We've split our info on insulation into two separate pages: Insulation Data and Insulation Products. You are currently on the Insulation Data page. Here you will find charts on R values and temp tolerance for common insulative materials. The Insulation Products page is our running reference and commentary on where, what and why of various products we have tried and might have something to say about them.
Insulation for gasifiers needs to be concerned with both insulative performance and tolerance to high temperature. In general, as high temperature tolerance increases, insulative performance decreases. Most of the refractory ceramics that are survive high temps very well, also tend to be relatively poor insulators. Of course money and esoteric materials can find exceptions to this trend, but such is the starting point from which to get oriented. One can also consider layering insulation materials, so that temp resistance is favored against the heat source, and insulative performance is favored for surrounding layers.
Here now is a helpful summary chart from wikipedia for understanding relative insulation performance. Note that some relatively common materials and inexpensive materials are good insulators. Exotic high cost insulators are not necessarily an improvement. The chart shows numerically why we have found Perlite to be a great insulative value.
This chart rates insulators with their R value. A higher R value is better insulation. Formally, R value = material thickness / thermal conductivity. Thus R value is the inverse of thermal conductivity. There is a very complete thermal conductivity chart on the bottom of this page.
| Material |
Value per inch (Min) |
Value per inch (Max) |
Reference |
| Still Air |
|
R-5 (0.88) |
|
| Still Air with convective currents |
R-1 (0.18) (or less) |
R-5 (0.88) (Still) |
|
| Wood chips and other loose-fill wood products |
R-1 (0.18) |
|
|
| Snow |
R-1 (0.18) |
|
|
| Straw bale |
R-1.45 (0.26) |
|
[3] |
| Wood panels, such as sheathing |
R-2.5 (0.44) |
|
|
| Vermiculite loose-fill |
R-2.13 (0.38) |
R-2.4 (0.42) |
|
| Perlite loose-fill |
R-2.7 (0.48) |
|
|
| Rock and slag wool loose-fill |
R-2.5 (0.44) |
R-3.7 (0.65) |
[8] |
| Rock and slag wool batts |
R-3 (0.52) |
R-3.85 (0.68) |
|
| Fiberglass loose-fill |
R-2.5 (0.44) |
R-3.7 (0.65) |
[8] |
| Fiberglass rigid panel |
R-2.5 (0.44) |
|
|
| Fiberglass batts |
R-3.1 (0.55) |
R-4.3 (0.76) |
|
| High-density fiberglass batts |
R-3.6 (0.63) |
R-5 (0.88) |
|
| Cementitious foam |
R-2 (0.35) |
R-3.9 (0.69) |
|
| Cellulose loose-fill |
R-3 (0.52) |
R-3.8 (0.67) |
[9] |
| Cellulose wet-spray |
R-3 (0.52) |
R-3.8 (0.67) |
[9] |
| Cotton batts (Blue Jean Insulation) |
R-3.7 (0.65) |
|
[10] |
| Icynene spray |
R-3.6 (0.63) |
|
[11] |
| Icynene loose-fill (pour fill) |
R-4 (0.70) |
|
[11] |
| Urea-formaldehyde foam |
R-4 (0.70) |
R-4.6 (0.81) |
|
| Urea-formaldehyde panels |
R-5 (0.88) |
R-6 (1.06) |
|
| Polyethylene foam |
R-3 (0.52) |
|
|
| Phenolic spray foam |
R-4.8 (0.85) |
R-7 (1.23) |
|
| Phenolic rigid panel |
R-4 (0.70) |
R-5 (0.88) |
|
| Molded expanded polystyrene (EPS) low-density |
R-3.7 (0.65) |
|
|
| Molded expanded polystyrene (EPS) high-density |
R-4 (0.70) |
|
|
| Extruded expanded polystyrene (XPS) low-density |
R-3.6 (0.63) |
R-4.7 (0.82) |
|
| Extruded expanded polystyrene (XPS) high-density |
R-5 (0.88) |
R-5.4 (0.95) |
|
| Open-cell polyurethane spray foam |
R-3.6 (0.63) |
|
|
| Closed-cell polyurethane spray foam |
R-5.5 (0.97) |
R-6.5 (1.14) |
|
| Polyurethane rigid panel (Pentane expanded) initial |
R-6.8 (1.20) |
|
|
| Polyurethane rigid panel (Pentane expanded) aged 5-10 years |
R-5.5 (0.97) |
|
|
| Polyurethane rigid panel (CFC/HCFC expanded) initial |
R-7 (1.23) |
R-8 (1.41) |
|
| Polyurethane rigid panel (CFC/HCFC expanded) aged 5-10 years |
R-6.25 (1.10) |
|
|
| Polyisocyanurate spray foam |
R-4.3 (0.76) |
R-8.3 (1.46) |
|
| Foil-faced polyisocyanurate rigid panel (Pentane expanded ) initial |
R-6.8 (1.20) |
|
|
| Foil-faced polyisocyanurate rigid panel (Pentane expanded) aged 5-10 years |
R-5.5 (0.97) |
|
|
| Silica aerogel |
R-10 (1.76) |
|
|
| Vacuum insulated panel |
R-30 (5.28) |
R-50 (8.80) |
|
| Cardboard |
R-3 (0.52) |
R-4 (0.70) |
|
| Thinsulate clothing insulation |
R-5.75 (1.01) |
|
|
chart from Wikipedia: http://en.wikipedia.org/wiki/R-value_(insulation)
Detailed info on Perlite insulation over temp range
http://www.engineeringtoolbox.com/perlite-insulation-k-values-d_1173.html
Detailed info on Mineral Wool insulation over temp range
http://www.engineeringtoolbox.com/mineral-wool-insulation-k-values-d_815.html
Detailed Info on Fiberglass insulation over temp range
http://www.engineeringtoolbox.com/fiberglas-insulation-k-values-d_1172.html
Other R value charts
http://www.coloradoenergy.org/procorner/stuff/r-values.htm
http://www.progress-energy.com/custservice/flares/billtoolkit/rvalues.asp
Temperature limits of some common insulation materials are indicated in the table below:
| Insulation Material |
Low Temperature Range |
High Temperature Range |
| (oC) |
(oF) |
(oC) |
(oF) |
| Calcium Silicate |
-18 |
0 |
650 |
1200 |
| Cellular Glass |
-260 |
-450 |
480 |
900 |
| Elastomeric foam |
-55 |
-70 |
120 |
250 |
| Fiberglass |
-30 |
-20 |
540 |
1000 |
| Mineral Wool |
0 |
32 |
1000 |
1800 |
| Phenolic foam |
|
|
150 |
300 |
| Polyisocyanurate or polyiso |
-180 |
-290 |
150 |
300 |
| Polystyrene |
-50 |
-60 |
75 |
165 |
| Polyurethane |
-210 |
-350 |
120 |
250 |
from Engineering Toolbox: http://www.engineeringtoolbox.com/insulation-temperatures-d_922.html
Charts of Thermal Conductivity
Thermal conductivity, or heat transfer coefficients, of some common materials and products are indicated in the table below.
|
Thermal Conductivity - k - (W/mK)
|
|
Material/Substance
|
Temperature (oC)
|
|
25
|
125
|
225
|
|
Acetone
|
0.16
|
|
|
|
Acrylic
|
0.2
|
|
|
|
Air
|
0.024
|
|
|
|
Alcohol
|
0.17
|
|
|
|
Aluminum
|
250
|
255
|
250
|
|
Aluminum Oxide
|
30
|
|
|
|
Ammonia
|
0.022
|
|
|
|
Antimony
|
18.5
|
|
|
|
Argon
|
0.016
|
|
|
|
Asbestos-cement board
|
0.744
|
|
|
|
Asbestos-cement sheets
|
0.166
|
|
|
|
Asbestos-cement
|
2.07
|
|
|
|
Asbestos, loosely packed
|
0.15
|
|
|
|
Asbestos mill board
|
0.14
|
|
|
|
Asphalt
|
0.75
|
|
|
|
Balsa
|
0.048
|
|
|
|
Bitumen
|
0.17
|
|
|
|
Benzene
|
0.16
|
|
|
|
Beryllium
|
218
|
|
|
|
Brass
|
109
|
|
|
|
Brick dense
|
1.31
|
|
|
|
Brick work
|
0.69
|
|
|
|
Cadmium
|
92
|
|
|
|
Carbon
|
1.7
|
|
|
|
Carbon dioxide
|
0.0146
|
|
|
|
Cement, portland
|
0.29
|
|
|
|
Cement, mortar
|
1.73
|
|
|
|
Chalk
|
0.09
|
|
|
|
Chrome Nickel Steel (18% Cr, 8 % Ni)
|
16.3
|
|
|
|
Clay, dry to moist
|
0.15 - 1.8
|
|
|
|
Clay, saturated
|
0.6 - 2.5
|
|
|
|
Cobalt
|
69
|
|
|
|
Concrete, light
|
0.42
|
|
|
|
Concrete, stone
|
1.7
|
|
|
|
Constantan
|
22
|
|
|
|
Copper
|
401
|
400
|
398
|
|
Corian (ceramic filled)
|
1.06
|
|
|
|
Corkboard
|
0.043
|
|
|
|
Cork, regranulated
|
0.044
|
|
|
|
Cork
|
0.07
|
|
|
|
Cotton
|
0.03
|
|
|
|
Carbon Steel
|
54
|
51
|
47
|
|
Cotton Wool insulation
|
0.029
|
|
|
|
Diatomaceous earth (Sil-o-cel)
|
0.06
|
|
|
|
Earth, dry
|
1.5
|
|
|
|
Ether
|
0.14
|
|
|
|
Epoxy
|
0.35
|
|
|
|
Felt insulation
|
0.04
|
|
|
|
Fiberglass
|
0.04
|
|
|
|
Fiber insulating board
|
0.048
|
|
|
|
Fiber hardboard
|
0.2
|
|
|
|
Fireclay brick 500oC
|
1.4
|
|
|
|
Foam glass
|
0.045
|
|
|
|
Freon 12
|
0.073
|
|
|
|
Gasoline
|
0.15
|
|
|
|
Glass
|
1.05
|
|
|
|
Glass, Pearls, dry
|
0.18
|
|
|
|
Glass, Pearls, saturated
|
0.76
|
|
|
|
Glass, window
|
0.96
|
|
|
|
Glass, wool Insulation
|
0.04
|
|
|
|
Glycerol
|
0.28
|
|
|
|
Gold
|
310
|
312
|
310
|
|
Granite
|
1.7 - 4.0
|
|
|
|
Gypsum or plaster board
|
0.17
|
|
|
|
Hairfelt
|
0.05
|
|
|
|
Hardboard high density
|
0.15
|
|
|
|
Hardwoods (oak, maple..)
|
0.16
|
|
|
|
Helium
|
0.142
|
|
|
|
Hydrogen
|
0.168
|
|
|
|
Ice (0oC, 32oF)
|
2.18
|
|
|
|
Insulation materials
|
0.035 - 0.16
|
|
|
|
Iridium
|
147
|
|
|
|
Iron
|
80
|
68
|
60
|
|
Iron, wrought
|
59
|
|
|
|
Iron, cast
|
55
|
|
|
|
Kapok insulation
|
0.034
|
|
|
|
Kerosene
|
0.15
|
|
|
|
Lead Pb
|
35
|
|
|
|
Leather, dry
|
0.14
|
|
|
|
Limestone
|
1.26 - 1.33
|
|
|
|
Magnesia insulation (85%)
|
0.07
|
|
|
|
Magnesite
|
4.15
|
|
|
|
Magnesium
|
156
|
|
|
|
Marble
|
2.08 - 2.94
|
|
|
|
Mercury
|
8
|
|
|
|
Methane
|
0.030
|
|
|
|
Methanol
|
0.21
|
|
|
|
Mica
|
0.71
|
|
|
|
Mineral insulation materials, wool blankets ..
|
0.04
|
|
|
|
Molybdenum
|
138
|
|
|
|
Monel
|
26
|
|
|
|
Nickel
|
91
|
|
|
|
Nitrogen
|
0.024
|
|
|
|
Nylon 6
|
0.25
|
|
|
|
Oil, machine lubricating SAE 50
|
0.15
|
|
|
|
Olive oil
|
0.17
|
|
|
|
Oxygen
|
0.024
|
|
|
|
Paper
|
0.05
|
|
|
|
Paraffin Wax
|
0.25
|
|
|
|
Perlite, atmospheric pressure
|
0.031
|
|
|
|
Perlite, vacuum
|
0.00137
|
|
|
|
Plaster, gypsum
|
0.48
|
|
|
|
Plaster, metal lath
|
0.47
|
|
|
|
Plaster, wood lath
|
0.28
|
|
|
|
Plastics, foamed (insulation materials)
|
0.03
|
|
|
|
Plastics, solid
|
|
|
|
|
Platinum
|
70
|
71
|
72
|
|
Plywood
|
0.13
|
|
|
|
Polyethylene HD
|
0.42 - 0.51
|
|
|
|
Polypropylene
|
0.1 - 0.22
|
|
|
|
Polystyrene expanded
|
0.03
|
|
|
|
Porcelain
|
1.5
|
|
|
|
PTFE
|
0.25
|
|
|
|
PVC
|
0.19
|
|
|
|
Pyrex glass
|
1.005
|
|
|
|
Quartz mineral
|
3
|
|
|
|
Rock, solid
|
2 - 7
|
|
|
|
Rock, porous volcanic (Tuff)
|
0.5 - 2.5
|
|
|
|
Rock Wool insulation
|
0.045
|
|
|
|
Sand, dry
|
0.15 - 0.25
|
|
|
|
Sand, moist
|
0.25 - 2
|
|
|
|
Sand, saturated
|
2 - 4
|
|
|
|
Sandstone
|
1.7
|
|
|
|
Sawdust
|
0.08
|
|
|
|
Silica aerogel
|
0.02
|
|
|
|
Silicone oil
|
0.1
|
|
|
|
Silver
|
429
|
|
|
|
Snow (temp < 0oC)
|
0.05 - 0.25
|
|
|
|
Sodium
|
84
|
|
|
|
Softwoods (fir, pine ..)
|
0.12
|
|
|
|
Soil, with organic matter
|
0.15 - 2
|
|
|
|
Soil, saturated
|
0.6 - 4
|
|
|
|
Steel, Carbon 1%
|
43
|
|
|
|
Stainless Steel
|
16
|
17
|
19
|
|
Straw insulation
|
0.09
|
|
|
|
Styrofoam
|
0.033
|
|
|
|
Tin Sn
|
67
|
|
|
|
Zinc Zn
|
116
|
|
|
|
Urethane foam
|
0.021
|
|
|
|
Vermiculite
|
0.058
|
|
|
|
Vinyl ester
|
0.25
|
|
|
|
Water
|
0.58
|
|
|
|
Water, vapor (steam)
|
|
0.016
|
|
|
Wood across the grain, white pine
|
0.12
|
|
|
|
Wood across the grain, balsa
|
0.055
|
|
|
|
Wood across the grain, yellow pine
|
0.147
|
|
|
|
Wood, oak
|
0.17
|
|
|
|
Wool, felt
|
0.07
|
|
|
from Engineering Toolbox: http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html
Here are some more charts of Thermal Conductivity
http://en.wikipedia.org/wiki/Thermal_conductivity
http://en.wikipedia.org/wiki/List_of_thermal_conductivities
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