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## Classification of Insulators The classification of insulators is based on their chemical nature and state. There are three types of insulators: - **Solid Insulators**: e.g. wood, paper - **Liquid Insulators**: e.g. Mineral oils - **Gaseous Insulators**: e.g. Carbon dioxide (CO₂), dry air, nitro...

## Classification of Insulators The classification of insulators is based on their chemical nature and state. There are three types of insulators: - **Solid Insulators**: e.g. wood, paper - **Liquid Insulators**: e.g. Mineral oils - **Gaseous Insulators**: e.g. Carbon dioxide (CO₂), dry air, nitrogen Solid, liquid, and gaseous insulators can also be classified depending on their chemical nature. ### Organic Insulators The organic thermal insulators are useful for low-temperature work, up to 150°C. ### Inorganic Insulators Inorganic insulators are suitable for temperatures higher than 150°C. Inorganic insulators are asbestos paper, asbestos fiber, glass fiber, glass wool, mineral slag fiber, calcium silicate, porous silica, refractive insulating bricks etc. The most commonly used insulators are (a) Glass wool (b) Thermocole. ## Glass Wool ### Properties of Glass Wool - The average diameter of the glass wool fiber is 0.0005 cm. - Its density is low. - It has low electrical conductivity. - Glass wool has low thermal conductivity (about 0.034 kcal/m³/°C/hr). ### Preparation of Glass Wool Glass filaments are manufactured by forcing molten mass of alkali-free glass through sieve holes having the average diameter of 0.0005 cm. The filaments of glass so obtained are continuously thrown over a rapidly revolving drum to get material in wool-like form.