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Insulation
Fundamentals
- Heat
always flows from warmer to colder areas.
This movement or transfer of heat occurs
by one or any combination of three following
methods:
- Conduction
- Convection
- Radiation
An
example of all three methods of heat flow
occurs in the wall space of buildings. The
following graphs demonstrate the effects
of adding reflective surface and of
filling the air space with an insulation
material such as EPS. Clearly, heat transfer
by convection, a major component of heat
flow, can be almost eliminated by the use
of insulation.
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Requirements
For Cold Storage Insulation
The
most important characteristics of a suitable insulation
material are:
- Low
Thermal Conductivity
- High
water resistance, and
- Durability
at low temperature
Other
properties like easy workability, negligible capillary
absorption should also be taken into consideration
while making a selection.
K-Value
- The
comparison of thermal conductivity can
be measured by the 'k' value. The 'k'
value, of Thermal Conductivity,
specifies the rate of heat transfer in
any homogeneous material.
- If
a material has a k value of 1, it means
a 1m cube of material will transfer heat
at a rate of 1 watt for every degree of
temperature difference between opposite
faces.
- The
lower this value is, the less heat the
material will transfer.
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The
Effect Of Moisture On Insulating Materials
- Of
all materials used for insulation applications,
EPS is one of the most resistant to the adverse
effects of moisture.
- Condensation,
which may build up within any insulation material
under critical vapor flow conditions, only marginally
affects the thermal performance of EPS.
- Even
if condensation develops through imporper use
EPS will retain its dimensional stability and
superior insulation values.
Comparison
Of Insulating Material Performance Wise
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(Ref
: IS 661-1977)
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Rice
Husk
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| Water
Vapor Transmission |
30
Times compared to EPS |
| Thermal
Conductivity compared to EPS at 22 density |
Not
Equal even at 200 D |
| Water
Absorption |
140
Times more |
EPS
Combines Effectively
- Exceptionally
low thermal conductivity. The thermal conductivity
of EPS is very low compared to Fiber Glass Wool
or Rice Husk and Saw Dust.
- No
deterioration of K-value on ageing.
- No
Shrinkage, Good adhesion to facing.
- Cost
effective, 50% load on power can be reduced
by proper design of cold storage.
Density V/S Thermal Conductivity
- Thermal
conductivity of EPS varies with density.
- One
should be very careful while choosing density
for insulation material.
- Its
low thermal conductivity commensurate with reasonably
lower densities makes EPS an attractive case
for both for cold and hot insulation.
Guidelines
On EPS Usage
- Ensure
proper density(minimum 18 kg/m3 is recommended
for best results).
- Ensure
thickness as per requirement(for roof: 6",
for wall: 4", for wall which is exposed
to sun:6")
- Ensure
proper installation of EPS.
- Ensure
vapor barrier application properly. It should
always be applied on warm side.
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