What is desiccant and what does it do?
The three most common types of desiccants are clay, silica gel, and molecular sieve.
What are clay desiccants?
Absorcare Clay Desiccant will protect the contents of a properly sealed container during shipping and storage (i.e., the contents of a sealed container will be in the same condition as when they were packaged for shipment or storage).
Clay is the least expensive of all desiccants and highly effective within normal temperature and relative humidity ranges. It is used in most industrial applications requiring humidity control. Clay desiccant can adsorb up to 28% of its weight in water vapor at 77°F (25°C) and 80% relative humidity. At full moisture vapor capacity, Desi Pak remains dry and free-flowing. There is no apparent change in size, shape, or texture of the desiccant.
Clay desiccant works satisfactorily below 120°F (49°C). Above 120°F (49°C), there is a possibility that the clay will give up moisture rather than pull it in (silica gel or molecular sieve are suitable for such temperatures). Accordingly, anticipated storage and transportation conditions should be considered when deciding whether or not to use clay.
What is silica gel?
Much like a sponge, silica gel's interconnected pores form a vast surface area that will attract and hold water by adsorption and capillary condensation, allowing silica gel to adsorb about 40% of its weight in water vapor at 100% humidity.
As a desiccant, silica gel has an average pore size of 24 angstroms (24A). Silica gel desiccant will pull in moisture at temperatures up to 220°F (104°C). As temperatures increase above 100°F (38°C) the rate of moisture pick-up will slow down, but the silica gel will still work. Silica gel performs best at room temperatures between 70°F to 90°F (21°C to 32°C) and at high humidity between 60% to 90% relative humidity.
Absorcare Silica Gel Desiccant is designed to control moisture levels within a properly sealed container during shipment and storage. At 77°F (25°C) and 80% relative humidity, Sorb-It can adsorb approximately 35% of its weight in water vapor. However, unlike a sponge, Sorb-It remains dry and free-flowing at maximum adsorption capacity.
Desiccant City also offers several types of bulk silica gel.
What is indicating silica gel?
Desiccant City also carries orange indicating silica gel. This type is a bright orange color when dry and turns green as it becomes saturated with moisture.
The most common form sold by Desiccant City is bulk silica gel, primarily used in air drying applications.
Another use of indicating silica gel is with a moisture sensitive product that will be inspected regularly, as the indicating silica gel gives a quick visual indication of how well the product is doing. Due to the presence of cobalt chloride, indicating silica gel desiccant should never be used in contact with products for consumption, such as food or pharmaceuticals.
Indicating silica gel desiccant is also available in special packet sizes for use in electronics, pharmaceutical, or food packaging.
What is molecular sieve?
Molecular sieve is the desiccant of choice for the most demanding and unique applications. The pore structure of molecular sieve desiccant provides a higher capacity for water adsorption than either silica gel or clay at very low humidity levels. Molecular sieve also retains a higher percentage of moisture capacity at elevated temperatures; in fact, molecular sieve can hold moisture at temperatures well past 450°F (232°C). Because of its high affinity for moisture, molecular sieve is able to bring the relative humidity in packages down as low as 10% relative humidity.
The most commonly used pore size for drying applications is 4 angstroms (4A). Molecular sieve desiccant is also available in 3 angstroms (3A), 5 angstroms (5A) and 10 angstroms (13X) sizes for specific molecule separation, including gases.
Molecular sieve is the most aggressive of the primary desiccants (in terms of adsorption rate), so additional handling procedures may need to be considered.
Absorcare Molecular Sieve is for controlling moisture levels in sealed containers during shipment and storage. Desiccant City also offers several types of bulk molecular sieve.
What is a desiccant "unit"?
When do I need to include a humidity indicator card in my package?
if your package is not properly sealed
How does desiccant most effectively protect my product or package?
What industries and products use desiccant?
How much desiccant do I need?
To determine the number of "units" required to protect medium to large products/packages/areas, refer to the Desiccant Requirements Chart Unit Sizes.
To determine the number of "grams" required to protect small products/packages/areas, refer to the Desiccant Requirements Chart Gram Sizes.
You may also use our Desiccant Calculator to determine the amount of desiccant for your application.
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