Compressed air dryers are an important addition to air compressors and allow particles such as oil and water vapour to be safely removed.

Filtering and drying compressed air can reduce the chances of corrosion and other issues, improving the life of equipment and reducing the need for maintenance.

Many air dryer types can effectively remove contaminants and water vapour, producing quality compressed air which is suitable for sensitive applications. Air dryer types include membrane, desiccant, deliquescent and refrigerated air compressor dryers.

What is an air compressor dryer?

Air compressor dryers use a number of different methods to remove moisture and water vapour from compressed air, depending on the air dryer types. Each type of air dryer has its own advantages and disadvantages which can make them more appropriate for certain situations.

The amount of water vapour in air is measured as its ‘dew point’. The lower the temperature of air’s dew point, the less water vapour it contains and the drier it is. While some air dryer types can remove almost all the water vapour in air, lowering dew point becomes increasingly more expensive and difficult as water vapour is removed.

Refrigerated compressed air dryers

Refrigerated dryers are a popular compressed air dryer type as they are the most cost-effective to own and operate. Refrigerated air dryers work by cooling compressed air down until the water vapour condenses into a liquid form, which is then drained away.

Refrigerated dryers are the best choice to dry air for general purposes, as they remove the largest amount of water with the least amount of energy use. This can greatly reduce the problems associated with wet compressed air without spending more resources to completely remove water vapour.

Pros: Cost efficient
Cons: Does not completely remove moisture

Membrane compressed air dryers

Membrane dryers work by shifting pressurised air through a fine membrane. This membrane is designed to let water molecules pass but traps larger air molecules. This effectively separates water vapour from the air and dries it. A small amount of compressed air is then recycled into the system to eject the separated water vapour and reset the membrane.

Membrane dryers use up very little space and don’t require electricity to operate. Because of this they’re recommended for use in remote locations and in industries where explosions are a risk factor.

Pros: Small and effective
Cons: Expensive and eventually need replacing

Desiccant compressed air dryers

Desiccant dryers use materials which absorb water from compressed air and can then be heated up to release and remove water content. This reversible process typically occurs in two separate compartments which alternate between heating and drying.

Desiccant dryers are also known as regenerative dryers or two tower dryers because they can efficiently cycle between their two compartments, ensuring that compressed air is constantly being dried. Desiccant dryers also dry air to a very low dew point and so are best suited for delivering compressed air to sensitive applications.

Pros: Can dry compressed air effectively
Cons: Expensive to operate. Heated dryers require large amounts of electricity

Deliquescent compressed air dryers

Deliquescent materials are special compounds which attract and absorb water vapour in compressed air to form a liquid solution through their combination. Mineral salts such as calcium chloride are commonly used in deliquescent dryers.

Deliquescent dryers normally require installation of a coalescing filter before air reaches the chemical dryer. Coalescing filters work by trapping particles and water until they grow large enough to drain away, removing liquid water before it enters the dryer and helping to preserve the deliquescent material.

A particle removal filter may also be needed after the deliquescent dryer to prevent chemical particles coming through, depending on the use of the compressed air.

Pros: Dries air quickly and efficiently to a high quality
Cons: Requires daily replacement of materials and additional filters

Removing water vapour from your air compressor is essential to ensuring proper functionality and reducing the need for future maintenance and repairs. Dried compressed air can enable you to power your applications safely and efficiently without having to deal with errors and contamination.

Author Bio:

This article was written by Daniel Defendi, from Express Compressors in Perth. You can catch Daniel on Google+ to discuss this piece.