive chemicals.


MgO insulated thermocouples are quite malleable. You can easily bend the thermocouple. In fact, you can bend it around a mandrel twice the size of its diameter. This allows installation of the thermocouple into tight spaces like around obstacles on machinery. They can also made to any length. From as small as 1 inch to many feet long. MgO thermocouples have many advantages. See below.


MGO Insulated Thermocouple Configurations

Part Numbering System Examples

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

Example: 18K4DS9-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: 8K4S9-G-K1-12 = Type K Thermocouple
Example: 8J4S9-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: 8K4S9-G-K1-12 = Type K Thermocouple with Inconel 600 Alloy sheath
Example: 8K4S16-G-K1-12 = Type K Thermocouple with 316ss Alloy sheath

Note: Other configurations are also available.

p42 MgO Swaged Pub 20171002-1
p43 MgO Swaged Pub 20171002-2
p42 MgO Swaged Pub 20181119-3
p42 MgO Swaged Pub 20171004a-4
p44 MgO Swaged Pub 20171004-5
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