In today’s modern plants and factories, the demand for air from the compressed air lines is an important factor. Compressors, which may often be working at full capacity, utilise power which costs money. It is therefore important to minimise losses for economic and environmental reasons. All Polar Air desiccant air dryers have a purge valve system, which controls the purge in order to dry the desiccant.
Some are adjustable by hand and others have a fixed orifice. On average the air used for drying in a desiccant air dryer is between 10% – 15% of the air that is delivered from the compressor. This includes the usage of the automated pre-filter that comes as standard on Polar Air air dryers The larger units have a hand adjustable valve which should always be set to ensure that the air dryer vessel that is in purging mode does not build back pressure.
Take care not to set the purge flow too high as this will incur a greater amount of air used unnecessarily, resulting in under performance of equipment, especially if the supplying compressors are underspecified.
Smaller units come with a fixed orifice that is preset by the manufacturers to ensure the correct purge flow in relation to the air dryer size and compressor air delivery.
Another consideration is the air used if there are more pre or after filters with automated drain valves. This type of valve will open for a short time every hour draining more air from the system.
Therefore compressors and dryers should be correctly specified to compensate for this air usage, in order to provide enough compressed air to operate all areas where air may be required.