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Dimensioning according to DIN 55 474

The following formula is used to calculate the exact amount of necessary desiccant.
DIN desiccants are always measured in desiccant units (DU) and not by weight in kilograms.

n =   1    x [( V x b ) + ( m x c ) + ( A x e x WWD x t )]
 a 
                   
  Proportion of air Merchandise + Proportion of pallets Proportion of foil
  Factor Meaning Calculated value
  n Number of desiccants (DU)
a Amount of water absorbable per desiccant unit according to the maximum humidity desired in the package Final moisture desired 20 % 40 % 50 % 60 %
Factor a 3 6 7 8
Proportion of air V Interior volume of the package in m³  
b Moisture content of the air enclosed in g/m³ Example: at 20° C and 80 % rel. humidity b = 13,83 g/m²
(siehe Climate Chart)
Merchandise + proportion of pallets m Weight of the amount of hygroscopic packaging materials in kg  
c Factor for the moisture content of the hygroscopic packaging materials in g/kg
  • 80 for wood, air-dry = 18 % Wassergehalt
  • 80 for cardboard
  • 80 for organically-based upholstered furniture
proportion of foil A Surface area of the barrier-layer envelope in m²  
e Correction factor based on the final moisture desired Final moisture desired 20 % 40 % 50 % 60 %
Factor e 0,9 0,7 0,65 0,6
WDD Water-vapour permeability of the barrier-layer envelope for the climate expected, measured in (g/m² x d) according to DIN 53 122-1 or DIN 53 112-2 Example values of suitable foils
Type of foil Testing climate 20/85 Testing climate 38/90
LD-PE 0,2 mm thick 0,4 2,0
Al composite < 0,1 0,1
A value of at least 0.1 should be put in the formula
t Total period of transport and storage in days [d]  

 

Calculation example

 

    Influencing factor Value Calculation/value
Proportion of air V Volume [m³] 40 V x b
= 553,2 g
b Moisture content in the air [g/m³] 13,83
Merchandise + Proportion of pallets m Hygroscopic material enclosed [kg] 20 m x c
= 1.600 g
c Moisture content factor air-dry
80
Proportion of foil A Surface area of envelope [m²] 65 A x e x WDD x t
= 6.552 g
e Correction factor 0,7
WDD Water-vapour permeability [ g/(m² x d) ] 0,4
t Transport + Storage Period, Days [d] 360
    Sum of the water   Sum H2O
= 8.705,2 g
  a Final moisture factor desired 6 6
  n Number of desiccant units   Sum g H2O / a
= 1.450,87 DU

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