income With the average temperature (surface temperature t s and medium temperature t f on average) change. Any kind of insulation material should have thermal conductivity equation. However
insulation materials in the use of the Federation of thermal conductivity higher than the initial thermal conductivity.
Especially for low-temperature pipe insulation, pipe insulation outside the wall on both sides of the persistence of temperature and humidity difference (for example, the outer environment temperature 30 ℃, relative humidity of 80 percent, the inside of chilled water 7 ℃, the maximum relative humidity of 100% ), in water vapor at the continued under pressure, water vapor will inevitably infiltrated the internal insulation materials, thermal conductivity due to water (0.56W/mK) 10 several times in the initial thermal conductivity material, so the material used in the thermal conductivity coefficient will be gradually increased, resulting in the original selected by the initial thermal conductivity of the insulation layer thickness becomes insufficient to prevent condensation.
Such as opening the structure of rock wool, glass wool can be installed by early appears, after a period of time due to damp heat of condensation leakage structural failure. The reason is that the blame for its internal water vapor infiltration of materials caused by the quantitative change.
Visible insulation materials critical to the ability of anti-water vapor permeability is directly related to the life of insulation materials.
Armstrong
rubber foam insulation materials used t years after the thermal conductivity into t and wet resistance factor u, the use of t the relationship between the number of years as follows: income t = income + (0.0377 * v * V t ) which Dampness relevant factor u and v, using the number of years t and V t related to the initial thermal conductivity .
For example, when the ambient temperature 30 ℃, relative humidity of 80 percent, ￠ 219 of chilled water (7 ℃) effective Armstrong 25mm thick foam rubber insulation materials (surface coefficient 9W/m2k) insulation at:
Dampness
factor u ≥ 4,500
|
use of t years after the |
use of t years after the thermal conductivity (W / m 2 k) |
required thickness of anti-Gel |
|
0
2
4
6
8
10 |
0.0358
0.0367
0.0375
0.0383
0.0391
0.0400 |
21.5
22.0
22.5
23.0
23.5
24.0 |
Dampness
factor u ≥ 3,500
|
use of t years after the |
use of t years after the thermal conductivity (W / m 2 k) |
required thickness of anti-Gel |
|
0
2
4
6
8
10 |
0.0358
0.0369
0.0380
0.0390
0.0400
0.0411 |
21.5
22.5
23.0
23.5
24.0
24.5 |
With the use of time into the material continue to accumulate within the vapor, so that the thermal conductivity into t year-on-year increase in the thickness of the required anti-Gel § has been a corresponding increase. And obstructing the wet factor u value the higher the coefficient of income such as t increased more slowly, longer life.
On the other hand, the initial selection of the insulation layer thickness used to a certain number of years when it becomes insufficient to prevent Gel lapsed, so the initial choice of insulation should be taken into account life, and resistance value than the wet factor u high material, the initial choice of thin insulating layer thickness that is, to achieve the same life.
For life assurance in the use of anti-Gel, wet resistance factor u low value materials such as glass wool, rock wool enough to rely on the initial thickness (for example, 50,60 mm) thermal conductivity of compensation arising from the rapid increase in thickness.
