Insulation and Insulating materials..ppt

Insulation

1. Insulation And
Insulating Materials
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MOHD REZA KHAN
PGDIP/MAR-13/58PT/28

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3. Insulation And Insulating Materials
Insulation
What is Insulation
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 Material that retards or prevents the
progression or transmission of
 electricity
heat, moisture,
 shock, or sound from one
item or medium to another.

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Purpose of insulation:
oEnergy Saver
oTo maintain process condition
oFor personnel protection
oTo retard heat transfer

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Various types of insulation
1.Cold Insulation <10°C)
2.Ambient Insulation 10 °C-60°C
3.Hot Insulation 60°C-450°C and
above
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Fundamentals of heat transfer:
Conduction Transfer of heat energy within a body
or between two bodies in physical contact.
Convection : The transfer of heat by movement of
parts of a fluid within the fluid , because of
difference in the density , due to difference in
temperature of the parts of the fluid.
Radiation: The transfer of heat energy from a high
temperature body , through space , to another
lower temperature body .

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oFirst law of thermodynamics: Energy can
neither be created nor destroyed . It can only
change form. First law of thermodynamics can
not be proved mathematically but no process
in the nature is known to have violated the first
law.
oSecond law of thermodynamics: It is
impossible to construct a device that operates
in a cycle and converts all amount of heat into
work, while exchanging heat with a single
source.

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Heat:
‘Heat’ is defined as the form of energy that is
transferred between two systems , or a system
and its surrounding , by virtue of temperature
difference. Heat transfer to a system is positive
, and heat transfer from a system is considered
–ve.

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Thermal conductivity :
Thermal Conductivity of a substance determines
the quantity of heat passing per unit area at a
temp. drop of 1 °C per unit length.
oBasically it is ability to transfer heat
1 Kcal / hr. m. °C = 1.163 W/m °K
In SI Unit : Q is in J/sec or watt , Therefore unit
of k = [( J/sec)/m2] . m/°K or W/m°K

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Properties Of Thermal Conductivity:
oIt differs with each substance.
oIt depends on structure and other physical
properties.
oIt depends upon temperature.
.

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Metals K in W/m°K
Ag 410
Cu 385
Al 202
Ni 93
Fe 73
Carbon Steel 43
Lead 35
Cr-Ni Steel 16
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Thermal conductivity of various materials at
0°C :

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Conductivity:
For most pure metals it decreases with increasing
temperature.
For gases & insulating material, it increases with
rise in temperature.

13. Insulation And Insulating Materials
Insulating Material
Various insulating material
 pop
Cotton
Puf(foam)
Glass wool
Mineral wool
Plastic
Wood
cont…….
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14. Insulation And Insulating Materials
Rubber
Sag wool
EPS(Expandable Polystyrene )
Bricks
Silicon
Paper
Asbestos
Teflon/nylon
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15. Insulation And Insulating Materials
Non-metals K in W/m°K
Quartz 41.6
Magnesite 4.15
Marble 2.08
Sandstone 1.83
Glass ( window) 0.78
Maple/ Oak 0.17
Sawdust 0.059
Glass Wool 0.038
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Conductivity- Non metallic solids:

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Liquids
Liquids K in W/m°K
Mercury 8.21
Water 0.536
Ammonia 0.54
Freon 0.073
Gases
Gases K in W/m°K
Hydrogen 0.175
He 0.141
Air 0.024
Water Vapour 0.0206
CO2 0.0146
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Various forms of insulation material:
oLoose fill
oBlankets
oMoulded blocks
oSheets
oBricks/Blocks

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oPhysical properties of insulating material:
Depending upon application / uses following
physical properties of insulating material should be
considered:
•Density
•Compressive strength
•Flexibility
•Moldability
•Moisture absorption
•Aging
•Effect of temp.
•Flammability
•Ease of application

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Properties of some common insulating material:
EPS/PUF : Good for cold insulation, moldable, but
highly inflammable.
Mineral wool: Good for ambient temperature / high
temperature application , non inflammable.
Refractory / Ceramic : Good for very high temp.,
high compressive strength, no moisture
absorption.

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Method of application of insulating material
Cold Insulation Hot insulation
Clean Surface Clean surface
Bitumen Primer Anticorrosive / heat resistance
Vapour Barrier painting
( Like Glass cloth/ Apply glass wool / mineral wool
plastic film) Wire bands
Wooden battens Wire mesh netting
EPS slabs - Ist layerAl sheet cladding
EPS slabs - IInd layer
Bitumen seal coat
Wire netting
Sand / Cement plaster
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Design parameters for insulation system:
•Controlling heat loss from hot piping
•Providing personal protection
•Providing personal comfort in commercial
building
•Reducing heat gain by cold piping
•Reducing surface condensation
•Economic optimization of energy conservation

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25. Insulation And Insulating Materials
Selection of Insulating Material
Following are the steps in selection of insulation material /
system:
• Select design criteria
• Specify inside / outside temperature
• Specify insulation material
• Find optimum insulation thickness
• Specify application techniques
• Finalize complete insulation system
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26. Insulation And Insulating Materials
Optimum Thickness of Insulation
 Cost of insulation increases with increased of
thickness
 Cost of heat loss decreases with increase in
insulation thickness
There will be a optimum thickness where further
increase does not have sufficient heat to justify the
cost
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