The number of ventilation points on ISO shipping containers varies depending on manufacturer, with the majority of units in the market place having 2 – 4 vents. Typically, vents are located at the top of the side walls and are fitted to containers to try to reduce condensation from forming on the ceiling of the unit. However, these are rather small so as not to allow water to enter the unit during shipping and therefore, don’t let a large volume of air in leading to an increased chance of condensation damaging the cargo within.
To combat this issue, our high spec range of shipping containers have 10 ventilation points and these do help increase airflow through the unit and therefore reduce the risk of condensation forming.
However, in our experience, when attempting to eliminate condensation, we recommend installing larger ventilation grilles on either side of the container to improve the volume of airflow through the unit.
If you’re experiencing problems with condensation, we sell self-fit louvre vents in a range of sizes all of which are fitted with a mesh backing to prevent rodents getting in and damaging your cargo. Our most popular vents are 350 x 350mm and 500 x 500mm but, we do have other sizes available.
Whilst fitting additional vents, please also consider what you are storing because this can have an adverse effect on the moisture levels. Items such as paper, books and even ‘green’ pallets can give off a lot of moisture. In instances such as this, we’d recommend using a desiccant to absorb moisture from the air and whenever possible, make use of plastic pallets instead of wooded ones. The shipping industry has pallets made on a near just-in-time basis and because of this, the wood does not have sufficient time to dry out properly.
Our range of desiccants include products such as Sea Dry Cargo Hooks, Absorpoles and Bone Dry Dampsticks. All of which have excellent moisture absorbing capabilities. In the short-term, desiccants offer a solution to the problem of excess moisture however, in the long term this option is less attractive due to the cost. For longer condensation prevention, we recommend having the industry standard coating (Grafo-Therm) applied to the ceiling of the container.
Grafo-Therm absorbs about 1 litre of moisture per square metre (based on a coating thickness of 1.5mm) and then as the ceiling warms up through the day, this moisture is then safely released back in to the atmosphere and out of the unit through the ventilation grilles.
Which option you choose is very much dependent on what type of cargo you are storing.