Fire Survival Wiring

Benefits of MI Cable

Benefits of MI Cable

What is mineral insulated cable?

Mineral insulated cable (MI) is a specialist type of cable that is designed to be used in high temperatures and severe environmental conditions because it’s not flammable, so it won’t be damaged by heat.

MI cable is generally made up of copper conductor wires inside a sheath that can be made of copper, stainless steel, or Inconel, (other materials are available on request). It is insulated by packed minerals specifically magnesium oxide (MgO). Magnesium oxide is the perfect electrical insulation material because it is resistant to oxidation, ionizing radiation, and it’s stable at high temperatures both, physically and chemically.

When the MI cable has been packed with MgO, the mineral insulated cable is annealed and drawdown in size to reach the required diameter. The outer sheath works to protect the conductors, for example thermocouple wires inside from heat, chemicals, or other damage from the environment. For fire proof wiring cables the copper sheath can be covered with an extra, coloured low smoke and fume (LSF) sheath to add in both identification and an additional layer of protection from corrosion.

An MI cable can have a number of wires depending on the application, the configurations that are used most often in temperature measurement are 1, 2, or 3 pairs of conductors. Specifically designed mineral insulated cables might include extra thermocouples in customised configurations. MI cable can come in a range of diameters and lengths, depending on the unique requirements for their use. All TRM MI cables are extensively tested before shipping on to our clients.

What is MI cable used for?

Mineral insulated fire survival cables where created with critical and essential circuit protection in mind. They are ideal for use in protecting buildings and structures for example, high-rises, tunnels, airports, healthcare facilities, and industrial or petrochemical plants.

Additionally, temperature sensors made from MI cable like RTDs and thermocouples, are commonly used in corrosive and high temperature environments such as heat treatment, solid waste incinerators, sintering powdered metals, firing ceramic metals, fuel fired heat exchangers, and nuclear or hydrocarbon-based energy plants.

What are the benefits of MI cable?

Corrosion and oxidisation resistant

The metal sheath that covers MI cable works to protect the conductor wires from oxidising when used in chemically active or damp environments. A high level of corrosion resistance means mineral insulated cable is great for use in areas where failure and replacement could be extremely dangerous or even impossible to do.

For instance, MI cable is used in nuclear plants to monitor core temperatures. It would be incredibly dangerous if the temperature controllers were not getting accurate readings, and it would be challenging to attempt to repair or replace the cables in this type of environment.

Non-reactive insulation

The MgO within MI cables offers unparalleled non-reactive insulation, which prevents the conductor wires from coming into contact with either each other or caustic substances like oils, solvents, or water. This is to make sure for example that the thermocouple probes always stay accurate, which is vital in applications like heat treating or sintering where the quality of the product could be negatively affected by fluctuations in temperature.

The insulation doesn’t burn

The insulation inside MI cables does not burn, meaning it is ideal for fire protection applications where it could be disastrous if a fire broke out. MI cables are ideal for critical applications such as medical devices, power plants, and oil rigs. Simply put any essential circuits would be safer with the installation of mineral insulated cables.

High levels of precise accuracy

Since the metal sheath and MgO insulation also protects thermocouple and RTD probes, they’re not easily subject to malfunction or inaccurate temperature measurements. MI cables are carefully calibrated to achieve international standards, meaning they provide accurate and precise temperature measurements across long duty cycles with very little to no loss of accuracy at all.

Also, thanks to the mineral insulation, MI cables can effectively function in high temperature conditions without their accuracy levels being affected. This makes them very useful for kilns, firing ceramics or heat-treating metals, or any other high temperature process.

These cables retain their accuracy during and after exposure to high temperatures, making them ideal as a temperature probe in these kinds of operations. Additionally, for industries like medical devices or aerospace where safety standards are enforced strictly and deviations from processes could lead to serious or even life-threatening quality issues.

Contact TRM today for find out how we can help you with our fireproof wiring, temperature measurement, and trace heating expertise. We can create tailored solutions for business in many industries to ensure the safety of their processes.

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