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Sheathing thermocouples

Sheathing thermocouples are robust and flexible and are freely bendable along their entire length. This means that the thermocouple can be integrated perfectly into its installation location. As a result, they can be used anywhere - whether in industry, development or in laboratory environments. The sheathing thermocouple can be effectively secured using a compression-type fitting and positioned directly on the measuring point. Sheathing thermocouples can also be used in extremely high temperatures, aggressive media, in vacuums or under pressure where conventional insulation materials would fail. The thermowire pair in this case is protected by a metal sheath and the wires are insulated against the sheath and each other using a mineral powder.

At one end of the thermowire (hot end), the wires are connected to a measuring point. The sheathing is then circular welded as standard and insulated against the measuring point so that no distortion of the measuring evaluation can occur as a result of offset overlay.

At the other end of the sheathing thermocouple, part of the sheathing is removed to expose the wires and establish a connection with the connecting wire that runs to the measuring device (cold end). The sheathing thermocouple is also sealed with a heat-resistant resin at this end. This sealing is required since the magnesium oxide (MgO) used for insulation is highly hygroscopic (water-attracting) and any penetrating moisture will lower the degree of insulation. Poor insulation distorts the measurement.

We are highly flexible in terms of the design of sheathing thermocouples and we can adapt them perfectly to our customers' wishes. We offer sheathing thermocouples from a diameter of 0.25 mm and with any length. The sheathing is circular-welded as standard and insulated against the measuring point. On request, the sheathing can also be flat-welded or galvanically bonded to the measuring point.

It is also possible to choose different sheathing materials. Inconel600 is the sheathing material we use most often. In air, it has an oxidation resistance of up to +1,150 °C. It can also be used in a number of other media, including liquid sodium. Another sheathing material is stainless steel of type 1.4541. It can be used in a wide range of aggressive media. It is oxidation resistant up to 900 °C in air, and up to 650 °C in carbon dioxide. Nimonic75 is a nickel-chrome alloy. This alloy is especially suitable for use at high temperatures in aggressive media, since it is resistant to oxidation up to +1,100 °C even here. To measure even higher temperatures, platinum must be used as the sheathing material. This is generally only required in combination with thermocouple types R, S and B. In highly critical applications, the sheathing thermocouple can be installed in ceramic protective tubing.

It is also possible to choose different sheathing materials. Inconel600 is the sheathing material we use most often. In air, it has an oxidation resistance of up to +1,150 °C. It can also be used in a number of other media, including liquid sodium. A further sheathing material is 1.4541. It can be used in a wide range of aggressive media. It is oxidation resistant up to 900 °C in air, and up to 650 °C in carbon dioxide. Nimonic75 is a nickel-chrome alloy. This alloy is especially suitable for use at high temperatures in aggressive media, since it is resistant to oxidation up to +1,100 °C even here.

We also offer a wide range of connection configuration options. The sheathing thermocouple can be combined with various connecting wires. These can be supplemented with a broad array of connectors and sockets or equipped with exposed wire ends. It is even possible to install a connector or socket directly onto the sheathing thermocouple.

If you are unsure which sheathing thermocouple is best for your measuring application, or if you have very special expectations, then please get in touch with us. We would be more than happy to help you choose or develop the best measuring tool for your needs.

Typical area of application

  • Liquids
  • Gases
  • Machinery
  • Motors
  • Development

Pros

  • Corrosion-protected thermal wires
  • Can be used in aggressive media
  • High temperature range
  • Gas-tight

Cons

  • No details given

Images of sheathing thermocouples