What is corrosion protection?
steel corrosion protection via Desiccant method
According to DIN 55 473, the purpose of using desiccants is as follows: "desiccant bags are intended to protect the package contents from humidity during transport and storage in order to prevent corrosion, mold growth and the like
The desiccant bags contain desiccants which absorb water vapor, are insoluble in water and are chemically inert, such as silica gel, aluminum silicate, alumina, blue gel, bentonite, molecular sieves etc.. Due to the absorbency of the desiccants, humidity in the atmosphere of the package may be reduced, so eliminating the risk of corrosion. Since absorbency is finite, this method is only possible if the package contents are enclosed in a heat-sealed barrier layer which is impermeable to water vapor. This is known as a climate-controlled or sealed package. If the barrier layer is not impermeable to water vapor, further water vapor may enter from outside such that the desiccant bags are relatively quickly saturated, without the relative humidity in the package being reduced.
"A desiccant unit is the quantity of desiccant which, at equilibrium with air at 23 ± 2°C, adsorbs the following quantities of water vapor:
Calculation of required number of desiccant units
The number of desiccant units required is determined by the volume of the package, the actual and desired relative humidity within the package, the water content of any hygroscopic packaging aids, the nature of the barrier film (water vapor permeability).
Formula for calculating the number of desiccant units in a package (DIN 55 474):
n = (1/a) × (V × b + m × c + A × e × WVP × t)