Humidity in shipping containers

4755759101 a3f3672583 m Humidity in shipping containers

1. 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.

2. When stuffing a container in any climate, you also stuff the actual humidity contained in the air at the place of packing.

3. When closing the container, the humidity is contained in a very small space. As the container is moved from one climate to another, the humidity vaporizes up into the ceiling of the container, where it will start to rain down onto the cargo. Either the humidity will start to soak into the cargo or run along the surface of i e steel products. It can also turn into water that runs towards the bottom of the container. Nordic Container Desiccant actually “catches” the moisture before it vaporizes.

150x98 Humidity in shipping containers

4. As soon as the climate changes, the moisture will either vaporize again or really start making trouble among your different products being shipped, if you do not use a desiccant. The longer the transportation time – the more damage may possibly develop.

5. You may have seen your cargo being loaded in perfect condition. But have you ever opened a container full of molded furniture? Or rusty motor equipment? Or rice sacks full of mildew? Or fruit covered in fungus? The customers do not like it. They will blame you. They will lose money and time, they will lose their customers and they will make claims to you. Then you will lose money and time, and possibly even the client. Since there are many parties along the transportation chain, many may be blamed for damaged goods – like manufacturers, traders, shipping lines and forwarders. Why be among them?

6575830877 1ba400f59f m Humidity in shipping containers

Container ships at the Port of Oakland (Photo credit: mental.masala)

6. Other desiccants being used are i.e. silica gel. Silica gel is the most common type of desiccant in use today. It is a porous sand and can absorb moisture in the air, often up to 40 % of it´s weight. However, silica gel absorbs moisture best in small, confined spaces and often end up getting saturated in a very short time span, making it unsuitable for container shipments. When saturated, it will not help catching the moisture anymore. Be aware that some silica gel – the blue contains cobolt – is toxic, and can not be disposed of any which way.

7. The best insurance there is – using Nordic Power Desiccants. The effect is 40 – 60 % better than other products in the market.

 

Call for more information: 02-707 9884

 


CleanPrintBtn gray small Humidity in shipping containersPdfBtn gray small Humidity in shipping containersEmailBtn gray small Humidity in shipping containers

InterDry Power Desiccant – Frequently Asked Questions:

1. How does InterDry Power Desiccant 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 InterDry 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 InterDry, will I have any more moisture problems?

InterDry 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.
  • 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.

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 InterDry absorbs a few liters moisture during a voyage?

InterDry 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 InterDry?

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 InterDry 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 InterDry 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 InterDry 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 InterDry absorbs the moisture in that air and prevents condensation.

19. I have problems with mold growth inside my shrink-wrapped pallets. Will InterDry 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 InterDry 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 InterDry Power Desiccants?

InterDry 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 InterDry?

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 InterDry or not?

There is not much difference between those containers, so you don’t have to adjust the number of units.

 InterDry Power Desiccant   Frequently Asked Questions:

CleanPrintBtn gray small InterDry Power Desiccant   Frequently Asked Questions:PdfBtn gray small InterDry Power Desiccant   Frequently Asked Questions:EmailBtn gray small InterDry Power Desiccant   Frequently Asked Questions:

Is the colour of a shipping container important?

By: Pakarada Premtitikul
General Manager
InterDry (Thailand) Co., Ltd.

Does the colour of a shipping container affect the relative humidity inside?

Steel is currently the most used in the construction of containers despite its poor insulation properties. This is because it is cheap in production and maintenance. Another factor is that it is very suitable to absorb the mechanical forces acting on a container. The colour of the paint on the exterior of the container has an impact on the internal container temperature during sunlight. For a better picture of the impact on the container I will show you two colour charts reflecting the temperature changes in a white and a brown container during the course of one day.

The chart below shows the temperature in different places within a white container and outside each hour of the day. The temperature varies between 40 ° C near the roof and 28 ° C near the floor with an outside temperature of about 28 ° C at noon. During the night, the temperature of the air in the container is about 12 ° C at an outside temperature of 15 ° C.

whitecontainer thumb Is the colour of a shipping container important?
Figure 1: The temperature at different places in a white container at every hour of the day.

A similar study was done with a container with a brown color. There were much higher temperature differences measured. A measurement at midday found a temperature of about 50 ° C near the roof and 35 ° C near the container floor with an outside temperature of 25 ° C.

During the night the air inside and outside the container had similar temperatures, fluctuating around 15 ° C. These measurements are in the chart below

browncontainer thumb Is the colour of a shipping container important?
Figure 2: The temperature at different places in a brown container at every hour of the day.

The colour of a container indeed affects the internal temperature. Previous charts showed that a dark container has a temperature increase of about 10 ° C more with the same outdoor temperature (27 to 28 ° C). The relative humidity can change from 80% for example to about 50% which can cause a great hygroscopic imbalance. It also comes with a larger cooling. All the humidity extracted from the goods into the container internal air to balance the hygroscopic imbalance due to the temperature rise in the afternoon will condensate during the drastic drop in temperature in the evening.

The figure below shows an estimate of the occurrence of certain container colour. This estimate resulted from the assumption that the size of the container capacity of 10 major container liners is approximately equivalent to the size of the total number of containers that are transported. And that the container liners only transport using their own containers. Even though bright colours like white, gray and yellow are popular, darker colours like dark blue and even green are also relatively common.

containercolours thumb Is the colour of a shipping container important?

Figure 3: Percentage of container colour occurrence.

 Is the colour of a shipping container important?

CleanPrintBtn gray small Is the colour of a shipping container important?PdfBtn gray small Is the colour of a shipping container important?EmailBtn gray small Is the colour of a shipping container important?