(1) When the product is packaged, the initial moisture contained in the air in the package. For example, the volume of product packaging is 1 cubic meter, the initial temperature and humidity during packaging are 23℃, and when the relative humidity is 85%, the air contains 17.47 grams of water.

(2) The moisture contained in the packaging accessories in the product packaging will gradually evaporate during storage and transportation. For example, wood usually has a moisture content of 15-30%.

(3) In the process of storage and transportation, water vapor permeating into product packaging is blocked. For example, a barrier PE bag with a water vapor permeability of 2g/m2/day, with an area of 6m2, will permeate 1080g of water into the package after 90 days.

4. Calculation formula and parameters of desiccant dosage

n =1/a*( V *b+ m * c + A *e* WDD * t )

N: number of unit of desiccant required.

A: the amount of water vapor that can be absorbed by one unit of desiccant under the target humidity condition (g)

V: internal volume of package (m3)