Moisture is the major culprit found in all compressed air systems and occurs because atmospheric water vapour, drawn in by the compressor, cools and condenses into water. Of the ten contaminants commonly found in compressed air systems, water in its three forms accounts for the majority of problems experienced and if not removed, will cause corrosion of the distribution system, blocked or frozen valves and machinery, as well as providing an ideal breeding ground for micro-organisms. Liquid water and water aerosols can be effectively removed by water separators and coalescing filters.
To remove water vapour from a compressed air system, a dryer must installed. Two main types are available, refrigeration and adsorption, with the dryness of the air being measured using Pressure Dew Point (PDP). This will invariably dictate which type of dryer is selected for use.
Refrigeration dryers cool the air and collect the condensed liquid and whilst a lot of moisture is removed, they cannot provide a PDP below 0ºC (otherwise the condensed liquid would freeze), making their +3ºC PDP delivery unsuitable for all but general purpose applications with interior piping.
By comparison, an adsorption dryer with a –40°C PDP will produce air that is almost completely free from moisture, being approximately 60 times dryer than air delivered from a refrigeration dryer.
Many critical applications require a PDP well below those offered by refrigeration dryers, for example, in applications where microorganisms cannot be tolerated, an adsorption dryer with a PDP better than –26°C should be used as not only will this totally prevent corrosion but will also inhibit microbiological growth.
In operation however, standard adsorption dryers can be energy inefficient, therefore Parker domnick hunter has developed Dewpoint Dependent Switching (DDS) an energy management system for adsorption dryers. This system constantly measures the operating parameters of the dryer, particularly the outlet PDP, and adjusts the dryer performance accordingly, to the most energy efficient drying option.
As energy prices increase, the climate change levy will begin to bite into operating budgets. However, by combining the ultra-low operating costs of the high efficiency OIL-X EVOLUTION filters with the proven DDS Energy Management System employed with the PNEUDRI range of adsorption dryers, compressed air users will not only improve the reliability of their manufacturing facility, but will also benefit from typical energy savings as high as 211,000KW per annum. This equates to an environmental saving of 91,000 Kg / CO2.
The modular PNEUDRI design also eliminates the need for complex valves and interconnecting piping, being typically 60% of the size and weight of conventional designs. Furthermore, PNEUDRI dryers can be multi-banked to meet increasing compressed air requirements, and, which allows individual banks to be isolated for maintenance work that will never interrupt the clean air supply.
Dryers for Hazardous Environments
In addition to providing compressed air dryers for standard industrial applications, Parker domnick hunter also manufactures dryers for hazardous environments such as the chemical/petrochemical and offshore oil & gas industries. Parker domnick hunter can supply fully pneumatic ATEX versions of PNEUDRI which are fully compliant to Directive 94/9/EC Group II, Category 2GD, T6 and which may be configured to suit individual customer requirements.