ACN News

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.

Colin Mander, MD of CompAir took up his role as president of the British Compressed Air Society in November 2010. Since then he has been focusing on a number of industry concerns – in particular, the increasing importance of energy reduction and the use of genuine spare parts. Here, he discusses the reasons behind the campaigns and how they are helping to improve efficiencies for compressed air users Energy – always on the agenda It is no surprise that energy reduction continues to be the key driver behind the majority of compressed air system improvements.

Stephen Riley, general manager of Beko Technologies, takes a look at some of the changes that have occurred in the world of compressed air and explains why he believes measuring devices have a key role to play in managing both the quantity and quality of compressed air. Some 30 to 40 years ago the salesperson selling compressed air generation and treatment equipment had very few tools at his disposal. Many systems were over-sized because there was no low cost means of deciding the size of the system. Educated guesswork was the order of the day.

Oil-free compressed air means…well what exactly does it mean? The output of an oil-free compressor perhaps, or it could be ISO 8753 specified with the possibility to specify something better than Class 1 for hydrocarbons. Another possibility is that compressed air is taken from a lubricated machine and treated to become ‘technically oil free’. Steve Riley of Beko Technologies outlines the pros and cons of both systems and suggests a third option – the Bekokat catalytic converter.

The origins of modern compressed air filtration can be traced back to domnick hunter in 1963, the first company to use microfibre filter media for purification applications, changing the compressed air industry forever. The OIL-X filter range was the first to fully utilise this ground breaking technology and has always been synonymous with high quality compressed air. Parker domnick hunter has continued to develop both the compressed air filter and the standards governing compressed air quality.