Seal the container vents — and stay in control 

Should a shipping container be well ventilated to minimize moisture damage and prevent mould and mildew or corrosion to metal goods? Most people would automatically say yes. We’ve all been in a musty, smelly room or basement that you need to air out. So, it’s just common sense, right?

But, when you’re looking to protect containers and their cargo through an effective desiccant solution, leaving the vents open is the wrong approach. At Absortech, we recommend that you should seal the container vents by taping over them on the inside of the container — helping you stay in control, confident that your desiccant solution is correctly dimensioned and will deliver the intended protection.

Less air = less moisture

By sealing the vents, you have more control of the container interior and humidity. Just as your desiccant solution looks to maintain a lower RH and prevent moisture damage, sealing the vents supports the same goal by minimizing the amount of new, humid air entering the container and reducing the overall risk to your cargo.

Of course, this does not mean that the container is 100% sealed and airtight. So you won’t avoid the daily cycle of container breathing where air expands and moves out of the container as the temperature rises in the day and new air moves in when the temperature drops at night. But sealing the vents — and even going a step further and taping the doors — will improve the underlying conditions and reduce the new air entering the container outside of these temperature variations.

Tested in the real world

Recently, Absortech carried out a field test for a customer shipping unplugged reefers that do not have the ability to hold temperature or humidity. Since the reefers were unplugged, we recommended closing the vents and using desiccants inside the container.

The graph below clearly shows how effective the desiccants are when they can operate within a sealed space. The relative humidity was lowered down to 25% even though there was evaporation of moisture from the goods.

%RH inside container with sealed vents and inside packaging

We’re here to help

At Absortech, we recommend closing or taping the vents as part of your moisture damage prevention plan. But do not hesitate to get in touch to explore your options and confirm the most effective and driest solution for you and your cargo.