MINERAL INSULATED THERMOCOUPLE

Mineral insulated construction results in thermocouples wires that are surrounded by a compacted mineral insulation (MgO) and contained ina sheath such as stainless steel or heat resisting steel. On the basis of this mineral insulated construction, a wide variety of otherwise difficult applications are possible. Compared with general-purpose (protection tube type) thermocouples, sheated thermocouples have many advantages.

Basic thermocouple theory

A thermocouple is a closed loop circuit that consists of two dissimilar metal wires welded together at both ends. When a temperatune difference exists between the two junctions, thermal electromotive force (EMF) is generated and an electric current flows in the closed circuit. The direction and magnitude of the EMF generated depend upon the tempemture of the two junctions and upon the materials making up the thermocouple, and are not affected by the size or length of the thermocouple wire. Temperatune can be measured by knowing beforehand the change of EMF per degree change of temperature for a certain thermocouple.

Features

Mineral insulated thermocouples have the following advantages over conventional protection tube or wire-insulator styles.

1.       A wide appIlcation In measurement

Small diameter thermocouple is very usefull for the place where space is at premium. Mineral insulated construction is resistant to high pressure and also used at wide range of temperature from-200°C to +1260°C.

2.  Quick response

Mineral insulated thermocouples have small heat capacity due to the small sheath size, the small thermal mass is highly sensitive to change in temperature and gives a very fast response.

3.       Easily bent for installation

The ability to form mineral insulated thermocouples on a radius twice the sheath diameter makes for simple and on-the-spot installation into complex configurations.

4.  Long Iife span

Contrary to conventional thermocouples which suffer from deterioration of electromotive force or wire disconnection, etc., mineral insulated thermocouples wires are insulated with chemically stable magnesium oxide, thus assuring a longer service life.

5. Excellent mechanical strength and pressure Resistance

The composite construction is resistant to extreamely high vibration levels, and by choosing appropriate sheath material, it is reliable to use in corrosive atmospheres and abnormally high or low temperatures. Though it has small diameter, it can withstand about 350 MPa at a temperature of 650°C.

6. Custom sheath outer diameter available

Sheath outer diameter sizes between 0.25mm and 12.7mm can be provided.

7. Custom long length

Length are available up to a maximum of 400m. Maximum length is dependent upon the sheath outer diameter.

8. Compatible with special needs

We have our own factory for making many kinds of metallic sheathed cables, therefore, we can correspond to various needs from customers.