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1. How does Nordic Power Desiccants help solve moisture problems?
This unique product absorbs moisture by extracting water vapor present in the air, thus preventing the humidity inside the container from reaching dew point and condensing. The desiccant then starts to turn into a gel as it continues to absorb moisture. The water absorbed is retained due to the presence of a special binding agent, thus preventing it from leaking. Lower relative humidity Nordic controls the humidity inside containers by preventing the air from reaching dew point and condensing, thus protecting your precious cargo.
2. What is Relative Humidity (RH)?
Relative humidity measures the amount of moisture in the air. It is expressed in a percentage of how much moisture the air could possibly hold. The wetter or damper the air is, the higher the relative humidity. The drier the air feels, the lower the relative humidity. Thus, 100% humidity is actually rain.
3. What are the most common problems caused by moisture?
Moisture in containers causes problems such as mold, fungus, mildew, rust decay, lumping, caking, agglomeration, and decomposition. Moisture can also cause electronics to malfunction.
4. Is moisture damage always instantly visible when handling the cargo?
Unfortunately not. Though common forms of moisture problems such as corrosion, mold, or fungus are visible on the cartons, surfaces etc there are some kinds of damage that is not visible.
Mostly these damages are internal and visible only when the customer opens the shipments. In the case of devices, they often cease to function the way they should.
5. I fumigate my containers; do I still need to put in desiccants?
Fumigation and using desiccants have two different purposes and are not alternatives to protect your goods against moisture damage. Fumigation is primarily to eliminate insects and eggs in the container and in the goods. It has no influence on the humidity inside a container. Desiccants will not influence the effects of fumigation and can easily be put in before or after fumigation.
6. If I use Nordic, will I have any more moisture problems?
Nordic Prevents Moisture damage by controlling the Relative humidity and indeed prevents those problems. However, the ventilation holes in the container need to be closed and the number of units to be put in a container needs to be adjusted to the situation.
7. I load my container under dry conditions and it is very tightly sealed. How come I still experience moisture problems?
If there are still moisture problems, we can easily say that the number of units per containers currently is not sufficient and it is advisable to increase the units per container. There are many factors for bigger amounts of moisture inside the container.
Examples of those factors are:
Container Floor: Recent studies carried out by R&D department, proved that the moisture content of the wooden floors is higher than they used to be. That is partly because of the quality of the wood that is being used nowadays and partly because the floors are being cleaned with water and they are not dried out enough before being used.
See also our post: http://interdry.wordpress.com/2010/10/10/does-a-container-floor-have-any-effect-on-the-relative-humidity-in-a-shipping-container/
Packaging: Wooden pallets always contain more than 20 % moisture, which always causes problems whichever products are put on the pallets. The packaging, often being cartons, contains a lot of moisture in itself, which will spread into the cargo or vaporizes into the air.
Products: The biggest factor of moisture inside a container is the products itself. The MC varies roughly spoken between 10% and 35%. When the MC reach the 25%, the cargo is in the danger zone.
Journey and climate factors: When all the above mentioned factors are controlled and there is still a problem, they surely are the conditions during transport. The first point of consideration is the transport time. It depends on the destination and more importantly the climate during shipment and final destination.
Basically, the changes in temperature and automatically the relative humidity is the cause of condensation. If long transits cannot be avoided, again our advice is to add more units to absorb the extra water molecules.
See also our post: http://interdry.wordpress.com/2012/01/27/ocean-container-temperature-and-humidity-study-2/
8. I ship consumer goods in tubes/cans/jars etc that contain no moisture, yet I still have problems.
As said before the moisture comes from the container floor, pallets, open ventilations, weather change during journey. And it will condense on the tubes/cans/jars that cause corrosion and labels to fall off.
9. Each container of my cargo of peanuts/coffee/cocoa contains tons of moisture. What difference does it make if Nordic absorbs a few liters moisture during a voyage?
Nordic absorbs the exceeding water molecules in the air and reduces the Relative Humidity inside the container, so that it will not reach the dew point.
10. Does it make a lot of difference that my cocoa beans have a moisture content of 8% instead of 7%?
One percent more or less doesn’t make a difference, especially not when the MC is on the lower side.
11. My cargo of peanuts had suffered damage in the centre even though the outside of the cargo looked fine and there were no signs of condensation. Why?
Condensation on the surface of your cargos can evaporate quickly, but it takes more time for the moisture which gets
trapped deeper. Before it evaporates back to the air, mold and fungus would have already grown.
12. How does Silica gel works?
Silica gel is the most common type of desiccant in use today. It is porous sand and can absorb moisture in the air. However, silica gel absorbs moisture best in small, confined spaces and often ends up getting saturated in a very short time span, making them unsuitable for container shipments. Beware that some silica gel – the blue contains cobalt – is toxic, and cannot be disposed of any which way.
13. Do I still need to use silica gel in my boxes?
It is definitely not a bad idea to use sachets of silica where the air is tight, and moisture is trapped, like in boxes and items packed in plastics.
14. My Cargo was damaged even though I used a lot of silica gel and there was no condensation. Would it help to switch to Nordic?
Perhaps there was not enough Silica Gel put inside the container. You need about 40Kg Silica Gel for a 20″ container. I can assure you a better result with Nordic Power Desiccants. Silica works pretty well in smaller closed spaces, like shoeboxes. It absorbs very quickly and is often already saturated before the container is moved.
15. What is so great about Nordic anyway?
We have superb products that actually reduce the RH inside the container. When it absorbs moisture, the powder base will change into a gel. It is more efficient and safe in use. Even when the product gets damaged, it will not spill any water on the goods. It is easy, safe, and inexpensive solution for the problems with moisture damage.
16. How many units must be put in one container?
That depends on many things. The container size, the cargo, moisture of cargo, moisture of container’s floor, moisture of pallets, length of journey, and weather during journey and so on.
An example: a 20 feet container with KD (Kiln Dried) furniture needs 4 units, while 20″ air dried furniture needs 6 units. We generally offer expert advice regarding optimum usage of the desiccants for best results.
17. Do I need to line my container with Kraft paper?
Sweat or Kraft paper is a commonly used method of containing “rainfall” that occurs inside a container. Normally it is installed under the ceiling to absorb the moisture that may occur due to container rain. It is most useful while shipping goods that have very high moisture condensation, but it cannot replace a desiccant that soaks up the humidity before it even turns into rain.
18. My containers are stuffed till the top. Can Nordic still be useful?
It seems that there is almost no free air in the container, while there is actually a lot of free air between the products, and Nordic absorbs the moisture in that air and prevents condensation.
19. I have problems with mold growth inside my shrink-wrapped pallets. Will Nordic help?
No, unless you make holes so the water molecules won’t get trapped.
20. My shipment of steel/galvanized components, aluminum, machinery etc. arrives corroded, stained or discolored, despite heavy packaging. Will Nordic help?
Yes, as long as you put enough units per containers and do not wrap the items in plastic.
21. Can I re-use my Nordic Power Desiccants?
Nordic Power Desiccants are one-time usable, environmental neutral and disposable as normal waste.
22. My cargoes are outdoor furniture with brass parts on it. When the goods arrive at the destination, the wooden part is in perfect condition but the brass part has slight stains on it. What should I do to avoid this? Should I use more units of Nordic?
In some cases, it can happen. I can suggest adding one or two more units and wrapping it properly with only single face carton.
23. I notice that two kinds of containers available in the market right now, which are steel and aluminum types. If I shipped the same commodity inside of steel and aluminum containers should I used same numbers of Nordic or not?
There is not much difference between those containers, so you don’t have to adjust the number of units.
By: Pakarada Premtitikul
InterDry (Thailand) Co., Ltd.
Let’s have a look at three commonly used shipping routes and what this does to the temperature and humidity inside the shipping container.
We’ve chosen three routes, namely Japan – Netherlands, Japan – Memphis and Japan – Portland.
A normal shipment consists of three distinct stages. The first stage includes the time from container filling until the container is loaded onto a ship. This includes road transportation and brief periods of storage. Daily cycles of temperature and humidity are common. For example, figure 2 includes temperature swings of 40° F [22°C] during the first stage of a shipment from Japan to The Netherlands.
The second stage is the actual time at sea or aboard a ship. This may or may not be the longest stage during the container’s journey. During this stage, daily cycles of temperature and humidity are usually very minor or completely non-existent. Temperature changes are gradual, often occurring over days rather than hours. Occasionally, a single temperature/ humidity cycle occurs as the ship makes stops along the route, however extreme conditions are rare. Figure 3 includes a slow temperature rise and fall as a winter route takes the ship near the equator and then north to The Netherlands.
The final stage begins when the container is removed from the ship and continues until the recorder is removed during the freight unloading process. This may include varying periods of time spent in customs, on trains, on trucks, and in storage. Daily temperature and humidity cycles are common and may be extreme.
Typical summer shipment – Japan to the Netherlands
Typical winter shipment – Japan to the Netherlands
Some of the most interesting recordings are the extreme conditions. The highest recorded temperature occurred on July 25, 2005 during a shipment from Japan to Memphis. The temperature reached 135° F [57° C] during the third stage of this shipment (figure 7).
Hottest shipment 135°F (57°C) – Japan to Memphis (USA).
Coldest shipment -21°F (-29° C) – Japan to Memphis (USA).
The lowest recorded temperature occurred on January 15, 2005 also along the Japan to Memphis route (figure 8). The temperature dropped to -21° F [-29° C], which is slightly beyond the recorder’s published temperature range.
The shipment with the highest relative humidity occurred during a trip from Japan to Portland. The relative humidity was recorded at 96% on August 5, 2005 while the container was on land. Figure 6 shows the detailed temperature and humidity profile. The most extreme humidity conditions are seen during periods of large daily temperature changes. In this example, as the temperature slowly drops from 88° F [31° C] to 67° F [19° C] over 9 days, the humidity increases to 88% before returning to 79%. However, starting on August 4 as the temperature dropped from 121° F [49° C] to 68° F [20° C] over a 16 hour period, the relative humidity rose from 32% to 96%. The corrugated boxes seem to absorb moisture fast enough to temper humidity during slow changes in temperature while at sea. However, rapid temperature changes seen on land seem to exceed the rate at which the corrugated boxes can absorb moisture.
Highest relative humidity 96% – Japan to Portland (USA).
Be sure to check out the following page for more information on how desiccants can save your valuable cargo:
Image via Wikipedia
Its ability to absorb moisture makes it useful in several commercial applications. It is used as a desiccant, a drying agent, to prevent liquids from freezing, in salt water aquariums and in fire-extinguishers…
Sea Containers are an economical and safe way of shipping almost any kind of cargo. But putting a cargo into a closed strong box also entails a constant risk of moisture damage for every kind of cargo on every voyage.
By: Pakarada Premtitikul
InterDry (Thailand) Co., Ltd.
In this experiment, a piece of plywood, used for container flooring at MSC, was conditioned at 23 ° C and 50% relative humidity. The piece of wood was placed in a climate test cabinet at 45 ° C and 75% RH where the wood absorbs moisture. Every day the wood was weighed and the moisture content of the wood was determined. With this procedure we have more knowledge about the speed at which wood reaches its hygroscopic balance.
The wood was protected with tape in places where in reality it is not subjected to the internal container air. Following pictures show how the wood was protected.
The initial mass of the wood was 3259g. Following graphs show the results of the test. The first chart shows the mass of absorbed moisture per day. The second chart shows the increase in the moisture content of wood per day.
Unfortunately, the hygroscopic equilibrium had not been reached before the trial was stopped. The moisture content remained almost constant after 3 days. Yet the wood continued absorbing moisture. Since it is plywood, that means that once the moisture content of the top layer remains constant, the moisture will move to the lower layers of wood.
In order to see the difference between climate change and the change in the moisture content of the container floor in a container with a desiccant and a container without desiccant, the following experiment was made.
Two containers at MSC were used for this test. One container (container U6472633 MSC) was provided with desiccant and the other container (U1089745 MSC) was left as it was. The ventilation holes in the two containers were sealed with tape.
A data logger was used in both containers to measure the changing climatic conditions. In container U6472633 MSC a probe was placed near the ceiling and a probe on the floor. In container U1089745 MSC a probe was mounted on the ceiling and a probe on the outside of the door to measure the outdoor conditions. Following figure shows the positions of the probes of logger 56,844 in container MSC U6472633 and logger 56,845 in container U1089745.
Before the container doors were closed, the moisture content of the floors were measured. Following figure shows the moisture content of the container floor at various locations in the two containers before the start of the trial.
The test was performed over a period of 28 days at the port of Antwerp, and below are the results of the data loggers.
The purple curve and the green curve are respectively the relative humidity near the ceiling and the relative humidity near the container floor.
It can clearly be seen that fluctuations in relative humidity in the vicinity of the ceiling are much higher than those in the vicinity of the floor.
The purple curve shows maxima of 85% and 90% and minima of 30% and 40%. The green curve shows maxima of 70% and 75% and minima of 55% and 60%.
The blue curve and red curve are respectively the temperature near the ceiling and the temperature near the floor.
The fluctuations near the ceiling were slightly larger than those near the floor. The minima of both are roughly equal at about 10° C. The maximum temperature at the ceiling was about 40 ° C and at the floor approximately 30° C.
The purple curve and the green curve are respectively the relative humidity near the ceiling and the relative humidity outside the container.
The fluctuations of relative humidity are not comparable because outside the container it was sometimes larger and sometimes smaller.
The blue curve and red curve are respectively the temperature near the ceiling and the temperature outside the container. Minima are comparable, but the maxima showed extreme differences. The maximum temperature at the ceiling was about 40 ° C and outside about 30 ° C.
For a better comparison between the climate of both containers, the temperature changes and changes in the relative humidity near the ceiling are shown in the figure below.
The temperatures were almost exactly the same. The relative humidity, however, showed some differences. The relative humidity in the container with the desiccant showed smaller maxima.
The explanation lies in the fact that an amount of moisture was absorbed by the desiccant resulting in less moisture in the air, resulting in a lower relative humidity.
After weighing the desiccant, it was discovered that a total of 4.465 kg of moisture was absorbed. Since the air in a container itself contains little moisture, this must have been moisture from the floor. The desiccant always causes a lower relative humidity in the air so the floor was looking for a new hygroscopic equilibrium. Therefore, the moisture of the floor in the container with desiccant should have dropped as well. Next figure shows that this indeed is correct.
There are so many variables to be taken into consideration that it is practically impossible to determine a precise figure on the number of desiccant needed within a container.
Nevertheless, significant conclusions can be made such as the fact that a container floor is one of the main sources of humidity.
Desiccant always absorb more at higher temperatures and higher relative humidity. High relative humidity provides a high absorption capacity, while a high temperature results in faster moisture absorption.
If the packing unit increases in mass, the rate of absorption decreases, but the active absorption time increases.
When comparing the different desiccant products two main groups are distinguished by their absorption properties, namely the rapid absorbers and those with a long effective absorption time. If a rapid moisture-absorption is desired, for example for a shorter sea voyage, the first group of desiccants holds perhaps the greatest advantage. If a constant fluid intake is desired, the second group is the most desirable.
As the products that continue to absorb also the ones that absorb the most, fewer units are needed for this type of desiccant which is a big advantage. It should be noted that the desiccants with faster absorption, are the clay based desiccants. The desiccants that ultimately absorb the most are the desiccant based on salt.
From the test at MSC can be concluded that desiccants work. Products succeed in absorbing the moisture from the wood to bring down the relative humidity in the air. Because the relative humidity is lower, a new hygroscopic equilibrium needs to be created. In the MSC container was that new hygroscopic equilibrium was created by the wooden floor expelling moisture.
Finally, it should be noted that the choice of desiccant is not easy, but it is determined by a diverse range of interacting conditions such as type of cargo to be shipped, the length of the voyage, the sea route, the season the container is transported and so on.