MATERIAL FEATURES
MAIN REQUIREMENTS FOR INSULATION MATERIALS
What physical insulations features depends on
HEAT CONDUCTION
The lower material's heat conduction the bigger resistance to heat transference (i.e. better heat insulation). Heat conduction rate - the main value for proper insulation thickness calculation. Also make difference:
1. density (kg/m3);
2. humidity absorbtion (%);
3. material structure (porosity, beam and other).
Heat insulating internal is also definable according permanent air flow and it's stability in material. Anti-condensation feature - the main requirement for cold surface insulation. So temperature on material surface should not be lower than temperature of dew drop. Proper insulation thickness can be calculated considering heat conductivity. Eventually heat conductivity can increase, if insulation absorbs humidity from air. In this way, thickness of insulation, counted considering those factors, is not enough to avoid the condensate formation
Lasting heat insulation should correspond those requirements:
-Obligatory tecnical features for material purchased by costumer.
-Tecnical characteristics of material should not change eventually.
Superficial valuation of the problem can minimize all attempts to save the energy...
PERMEABILITY ( µ)
The main characteristic of heat insulation, used for cold surface, is permeability. Concerning difference of pressure water steam flow forms from air. It's gains from warmer insulation surface (outside) to coldest surface. Difference of pressure accures through different temperature of opposite surfaces. Water is good heat conductor. Humidity saturation increases material heat conductivity. The bigger resistance to moisture permeability, the longer insulation is effective and preserve original technical characteristics. Resistance to moisture permeability - proportion of air steam conduction and material steam conduction,with the same conditions.
If thermal insulation is not waterproof, it is inexpended to use. Resistance to moisture permeability of insulation made of foam rubber definable according those parameters.
1. internal structure of closed cells;
2. small pores;
3. tight bind molecules in pores paries and cohesion of pores;
4. material solidity in point of resistance to moisture permeability.