Insulating material

Insulating material

1. Insulating Material Building Construction Material

2. Insulating Material All those material that retard or stop the flow of Heat Electricity Sound through them may be broadly defined as insulating materials . The same material may not be insulator against all the three types of energy waves; it may not be insulator against heat or electricity or sound or more than one of the two transmissions. The importance of Insulating material cannot be over emphasized in engineering practice. Since heat and electricity are the main source of energy in many important operations, a safe handling of these source may be impossible without insulators. The insulator may be studied under three general headings, thermal insulators, electrical insulators and sound insulators.

3. Insulating Material

4. Thermal Insulator The main function of thermal insulator is to act as a partial or total barrier in the passage of heat . A thermal insulator, therefore, should posses following properties; It should have very low thermal conductivity ; It should have a very high softening point . It should be stable to thermal shocks, i.e. should not break on repeated heating and cooling . It should be stable chemically and physically at high temperature for prolonged period at stretch. It should be resistant to moisture and vibration and have good strength too .

5. Thermal Insulator

6. Thermal Insulator The situation where a thermal insulator may be required are varied . The flow of Heat has to be stopped from a working place to the outside environment , such as furnace to outside; The flow of heat has to be stopped from an outside source to a place , for instance in special rooms where equipment is to be worked at low temperature or comfort has to be insured in a hot climate from inside living.

7. Thermal Insulator

8. Types of Heat Insulators Following are some common heat Insulating materials used in engineering Industries; Magnesium Plastic This consist of thoroughly blended mixture of hydrated magnesium carbonate and asbestos . It is applied as a plastic mass cover over the surface from which the escape of Heat is to be controlled. Aluminum foils . These are essentially thin sheets made from aluminum and its alloys. When wrapped over steam pipes and other appliance, it serves as a good insulating material.

9. Magnesium Plastic

10. Aluminum Foils

11. Types of Heat Insulators Asbestos It is one of the best heat insulating material for big and small applications alike . Insulating sheets made from asbestos mixing some clay in the presence of a suitable binder are used for insulating boilers and also for bulk head lining in ships. Cork It is light weight external tissue or bark of the oak tree. It has been found to be good heat insulator and is used much for the same purpose.

12. Asbestos

13. Cork

14. Types of Heat Insulators Cellular Rubber It is special variety of rubber made extra porous during manufacture. This rubber is used as an insulator in cold storage. Mineral Wool It is also called rock wool . This material is obtained commercially from impure limestone . The rock is first heated to melting temperature, Jet of air or water is made to fall on streams of this molten rock which solidifies into wool like structure. Clay and dolomite are also used for making mineral wool.

15. Cellular Rubber

16. Mineral Wool

17. Vermiculite Vermiculite These are group of mica like foliated minerals, some variety of vermiculites are processed for manufacturing of heat insulators that are specially useful for furnace insulations

18. Vermiculite

19. Electrical Insulators Following are the requisite qualities for an electrical insulator, A very poor electrical conductivity i.e. a very high electrical resistivity Resistance to deterioration on heating Very low thermal expansion Non-Inflammable Chemical Stability at high temperature, High Strength, hardness and resistance to abrasion.

20. Electrical Insulators

21. Electrical Insulators Mica The name indicates a group of natural minerals having a sheet like structure by virtue of which they can be separated into thin elastic sheets of this group two members, named Muscovite and Phlogopite are used extensively as electrical insulators . These minerals have very low thermal conductivity, high electrical resistance, great toughness, flexibility and resilience a unique combination for an ideal insulator. Mica in different forms is used in a variety of electrical devices such as resistance to electrical heating appliances,

22. Mica

23. Electrical Insulators Asbestos Highest Grade of asbestos which occurs in long fibre and is free from iron oxides is a commonly used insulator in many electrical appliances. It is used for covering electrical covering in traction type electrical motor or coil .

24. Asbestos

25. Rubber Rubber It is one of the very common used electrical Insulator it has following Special properties Very low electrical conductivity High resistance to moisture and abrasion High flexibility High Resilience

26. Rubber

27. Electrical Insulators Paper Paper is also classed among very useful insulators for common Use . Insulation paper is specially made without addition of fillers. When impregnated with oil, its properties as an insulator get further improved.

28. Paper

29. Electrical Insulators Synthetic Resin These artificial materials have occupied a place of great importance in the field of electrical insulation. They are available both in solid and liquid form among the solid product of cellulose ester and phenolic vinyles etc are important Bakelite is an outstanding example of this group

30. Synthetic Resin (Bakelite)

31. Electrical Insulators Porcelain It is a burnt mixture of Clay, feldspar and Quartz It forms an important group of insulating material which are characterized with : High Stability Sufficient Hardness Imperviousness to moisture These properties make ceramic material more suitable for high Voltage Insulation, switch boxes, condensers and other heating elements .

32. Porcelain

33. Electrical Insulators Glass It is also an insulating material having many applications among the main qualities of glass may be mentioned chemical inertness, stability at high temperature resistance to moisture. Cotton In the form of cloth, cotton finds extensive use as an insulating cover, its properties are also improved by impregnating it with oils and coating varnishes.

34. Glass

35. Cotton

36. Sound Insulation High noise is fast becoming acute problem in many cities and tow and . Insulation against noise is an important an engineering problem as against heat in fact in cosmopolitan cities “Noise Pollution” is one of the biggest challenges for the citizens Following material are used at present as acoustic Insulator: Cellular Concrete . It is a variety of concrete in which voids are created during manufacturing stage . Generally it is made by adding powdered aluminum and water to a cement used for making concrete.

37. Cellular Concrete

38. Sound Insulation

39. Sound Insulation Acoustic Plaster This is made by mixing together magnesium oxychloride granulated slag and some gelatin Acoustic Boards These are made by bonding together fibrous materials like wood and vegetable fibers in a matrix of plaster, they are light in weight and can be cut and joined on the ceiling and partition wall. Acoustic boards are also made by using Vermiculates and Perlite .

40. Acoustic Plaster

41. Acoustic Boards

42. References Building Construction : Dr B.C. Punmia Civil Engineering Material : Prof. Singh Internet Web Sites

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