Dry air storage is the name of a non-heated storage room with a dehumidification installation. At the same time non-heated means that the temperature indoors is close to the temperature outdoors – and at Danish conditions, i.e. with low temperatures during the wintertime, the use of an adsorption dehumidifier is the only serviceable alternative, this due to its wide area of function.

If at storage and warehousing of goods (paper, textiles, furniture, steel products, ammunition, etc.) you do not provide a sufficiently low level of humidity, you risk that the goods get damaged e.g. with great loss of value as a result.

Only few materials tolerate the exposition to high atmospheric humidity for a longer period of time. Most of them will be ruined. Examples are: iron will corrode, salt and fertilizers will get lumpy, wood and textiles will go mouldy and rot, cardboard boxes will lose their firmness and sustainability.

Often the limit for the risk of damage from humidity is around 55-60%RH. If further free water is present (condensation on cold surfaces) the decomposition will take place more quickly.

In storage rooms the humidity comes from outside. If no heating or dehumidification takes place, you will have the same atmospheric humidity inside and outside, and the humidity of the outside air in Denmark lies on an average of approx. 85%RH – the highest value during the wintertime.

Traditionally, you have two possibilities for decreasing the atmospheric humidity: Heating and Dehumidification.

Heating:

Heating may be a good as well as efficient way of preventing damage from humidity. If the room (and thereby the air) is being heated, the air will be able to retain more water, and the relative humidity will decrese.

However, heating asks for a well-insulated building in order to meet the demands of building rules and regulations and in order to keep down the cost of energy. Additionally, the installation of a heating system is needed. If you heat the room for a constant temperature of 20°C, the relative humidity will fluctuate correspondingly throughout the year, i.e. from 20%RH during the wintertime and up to 80%RH during the summertime, where no heating takes place. The fluctuation in %RH itself may be damaging to certain materials. Even so, heating may in many cases represent a good and necessary solution.

Dehumidification:

Usually materials do not have special demands for temperature, but only for the humidity of the air. Consequently, an installation of a dehumidification system, that will maintain a constant relative humidity all year round, is the right solution in consideration of the materials.

And there are further good arguments for such an installation:

• Saving of energy compared with heating
• The installation of a dehumidification system is usually more simple and economic than the equivalent installation of a heating system
• No need for insulation of the hall
• A building is usually easy to proof, a fact being the only demand for the installation of a dehumidification system
• Simple halls, such as e.g. tents, may be used if only they are diffusion-proof and the jointing is proof
• The saving of energy when using dehumidification compared to heating is approx. 60%.

HBC adsorption dehumidifiers are used for the following types of dry-air storage rooms:

• Military ammunition magazines, stores, warehouses
• Storage of seed grain Industrial storehouses, automatic storage
• Storage of raw materials containing steel
• Storage of furniture
• In containers
• In the cargo compartments of vessels