Desiccant packs are commonly used in the parcels that are used in import and export industry during cargo or shipping to control moisture – and protect goods from damage. These packs, which can contain materials such as clay, silica gel, or calcium chloride, help maintain a dry environment inside the packaging, preventing issues like mildew, mold, rust, fungus, discoloration, deterioration of fabric quality, and corrosion, and can absorb over 300% of its weight. The perishable products are highly susceptible to such detrimental conditions due to varying levels of moisture and humidity, which are common in cargo and shipping containers, during long transits or weather changes. Since different products have varying moisture sensitivity, you need to keep in mind and choose the appropriate desiccant type and quantity based on the specific products being shipped. The amount of desiccant needed for your cargo holding products for import and export depends on the container size and the transit duration.
Excess or changing humidity levels can lead to container rain inside the shipping container during longer durations of import and export across borders. Thus, container desiccant strips can help maintain optimum levels and conditions to keep the contents dry and stable, and are suitable for ocean, truck, rail, and air shipping containers.
A desiccant pack provides sustainable, affordable, and the most efficient resolutions for moisture related damages to the import and export for supply chain industry by safeguarding the products from the ill effects of humidity during long transits and varying weather conditions. In humid conditions, metal parts are prone to rusting and corrosion due to the presence of excess moisture levels.
The use of the desiccants can efficiently remove moisture from these metal parts, packaging, and storage. The use of desiccants can help to control moisture levels inside packaging, by effectively absorbing high levels of moisture and humidity inside the cargo and shipping container, and preventing issues like mold, mildew, rust, corrosion, and microorganisms that can damage products during storage and shipment for longer durations.
The role of desiccants in moisture control
Shipping container desiccants are moisture-absorbing agents designed to combat the moisture-related challenges plaguing shipping containers during transit. Their role is to maintain a dry and stable environment. By adsorbing excess moisture, desiccants play a pivotal role in preventing condensation, inhibiting mold and mildew growth, and the corrosive effects of humidity. Essentially, they act as sentinels of cargo quality, ensuring that moisture-related issues do not compromise the goods.
Shipping container desiccants can also absorb moisture up to 280% of their dry weight, unlike other desiccants such as silica gel and activated clay, which only have an absorption rate of 25-30%. Moreover, its leak-proof packaging materials allow water vapour to be absorbed and transformed into a thick gel-like structure, eliminating the potential for liquid spillage.
Condensation occurs when warm, moist air meets cooler surfaces within the container, leading to the formation of water droplets. Shipping container desiccants actively absorb excess moisture from the air, reducing the risk of condensation on the cargo or container walls. This prevention of condensation helps safeguard cargo from moisture-related damage, such as rust, mold, or packaging deterioration. High humidity levels within shipping containers can pose a significant threat to cargo. Desiccants maintain the Relative Humidity (RH) at safe levels by continuously absorbing moisture. By doing so, they create a dry environment that safeguards goods from the harmful effects of humidity, including spoilage, degradation, and the proliferation of microorganisms.
Many types of cargo, including electronics, pharmaceuticals, and food products, require strict environmental controls to maintain their quality and safety standards. Shipping container desiccants aid in preserving the product quality by ensuring that the cargo remains in optimal condition throughout the transit. By controlling moisture-related issues, desiccants help prevent costly product spoilage or rejection due to compromised quality.
International regulations and quality standards often require cargo to be transported under specific environmental conditions. Shipping container desiccants assist in complying with these regulations by helping in maintaining the prescribed moisture levels. Compliance not only ensures the safety and quality of goods but also avoids potential legal issues or delays in customs clearance.
Forms and types of desiccants used in supply chain
Transportation containers made of desiccants that are available in a wide variety, provide versatile protection against moisture and humidity damage during transit. They come in bags and contain a non-toxic clay desiccant mixed with a trace of calcium chloride, making them an excellent choice for transporting items such as coffee beans, canned foods, flour, rice, and many others. The following are the important forms and types of sustainable desiccants to prevent damage to transport goods and significant economic losses.
- Humi Dryer Bag: The Humi Dryer Bag is a container desiccant bag containing a toxic-free, natural clay desiccant infused with a bit of calcium chloride. It has a high vigorous absorption quality over a wide temperature range. The Humi Dryer Bag retains moisture and maintains low humidity levels, absorbing up to 80% of its weight in shipping containers. It absorbs and holds moisture inside the bag as a thick gel that will not turn into water vapour even in high-temperature environments during transit, reducing the risk of potential moisture damage to shipping goods.
- Humi Dryer Pole: The Humi Dryer Pole is a container pole desiccant manufactured from polymer gelling agent and calcium chloride designed to prevent condensation on the walls and roof of the container by decreasing the dew point and maintaining a relatively low humidity level. It can be secured either by directly hooking it to the container’s wall ring or simply placing it on the container floor. It is specially designed to fit in-between the grooves of the shipping container walls due to its pole composition, maximising shipping space while protecting cargo from water vapour by allowing moisture to enter the desiccant, where it quickly takes a gel-like structure. Also, its protective packaging inhibits condensation and leakage from temperature changes in the shipping container.
- Humi Dryer Strip: The Humi Dryer Strip is a non-toxic, natural clay desiccant mixed with a small amount of calcium chloride that works as a dehumidifier and moisture absorber inside the container or packaging. Capable of absorbing water vapour up to 80% of its weight, the Humi Dryer Strip efficiently removes moisture and lowers humidity levels in the shipping container to ensure a dry surrounding environment, protecting goods from potential moisture and humidity damage during transit and storage. The Humi Dryer Strip can either be fixed by attaching it with a hook to hang it or simply placing it in the container.
- Humi Dryer Strip Plus: The Humi Dryer Strip is also available in an advanced version – the Humi Dryer Strip Plus. The Humi Dryer Strip Plus is a specially formulated desiccant made from a calcium chloride polymer gelling agent. It is designed to inhibit condensation on the container walls and roof by lowering the dew point and reducing the humidity level inside shipping or storage containers, protecting cargo from moisture damage while shipping. Instead of a moisture absorption capacity of 80% like the Humi Dryer Strip, the Humi Dryer Strip Plus can absorb water vapours up to 280% of its weight, a considerable amount of moisture. The Strip Plus allows moisture to enter the desiccant, which takes a gel-like form, preventing container rain and assuring a dry container environment for shipping goods (Fig. 1).
- Silica Gel: Silica gel is one of the most commonly used desiccants. It is available in various forms, such as sachets, beads, or bulk, and can absorb moisture up to 40% of its own weight.
- Molecular Sieve: These desiccants have a highly porous structure and are effective at absorbing water vapour and other gases. Molecular sieves are commonly used in the petrochemical, natural gas, and oxygen generation industries.
- Calcium Chloride: Calcium chloride boasts over ten times the potency and hygroscopic properties of silica gel. Calcium chloride desiccant sucks up more moisture when the air around it is more humid. This absorption gets stronger as the humidity rises, which sets it apart from other drying agents like silica gel and clay. Supply chain usually chooses calcium chloride as the superior desiccant in their range due to its exceptional moisture-absorbing capabilities, especially in high humidity conditions, providing superior protection for products across diverse industries, including food and beverage, wood and construction.
- Clay: Montmorillonite clay, found in nature, is the best known for its capability to absorb moisture and control water capacity. It’s beneficial as it can be revived at low temperatures without significant loss of quality or increase in size. This type of clay is cost-effective, which makes it a popular choice. However, if the temperature increases, it might release some absorbed moisture. Generally, this clay is used in pharmaceutical packaging.
- Activated Alumina: Activated alumina consists of porous aluminium oxide with a large surface area, making it highly effective in adsorbing moisture and purifying liquids. It is often used in air and gas drying applications.
- Calcium Oxide: It is also known as quicklime or lime, calcium oxide is a powerful desiccant that can absorb large amounts of moisture. It is commonly used in construction and shipping industries.
Selection of proper desiccant for supply chain
Choosing the appropriate shipping container desiccant is a critical step in ensuring effective moisture control during cargo transit. The selection process requires a thoughtful consideration of various factors to match the desiccant’s capabilities with the specific requirements of the shipment. Different factors are taken into consideration while selecting the correct desiccant and determining how to use it.
- Cargo Type and Sensitivity: Different types of cargo have varying moisture sensitivity levels. For instance, electronics, pharmaceuticals, and food products are highly sensitive to moisture and require stringent moisture control. Conversely, less sensitive cargo like machinery or non-perishable goods may have lower moisture-related risks. Understanding the moisture sensitivity of the cargo is crucial in determining the desiccant’s capacity and effectiveness needed for protection (Fig. 2).
- Container Size and Volume: The size and volume of the shipping container directly impact the amount of moisture that can accumulate inside. Larger containers have more air space, which can accommodate more moisture. Smaller containers, on the other hand, may require smaller, strategically placed desiccants. Calculating the container’s internal dimensions and volume is essential for determining the desiccant quantity.
- Shipping Duration: The duration of the shipping journey can vary greatly, from a few days to several weeks or even months. Longer transit times increase the likelihood of moisture-related issues. It’s vital to select desiccants with the capacity to maintain moisture control throughout the entire journey. This may involve choosing desiccants with higher moisture-absorbing capabilities.
- Environmental Conditions: The climate and environmental conditions of both the origin and destination locations can significantly affect moisture levels within a shipping container. Consider factors like temperature, humidity, and seasonal variations. Desiccant selection should account for the expected environmental conditions during transit to ensure optimal performance (Fig. 3).
Conclusion
Desiccants, with their ability to prevent condensation, protect against humidity, thwart mold and mildew, control corrosion, and preserve product quality, act as sentinels of supply chain quality. By understanding the utility of desiccants, the logistics professionals can enhance the safety, reliability, and reputation of their shipping operations. These moisture-absorbing agents ensure that goods reach their destinations in pristine condition.
Dr. (Prof.) D.B. Jani received Ph.D. in Thermal Science (Mechanical Engineering) from Indian Institute of Technology (IIT) Roorkee. Currently he is a recognized Ph.D. Supervisor at Gujarat Technological University (GTU). Published more than 200 Research Articles in reputed International Conferences and Journals. He has also published 8 reputed books and book chapters in the area of thermal engineering. Presently, he is an Associate Professor at GEC, Dahod, Gujarat Technological University, GTU, Ahmedabad (Education Department, State of Gujarat, India). His area of research is Desiccant Cooling, ANN, TRNSYS, and Exergy.
