Thermal Insulators:

Thermal Insulators:

The materials having extremely low thermal conductivity are called as thermal insulators. The heat flow rates can be considerably reduced with the use of insulating materials.

Desired properties of an ideal insulating material:

1. Low heat conductivity: Lower the heat conductivity less is the thickness of insulation required.
2. Permeance: Materials may disintegrate as a result of internal chemical activity or as a result of exposure to surrounding conditions. The insulating materials must have high resistance to compression, resiliency and vibration.
3. Strength: The insulating materials must withstand pressure coming on them, structural strength can be improved by use of wood or frame work.
4. Light weight: This becomes more important point for insulation in ship airplanes and automobiles.
5. Water repellent: Moisture absorbed by the insulating material increases conductivity and reduces strength so an insulator must be good water repellent.
6. Odourless: It should not give any odour, which can make working environment uncomfortable.
7. Low cost and easily available.