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What are Desiccants?

11/8/2013 7:51:53 AM | by Anonymous

Desiccants

Desiccants are hygroscopic substances that draw in moisture from their surrounding environment or induce a state of dryness in its vicinity. There are a number of uses for desiccants. They range from preparing the chemicals in a chemical plant in order to protect the moisture sensitive items during the shipment. Some common desiccants would include sodium perchlorate, activated carbon, silica gel and calcium sulfate. Salt and rice are also both common desiccants used around the house. They have been used for their desiccating properties by many cultures historically. Salt for instance was a key component used in the mummification in Egypt. They use it to draw the water out of the bodies to reduce the speed of the rate of decay or even to completely stop the decay from happening. For industrial uses, desiccants are widely used to control the level of water in the gas streams.

 

Dryness is often a largely sought after desired property. Many objects are allowed to dry through evaporation however the water loss slows as the evaporation reduces the moisture content of the object that of the surrounding environment. Once an object is as moist as the surrounding environment, it no longer has the means to lose any more water. Thus, this is where desiccants come in useful. It encloses the object in a container with a desiccant that will allow it to lose more water as the desiccant sucks the fluid out.

 

Due to their common use in preservation, desiccants are chemically stable or inert. A number of them have been identified and are in common use. The two types of desiccants are those that are for performance efficiency and for coloured saturation indicators. One measure of desiccant efficiency is the ratio of water that is storable in the desiccant relative to the mass of the desiccant. Another measure is the residual humidity of the air or fluid that is being died. Another type of desiccant is that it has a humidity indicator included in it to show by the colour changes, the degree of water saturation of the dessicant. One commonly used indicator is the cobalt chloride. The anhydrous cobalt chloride is blue when it bonds with paper, it changes to purple.

 

One of the common uses for desiccants is in the shipment of goods. This is where things may get damaged when they come into contact with water or become moist. Desiccants are also included in the packaging to help draw the excess water out. They can be discarded once the objects have arrived at their destination for use. These products are also typically used in dehumidifiers. They bring down the moisture in the air by drawing in the water. Desiccant cooling systems also take advantages of this useful train to lower the humidity in order to make the warm temperatures feel less extreme than it really is.

 

On top of being drying, desiccants also have many other properties. Some are antimicrobial, antiviral, antifungal which makes them extremely useful for the variety of applications. Many of which are not safe for consumption and have labels placed to warn people not to get confused. Some are treated with materials that will possible stain as the desiccants attract water. This allows people to see when the maximum amount of water has been absorbed.

 

In some cases, a desiccant sachet or bag can be refreshed for use again by heating it to forcefully release the water in it. This allows them to reuse the desiccant bags to prevent wastage. Some others are of single uses only. They are needed to be discarded once they have fulfilled their function accordingly. It is always important to select the desiccant which is appropriate to the task. This is because most people want to avoid chemical reactions, corrosion and other problems that may occur due to the wrong substance being used as the desiccants. Examples would be like salt. It cause metal corrosion which then makes it unsuitable for the settings wherever metal is present. Thus, it is important to be aware of what substances are not suitable to another.

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