dehydrating salt Archives - 360ecopackaging

In the previous post we have seen what a DIN unit is and the degree of absorption per unit, therefore we must remember that a DIN unit is equivalent to an absorption of 6g of water and that to absorb these 6g of water approximately 30g of desiccant salts are necessary (depending on the type of salt and the conditions).

Having recalled the previous post, we consider a practical case for a part of dimensions 1150x750x750mm (length x width x height) to be transported in a box equipped with a thermoweldable bag of inner dimensions 1200x800x800mm.

To calculate the volume of air enclosed between the box and the part we must find the differential of volumes, therefore:

1,2 x 0,8 x 0,8 – 1,15 x 0,75 x 0,75 = 0,121 m3

Once this data has been calculated, we go to the formula:

n = 1/a · ( V · b + m · c + A · e · D · t )

And we calculate the number “n” of DIN units replacing each constant by its value, (to know the value of these parameters do not hesitate to visit our previous post).

The result would be n = 2 approximately, so about 60g of desiccant compound would be necessary for this packaging. We must bear in mind that it is always better to distribute these salts proportionally so that the atmosphere always maintains homogeneous humidity levels, so whenever possible we will use several bags distributed homogeneously.

As we have mentioned in previous posts, it is important to define the volume of air that we want to maintain with low humidity levels in order to calculate the number of DIN units that will be necessary. Once we know this information, our supplier will tell us the exact grams of salt that we will need depending on its composition.

Dehydrating or Desiccant salts, they are used more and more frequently for the packaging of cargoes, especially in maritime transports, but … are we using the right amount of desiccant salts? what is a DIN unit? do all desiccant salts absorb the same amount of moisture? In this post we will try to answer all these questions.

To calculate the amount of DIN units of salts needed to ensure a “dry” environment, we will base ourselves on the DIN 55474 standard, which empirically defined as:

n = 1/a · ( V · b + m · c + A · e · D · t )

Where “n” is the number of DIN units, “a” the amount of water vapor absorbed per unit of salt, for 20 % RH a = 3 g; 40 % RH a = 6 g; 60 % RH a = 8 g, “V” the volume inside the packaging, “b” the humidity per unit volume of interior air, “m” weight in kilograms, “c” grams of humidity per kilogram of weight, “S” packaging surface in square meters, “e” correction factor, for 20 % RH e = 0.9, for 40 % RH e = 0.7 and finally for 60 % RH e = 0.6, “D” permeability in grams per square meter and finally “t” the storage time.

To summarize, in general, one DIN unit is equivalent to an absorption of 6g of water, to absorb these 6g of water approximately 30g of desiccant salts are necessary (depending on the type of salt and the conditions).

Thus we can take this table as a reference:

As we have already mentioned in this blog, there are many types of desiccant salts depending on their chemical composition, so we must always know their absorption capacity and the amount of DIN units per unit mass.

As a conclusion we must assume to take as reference the DIN units and from this we will be able to calculate the grams of each salt that we need. Starting from these DIN units we will never make a mistake with the amount of salts needed.

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Tag Archives: dehydrating salt

Case study, Use of Desiccant Salts

To calculate the volume of air enclosed between the box and the part we must find the differential of volumes, therefore:

Desiccant salts, absorption capacity and normalization

To calculate the amount of DIN units of salts needed to ensure a “dry” environment, we will base ourselves on the DIN 55474 standard, which empirically defined as:

Thus we can take this table as a reference: