This was key to the launch of the British Compressed Air Society (BCAS) free best practice guide around three years ago, designed to help operators and specifiers make an informed choice on which type of compressed air treatment equipment is best suited to the air quality required.

Since then, operators have found the Filtration and Drying of Compressed Air guide an invaluable tool, offering practical advice on which contaminants can be present and their impact on the processes that compressed air is being used for.

Reliable technical information

We caught up with Roy Brooks, technical development officer at BCAS to find out about some of the latest developments in the world of compressed air filtration and drying.

"At BCAS, we act as an independent and reliable source of technical information for the industry, providing impartial advice which can help operators cut costs, improve efficiency and ultimately profitability," he explained 

"The Filtration and Drying of Compressed Air guide was designed to assist during the entire specification process, covering all stages of system design; from an overview of the sources of contamination, such as solid particles, water, and oil, to the relevant standards for air purity.  It also examines the extensive range of air purification technologies available and how these operate, including after-cooling, dryers, air receivers, filtration grades and condensate management.

"With compressed air energy costs now a major contributing factor to a site’s overall electricity consumption, the guide also focuses on the varying energy efficiencies of the different treatment technologies available as well as guidance on the ongoing maintenance of the system.

"Not long after we first published the guide, the Coronavirus pandemic really started to impact on productivity, and we had many enquiries from end-users."

A key concern was whether their compressed air supply was adequately protected and that there can be no risk from airbourne contaminants. The following information provided at the time, is still highly relevant when designing a system to ensure the correct levels of air quality (purity).

Managing contaminants

Air compressors draw in micro-organisms as solid particles contained within ambient air, first through panel filters and then through intake filters. These micro-organisms consist of viruses, pathogenic bacteria, moulds and fungi, which, if left untreated, can survive as spores with the potential to grow in the downstream compressed air.  

Therefore, the installation of appropriate inline coalescing filtration and its regular maintenance are essential, as these will remove multiple contaminants including micro-organisms, oil and water aerosols.

Ambient air contaminants would have to remain in aerosol form to pass through panel and intake filters in order to enter the compressor intake. This is highly unlikely, but even if panel and intake filtration was compromised, the contaminant would not remain in aerosol form during compression and therefore, would present no danger.  

This is because during compression, the air temperature is high (in excess of 120oC) and the heating time is short, meaning that viruses do not tend to survive the compression process.

BCAS Best Practice Guideline 102

To help avoid any contamination issues, BCAS advocates following Best Practice Guideline 102, in particular the specification for direct contact applications.  

The best practice guidance (BPG102) is designed to help processors make informed decisions relating to compressor systems operating at a pressure greater than 0.5 bar. 

The guide is available for free download from the BCAS website. This guidance recommends using a dewpoint of -40 degrees C to inhibit the growth of micro-organisms, and filtration to reduce the micro-organisms and particulate.

The specification requires the installation of a minimum of two aerosol reduction filters (down to 0.01mg/m3 of oil aerosol and particle reduction down to 0.01 micron).

These protective measures will ensure that, should a virus still survive the heat of compression, aerosol reduction filters in the compressor room combined with a very low dewpoint and point-of-use dry particulate filters will remove any risk from compressed air.

Printed copies of the guide are available from BCAS for £4.00 each plus postage by emailing [email protected]

www.bcas.org.uk

Tel: 020 7935 2464