COMPRESSORS & COMPRESSED AIR FEATURE AN AFFORDABLE ALTERNATIVE TO OIL-FREE result in contamination. BOGE offers a


wide choice of both oil-flooded and oil- free compressors, and stresses that either category can supply oil-free compressed air when deployed in a suitable system. Oil needs to be dealt with, even if the


compressor itself is oil-free, as it is present as hydrocarbon vapour in the air all around us. Along with the hydrocarbons produced by burning of fuels, there are others released by substances such as paints and solvents. Although their concentration may be


With the food and drink sector’s need to avoid contamination in mind, Mark Whitmore of BOGE Compressors, offers some advice on effective ways of keeping compressed air clean


B


ritain’s food and beverage industry accounts for 19% of the country’s total


manufacturing, with a turnover of £97.3 billion, according to the consultancy BDO. While this should be reflected in high profitability, companies often lose a substantial proportion of their profits through costs relating to product contamination. Recall and disposal of stock is expensive, and may be compounded by reputational damage, loss of sales and claims for compensation. Compressed air, powering many vital


functions in this industry’s manufacturing and processing plants, can pose a major threat if it becomes contaminated. There is potential for its contact with food and drink products in systems used for handling, cooling, freezing, labelling, cutting, peeling, bottle filling, packaging and more. Contaminants in compressed air can


make a product unfit for consumption by affecting its taste, appearance and colour, as well as reducing its shelf life and compromising its hygiene. This is a serious issue for an industry where consumer and employee health is protected by tight controls and legislation. Food and beverage companies should


include measures to avoid contamination of compressed air in their Hazard Analysis and Critical Control Points (HACCP) plans. The publication ‘BCAS Food Grade Compressed Air Best Practice Guideline 102’ sets out a voluntary code of practice agreed by the British Compressed Air Society (BCAS) and British Retail Consortium (BRC). It gives specific guidance on what type of compressed air equipment can be used and how it should be installed, maintained and audited.


 The BCAS and BRC code gives


recommendations on the levels of air purity needed to keep contamination risks from dirt, water, microorganisms and oil to a minimum. Compressed air users should also be aware of the international standard ISO 8573-1: 2010, which covers a range of contaminants and air purity classifications. There are three main sources of


contamination concern: the atmosphere, the compressor and the pipework through which compressed air is received and distributed. The contaminants fall into three interacting forms: • Solid – including dust and microbes


drawn in from the atmosphere, and particles loosened from system components by abrasion or corrosion • Liquid – including atmospheric water


pulled into the system, or condensing from vapour within it, along with compressor lubricants and coolants • Gaseous – including vaporised water,


lubricant and coolant Oil is used for lubrication and


cooling in most industrial screw compressors, but this need not


With the right


specification and advice, compressed air systems not only avoid the repercussions of contamination, but run more economically, effectively and profitably


Contaminants in compressed air can make a food product unfit for consumption, so it’s crucial that they are avoided


very low in the ambient air, they become much more concentrated when that air is taken into the system and compressed. The same happens to atmospheric water vapour and anything else suspended in the air. In short, however ‘clean’ the compressor is, it needs purification systems to remove contaminants – including oil – from the air it generates. Oil and other hydrocarbons in


compressed air are turned into carbon dioxide and water by BOGE ‘bluekat’ catalytic converters. They can be used to deliver Class O oil-free compressed air, complying with ISO 8573-1, without the need for an oil-free compressor. Compared to buying and operating oil-


free compressors or conventional treatment systems, this is a more affordable approach. It provides a reliably pure compressed air supply, regardless of the intake air quality, and there is no contaminated condensate requiring disposal. Some or all of the following treatment


methods can be combined with catalytic converters to complete the clean system: • Water separators – removing bulk


quantities of condensed water and liquid oil • Coalescing filters – extracting water or


oil which has formed an aerosol of small droplets • Drying systems – reducing air humidity


by use of refrigeration, pressure-over- generation, membrane or adsorption (desiccant) dryers • Dust removal filters – capturing dry


particulates and other solid materials • Sterile air filters – ensuring absolute


removal of any remaining particles and microbes • Routine maintenance – cleaning and


sterilising all piping between the sterile filter and the application Protecting the health of consumers and


employees is paramount, but there are also financial incentives for using compressed air with care. In addition to their effects on people, products and business, contaminants can also damage machinery, so it’s crucial they’re avoided.


BOGE Compressors uk.boge.com/en


PROCESS & CONTROL | FEBRUARY 2020 9


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