insulating material

Insulating Material

Building Construction Material

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 ofenergy waves; it may not be insulator against heat or electricity orsound or more than one of the two transmissions.

• The importance of Insulating material cannot be overemphasized in engineering practice. Since heat and electricityare the main source of energy in many important operations, asafe handling of these source may be impossible withoutinsulators. The insulator may be studied under three generalheadings, thermal insulators, electrical insulators and soundinsulators.

Insulating Material

Thermal Insulator

• The main function of thermal insulator is to act as apartial or total barrier in the passage of heat. Athermal insulator, therefore, should posses followingproperties;

• 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 notbreak on repeated heating and cooling.

• It should be stable chemically and physically at hightemperature for prolonged period at stretch.

• It should be resistant to moisture and vibration andhave good strength too.

Thermal Insulator

Thermal Insulator

• The situation where a thermal insulator maybe required are varied.

• The flow of Heat has to be stopped from aworking place to the outside environment, suchas furnace to outside;

• The flow of heat has to be stopped from anoutside source to a place, for instance in specialrooms where equipment is to be worked at lowtemperature or comfort has to be insured in ahot climate from inside living.

Thermal Insulator

Types of Heat Insulators

• Following are some common heat Insulating materialsused in engineering Industries;

Magnesium Plastic

• This consist of thoroughly blended mixture ofhydrated magnesium carbonate and asbestos. It isapplied as a plastic mass cover over the surface fromwhich the escape of Heat is to be controlled.

Aluminum foils.

• These are essentially thin sheets made fromaluminum and its alloys. When wrapped over steampipes and other appliance, it serves as a goodinsulating material.

Magnesium Plastic

Aluminum Foils


Asbestos

• It is one of the best heat insulating material forbig and small applications alike. Insulatingsheets made from asbestos mixing some clay inthe presence of a suitable binder are used forinsulating boilers and also for bulk head liningin ships.

Cork

• It is light weight external tissue or bark of theoak tree. It has been found to be good heatinsulator and is used much for the same purpose.

Asbestos


Cellular Rubber

• It is special variety of rubber made extra porousduring manufacture. This rubber is used as aninsulator in cold storage.

Mineral Wool

• It is also called rock wool . This material is obtainedcommercially from impure limestone. The rock isfirst heated to melting temperature, Jet of air or wateris made to fall on streams of this molten rock whichsolidifies into wool like structure. Clay and dolomiteare also used for making mineral wool.

Cellular Rubber

Mineral Wool

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

Vermiculite

Electrical Insulators

• Following are the requisite qualities for anelectrical insulator,

• A very poor electrical conductivity i.e. a very highelectrical resistivity

• Resistance to deterioration on heating

• Very low thermal expansion

• Non-Inflammable

• Chemical Stability at high temperature,

• High Strength, hardness and resistance toabrasion.


Mica

• The name indicates a group of natural mineralshaving a sheet like structure by virtue of which theycan be separated into thin elastic sheets of this grouptwo members, named Muscovite and Phlogopite areused extensively as electrical insulators.

• These minerals have very low thermal conductivity,high electrical resistance, great toughness, flexibilityand resilience a unique combination for an idealinsulator. Mica in different forms is used in a varietyof electrical devices such as resistance to electricalheating appliances,


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.

Asbestos

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

Rubber


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.


Synthetic Resin

• These artificial materials have occupied aplace of great importance in the field ofelectrical insulation.

• They are available both in solid and liquidform among the solid product of celluloseester and phenolic vinyles etc are importantBakelite is an outstanding example of thisgroup

Synthetic Resin (Bakelite)


Porcelain

• It is a burnt mixture of Clay, feldspar andQuartz It forms an important group ofinsulating material which are characterized with :

High Stability

• Sufficient Hardness

• Imperviousness to moisture

• These properties make ceramic material moresuitable for high Voltage Insulation, switch boxes,condensers and other heating elements.

Porcelain


Glass

• It is also an insulating material having manyapplications among the main qualities of glassmay be mentioned chemical inertness, stability athigh temperature resistance to moisture.

Cotton

• In the form of cloth, cotton finds extensive useas an insulating cover, its properties are alsoimproved by impregnating it with oils andcoating varnishes.

Cotton

Sound Insulation

• High noise is fast becoming acute problem in many citiesand tow and.

• Insulation against noise is an important an engineeringproblem as against heat in fact in cosmopolitan cities“Noise Pollution” is one of the biggest challenges for thecitizens

Following material are used at present as acousticInsulator:

Cellular Concrete.

• It is a variety of concrete in which voids are createdduring manufacturing stage. Generally it is made byadding powdered aluminum and water to a cement usedfor making concrete.

Cellular Concrete

Sound Insulation

Sound Insulation

Acoustic Plaster

• This is made by mixing together magnesiumoxychloride granulated slag and some gelatin

Acoustic Boards

• These are made by bonding together fibrousmaterials like wood and vegetable fibers in amatrix of plaster, they are light in weight andcan be cut and joined on the ceiling and partitionwall.

• Acoustic boards are also made by usingVermiculates and Perlite.

Acoustic Plaster

Acoustic Boards

References

• Building Construction : Dr B.C. Punmia

• Civil Engineering Material : Prof. Singh

• Internet Web Sites

Thanks…