Compressed air is just that. A large volume of air at atmospheric pressure compressed to a higher pressure in a smaller space.
When we compress all that air, we also compress all its impurities along with it, dust and pollen and oil vapour – but let’s discuss water vapour and how to remove it from your compressed air lines.
While most water separates from the air as the air cools, that separated water can still carry further down the lines causing damage to the pipes and the equipment that utilises the compressed air.
As the tools we use become more complex they also become more sensitive to the damaging effects of these impurities which is why air filtration has become a more important feature of the compressed air line in recent decades.
One such component in this filtration system is the Compressed Air Dryer.
The compressed air dryer is a feature in the air line that is designed to remove the water from the air, thus, drying the air.
The amount of water vapour remaining in the air line after the air dryer, is typically measured in terms of dew point, referring to the temperature the air must be cooled to become saturated with water.
Essentially, the lower the dew point, the less water vapour remains in the compressed air line.
This process has previously been achieved by means of the Joule-Thomson effect where the air is rapidly cooled as it travels through a valve from a higher pressure to a lower pressure vessel and draining the resulting condensed water from a low point in the system.
While this was once a suitable solution for previous applications, this process was prone to blockages due to freezing water vapour with and proving unreliable with a relatively high concentrations of water remain in the air lines as the condensed water returned to vapour before it could drain. This left the air with dew points comparable to that of ambient temperatures. This is much too high by today’s standards.
Refrigerated Air Dryers are a very cost and energy efficient means of removing water vapour from the air. By means of chilling the compressed air, the refrigerated air dryer can remove a great deal more of the water vapour from the air line.
Refrigerated air dryers typically achieve dew points between 2 - 5°C (35 - 41°F) making them suitable for more than 95% of compressed air applications. Refrigerated air dryers are limited to temperatures above freezing point to prevent blockages in the air line which can quickly cause significant loss of air pressure.
To account for the numerous variables required to assure efficiency of the refrigeration system, many of the internal features can be somewhat complex and sensitive to wear and small changes in the features of the air inputs. These internal parts may develop issues that - if not caught early and adjusted - may cause catastrophic failure of the unit. Therefore, it is recommended to regularly monitor and periodically service your refrigerated air dryer by a professional technician.
Regenerative Desiccant Compressed Air Dryers are far more effective at removing water vapour from the air by utilising an adsorption method of air drying. This method removes the limitations caused by freezing water, allowing for typical dew points of -40°C and as low as -80°C. These extremely low dew points are typically required for specialised applications such as medical laboratories, pharmaceutical production, precision equipment production, computer component production and much more.
While effective, the regenerative system is not the most efficient with a typical air loss of 15% during the purge cycle. This, however, can be reduced at the cost of an added heating element.
With over 40 years of combined experience, AU Dryers Australia Pty. Ltd., specialises in compressed air drying units and can provide you with the right information and the right air drying unit for your system. Contact us today using the information request form here.