USING ABSORBERS

USING ABSORBERS

There are three different main types of Absorbers.

• Silica Gel
• Clay or mineral absorbers
• Calcium Chloride based absorbers

They each have their different properties which make them suitable for different purposes.

Silica Gels are good absorbers at room temperature, but tend to catastrophically give up the absorbed water if the temperature gets near 40C. In our opinion they are unsuitable for use in containers where such temperatures are not uncommon.

Clay absorbers are cheap, but also have a low absorption. In moderate conditions they are an alternative, but they cannot handle more challenging circumstances.

Calcium Chloride is the most aggressive absorber. As the salt absorbs moisture from the air a saline solution – a brine – is formed. This brine needs to be handled with care. It is strongly corrosive on metals. If left exposed to the air, the brine will under some circumstances give up the moisture it as absorbed in a way that can cause great damage, in some cases even leaving a briny pool.

The Absorpole / Absorbag / Absortop product are all based on the use of high grade Calcium Chloride to aggressively remove moisture from the air. The resulting brine is collected in a container where it is safely sequestered from further contact with the air. This simple principle is the bass of superor functional properties of these products:

• A high absorption capacity. – Exactly how much moisture the salt will absorb depend on the temperature and humidity, but is often more than 100%.
  
• A high absorption rate. – When the temperature changes quickly, a lot of moisture needs to be absorbed in short time to prevent condensation from dripping onto the cargo. The rate depends on the temperature and humidity, but may reach 10g/hour or more.
  
• Self limiting at extreme events –It is good to have a high rate of absorption, but not if it means exhausting the absorber at a single extreme event. Especially not, if all that s achieved is to draw more moisture out of the cargo. The absorber needs to last the entire voyage. The geometric shape of the container and other design details makes the Absorpole self limiting n such cases. It lasts the voyage.
• The brine is safely sequestered. It will not leak out and it will not re-evaporate
• Calcium Chloride is completely non toxic and can safely be used in food shipments. The container is made of environmentally safe PE/PP plastics that can be easily re-cycled.
• The poles are easily mounted in the wall corrugation of secure hooks. The do not fall down or break.
• Absorpoles have proved successful with every type of cargo. For protective installations with the same level of protection, Absorpoles are usually cheaper than the alternatives. And ith additional advantages, besides. (see list above).

How to use Absorpoles/Absorbags

How many poles are required depends on the kind of cargo and the length and conditions of the voyage. We have a lot of experience from different cargos, and are able to make a first estimate from comparison with similar shipments. But there may turn out to be significant differences that prove the first estimate wrong.

We usually recommend that you start with some extra poles beyond what you think you need, so as not to risk your cargo on experimentation. The number can then be reduced once you have gathered some data on the voyages from feedback on damages, the amount of moisture collected in the Absorpoles and perhaps from Alfasensors and electronic loggers.

The best way to get a recommendation on the number of poles you need is to answer the questions on the “Absorpole Design Form” and let one of our Senior Experts offer their advice. Usually you can have an answer within a day or two.

However, some general figures can of course be given. Under moderate conditions (not a very long voyage, not crossing the equator etc) a 20 ft container should have.

• Dry Cargo 3-6 poles
• Moisture containing cargo (wood, paper, lots of packaging) 4-8 poles

Under more difficult conditions (long voyages, crossing the equator, long inland transports, very moist cargo etc), the above figures need to be increased by 50% or more.

A 40ft container generally requires a little less than twice a 20 ft container.

The only way to really decide what s the most economical and effective number for your cargo is to collect real data on your shipments. That you should do not only as a test, but systematically.