FAQ & Things to know about Desiccants and their Application
Desiccant is the generic term for a group of products that are used to absorb and permanently bind moisture. Desiccants are essential in many industries and product areas, with different types of desiccants being specially applied depending on the particular use case.
As a strong partner for desiccants, TROPACK offers high-level expertise and cross-industry consulting competence in the overall context of desiccants for packaging, industrial applications, and transportation. With an extensive product range and large storage capacity we can respond flexibly and quickly to your needs. Of course, in addition to standard desiccant products, we also offer customized solutions according to your specifications.
Here we have compiled useful information and answers to frequently asked questions.
Please do not hesitate to contact us if your question is not listed.
DESICCANT WIKI
Desiccants are substances that absorb moisture or water. This can be done via two fundamentally different processes:
- The moisture is adsorbed physically; this process is called adsorption
- The moisture is chemically bound; this process is called absorption
The most commonly used desiccants are those that physically adsorb moisture:
- Clay / Bentonite
- Silica Gel
- Molecular Sieve
A desiccant product from the TROPACK-portfolio, which chemically absorbs moisture, is the container desiccant TROPAsorb.
Clay or bentonite is a natural mineral. The component montmorillonite is key for the adsorption of moisture. The greater the concentration of the montmorillonite, the higher is the adsorption capacity.
In the field of standard packaging clay is used as a primary packaging material for corrosion protection in the form of a desiccant bag according to DIN 55473 inside packagings, e.g. on long transport routes or for long-term storage.
Silica gel is an amorphous silicon dioxide, which in comparison to clay, can adsorb a higher amount of moisture. Due to its high adsorption capacity in relation to its own weight, silica gel is used particularly in compact products as a desiccant in the pharmaceutical and diagnostics sectors and in the food industry.
Silica gel adsorbs very little water vapor at low relative humidity of approx. 10%RH. Silica gel can also be used as an indicating silica gel.
For this product the white silica gel is impregnated with a color indicator, so that the saturation of the desiccant can be visually controlled by the change in color of the silica gel. Orange gel is the most frequently used indicator gel with a color change from orange (active) to white (saturated).
Molecular sieve is a synthetically produced zeolite, which is part of the group of the crystalline aluminosilicates. Molecular sieves are distinguished by their pore diameter (measured in Ångström) and can specifically adsorb other molecules, such as gases, in addition to moisture. The most frequently used type is the molecular sieve with a pore diameter of 4 Ångström.
Molecular sieves are often used in the field of pharmacy, diagnostics and electronics. Molecular sieve is particularly efficient at low relative humidity of <10% RH and low temperatures even below 10°C, where other desiccants, such as clay and silica gel, are no longer effective.
In the area of chemically active desiccants, calcium chloride is predominantly used as a desiccant for sea containers (often mixed with starch or clay). Calcium chloride has a significantly higher absorption capacity than the physically active desiccants. It can absorb up to 280% of its own weight in moisture at very high relative humidity.
However, calcium chloride as a chemically acting desiccant should only be used as a secondary packaging material outside wooden boxes, cartons or similar, as it may damage the products to be protected if it comes into direct contact with them.
In addition to the DIN 55473, which standardizes the production and packaging of desiccant bags, the DIN 55474 is a quality standard for calculating the desiccant requirements.
The calculation method defined in DIN 55474 is primarily used to reliably calculate the amount of desiccant required for a packaging. Examples of such a packaging are export packaging for sea transportation or long-term storage of certain products. The calculation is carried out along important parameters, such as dimensions of the packaging, transport time and the quality of the outer packaging in terms of water vapor permeability.
→ Use our online-calculator to calculate the correct quantity of desiccant
Based on the calculation logic of DIN 55474, recommendations can also be derived for desiccant requirements outside the area of pure packaging. In this way, important parameters from the DIN 55474 formula can be transferred to components and closed systems to determine initial starting points for test phases and qualifications.
The duration of effectiveness of the desiccant depends on different factors, e.g. on
- the amount of desiccant used
- the relative humidity inside the packaging or the component – as a rough rule, the higher the relative humidity, the faster the saturation.
- the position of the desiccant in the packaging or component: is the air circulation towards the desiccant product slowed down by baffles or other components or does the moisture move „freely“ towards the desiccant.
There are several ways to visually monitor the effectiveness of desiccant products:
- Self-adhesive humidity indicators
Self-adhesive humidity indicators can be applied to desiccant bags, which visually indicate the change in relative humidity in the interior climate (discoloration of the indicator e.g. from pink to blue) - Liquid humidity indicators
Likewise, a liquid humidity indicator solution can be applied to the desiccant bag as dots that change color as the relative humidity changes. Here, however, the display accuracy is limited. - Color indicators
Silica gels that are impregnated with color indicators (e.g. orange gel, Rubingel or Envirogel) gradually change color as the silica gel adsorbs humidity and becomes saturated- Silica gel with color indicator (indicator gel) can be used in desiccant bags, in desiccant capsules or as bulk material
- Integrated humidity indicators
Desiccant cartridges are equipped with a humidity indicator that can be read from the outside and changes color as soon as the relative humidity inside enclosures or components exceeds a limit value.
The desiccant products manufactured by TROPACK meet the requirements of both the European Union and the US FDA for food contact. From the wrapping material to the desiccant to the printing ink, the US and EU food contact specifications are met.
The corresponding declarations of conformity and harmlessness are available on request .
The physically acting desiccants can be regenerated by heating. The temperature for activation depends on the type of desiccant:
- Clay / Bentonite: approx. 150°C
- Silica Gel white: approx. 150°C
- Molecular Sieve: approx. 400-550°C
- Silica Gels with color indicator are only regenerable to a limited extent
Regenerating desiccants in bulk (loose desiccants) is often uneconomical in practice as the energy costs often exceed the product value.
Desiccants that are filled in desiccant bags, capsules or cartridges are very difficult to regenerate. Heating can damage the bags, capsules or cartridges, rendering the product unusable.
Physically acting desiccants release moisture at high temperatures:
- Clay / Bentonite: between 90 and 150°C, full regeneration starting from 150°C
- Silica Gel white: between 90 and 150°C, full regeneration starting from 150°C
- Molecular Sieve: starting at approx. 200°C, full regeneration starting from 400°C
- Silica Gel including color indicator is only regenrable to a limited extent
Desiccant products in a transparent PE-Bag – standard protective packaging – have a shelf life of approx. 6-9 months. Under good storage conditions (low humidity and room temperature) desiccants can also have a significantly longer shelf life.
Optionally, the standard packaging made of transparent PE-foil can also be packed in metal buckets as secondary packaging instead of cartons. Here, the shelf life of the original closed basic packaging can be up to 24 months. In order to be able to visually control the activity of the desiccants in stock, there is a humidity indicator in the protective packaging.
In addition to the conventional protective packaging made of PE, it is also possible to pack the desiccant bags and other desiccant products in aluminum-composite packaging, either individually or in multipacks. Here the shelf life can be extended up to 24 months depending on the packaging size.
TROPACK – you can count on us
TROPACK products comply with the highest quality standards according to DIN 55473 (12/2015). Our desiccants meet the relevant requirements established by the European Union (e.g. EC 1935/2004) and the US Food & Drug Administration FDA (e.g. 21 CFR part 175/part 177).
TROPACK quality standards are regularly verified in the form of DIN 55473 and ISO 9001 certifications.That’s something industry, the retail market and consumers alike can count on. TROPACK desiccants are food-safe, contaminant-free, odourless and renewable. (We expressly refrain from using dimethyl fumarate (DMF)!)
We’ll be glad to answer any questions you may have!
