It is important to understand how the desiccant does its job of protecting the product. Most porous adsorbents, such as silica gel, activated clay or molecular sieves rely upon physical adsorption rather than chemical adsorption to accomplish their function.
In a porous desiccant such as the calcium chloride used by TOPDRY, water is removed from the airspace by:
Δ Calcium Chloride is the most aggressive absorber. As the salt absorbs moisture from the air a saline solution – a brine – is formed. This brine needs to be handled with care. It is strongly corrosive on metals. If left exposed to the air, the brine will under some circumstances give up the moisture it as absorbed in a way that can cause great damage, in some cases even leaving a briny pool.
Δ TOPDRY Desiccant extracts water vapor from the air, thus preventing the humidity inside the container reaching dew point and condensing. Once water vapor has been absorbed, the desiccant turns to gel and the water is retained by binding agents.
Δ All the TOPDRY desiccants are based on the use of high grade Calcium Chloride to aggressively remove moisture from the air. The resulting brine is collected in a bag where it is safely sequestered from further contact with the air. This simple principle is the bass of superior functional properties of composite membrane and spunbond.
Δ All TOPDRY desiccant bags with a special system of double packing:Tyvek and Spunbond. Spunbond Polypropylene is a nonwoven fabric composed of thermally bonded, continuous polypropylene filaments. The structure gives it good filtration properties and tensile strength even in diagonal direction. In addition, it is made of 100% polypropylene, which makes it resistant to moisture and chemical attack.
Δ A high absorption capacity. - TOPDRY desiccants can absorb up to 200% of its own weight for 60-90 days when its fully maximize. Exactly how much moisture the salt will absorb depend on the temperature and humidity, but it is often more than 130%.
Δ A high absorption rate. – When the temperature changes quickly, a lot of moisture needs to be absorbed in short time to prevent condensation from dripping onto the cargo. The rate depends on the temperature and humidity, but may reach 10g/hour or more.