Product category:
General packaging materials, equipment and services
News Release from: Parker Domnick Hunter | Subject: Compressed air treatment systems
Edited by the Manufacturingtalk Editorial
Team on 01 January 2007
Easy Upgrades For Air Equipment Will
Satisfy Code
The British Compressed Air Society and British Retail Consortium Food Grade Compressed Air Code of Practice helps food manufacturers and processors by providing recommended levels of air quality.
The British Compressed Air Society (BCAS) and British Retail Consortium (BRC) Food Grade Compressed Air Code of Practice is designed to help food manufacturers and processors by providing recommended levels of air quality BCAS member, Domnick Hunter is now offering a range of compressed air treatment systems, which are independently validated to ISO standards by Lloyds Register
This article was originally published on Manufacturingtalk on 23 Aug 2005 at 8.00am (UK)
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Mark White, filter product manager, at Domnick Hunter has many years experience of compressed air purification equipment and their application, according to the company.
He said: "As with any new code of practice, manufacturers will be concerned about existing equipment and may find new product selection a minefield.
In reality, the majority of existing compressed air systems may already comply, or can be easily and cost effectively updated to satisfy this code with air treatment equipment, such as high efficiency compressed air filters and dryers." White explained the main contaminant in compressed air: "As air is compressed, large volumes of wet atmospheric air are drawn in to the compressed air system, which when cooled in storage vessels and distribution piping, condense in to liquid water, making this the major contaminant in the compressed air system.
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If this bulk water is not removed, it can lead to corrosion of the distribution system, blocked or frozen valves and machinery and can ruin finished products.
More importantly is the fact that it provides the ideal environment for the growth of micro-organisms, including bacteria." He continued: "Up to 99.9 per cent of the total liquid contamination found in a compressed air system is water and the volume of water condensed in the system is staggering.
In a typically sized manufacturing unit, a compressor and refrigeration dryer combination can produce over 100,000 litres of liquid condensate per year.
The volume of condensate increases significantly for larger compressor systems, or during operation on hot, humid days." And commenting about oil, White said that food grade compressed air does not need to be oil free, nor does it need to comply to ISO 8573.1 Class 0 and as it accounts for only 0.1 per cent of liquid contamination, it can be removed using filtration.
In describing the equipment that should be considered to meet the code of practice, White added: "Coalescing filters are probably the most important items of purification equipment in a compressed air system.
Designed to remove aerosols (droplets) of water and oil, they also have the additional benefit of removing solid particulate and micro-organisms." He further explained: "Installed in pairs, most users believe one to be an oil removal filter and the other to be a particulate filter, when in fact the first one is a general purpose filter used to protect the high efficiency filter against bulk contamination.
This dual filter installation ensures a continuous supply of high quality compressed air with low operational costs and minimal maintenance." He added that water vapour is water in a gaseous form and is removed from compressed air using a dryer, its performance being measured as pressure dewpoint because filters do not remove all contaminants.
A pressure dewpoint of less than -26 degrees C will not only prevent corrosion, it will also inhibit the growth of micro-organisms within the compressed air system and for that reason, the code of practice recommends a pressure dewpoint of - 40 degrees C, or better, for air in direct contact with food, which is only achievable with a desiccant dryer.
Refrigeration dryers are also available, however they can only achieve dewpoints down to + three degrees C and are, therefore, only used for air that will not come in to direct contact with food, he commented.
And White added a word of warning: "Desiccant and refrigeration dryers are only designed to remove water vapour, not liquid water, therefore they require coalescing filters to work effectively." White also advised: "No matter what type of compressor is installed, they all draw in large amounts of airborne contamination and, therefore, the level of air purification equipment is not dependent upon the type of compressor installed.
Adequate filtration and separation products will always be required to remove the large volume of dirty contaminated water as well as dust, rust, pipe-scale and microbiological contamination." He said that companies, such as those involved in food packaging, should be concerned by ISO standards for air quality.
And he observed: "The BCAS and BRC code of practice is aligned with the compressed air purity levels shown in ISO 8573.1 : 2001 and although not directly stated, the purity level for air that is in direct contact with food or could come in to contact with food is equivalent to ISO 8573.1 Class 2.2.1, whilst air that will never come in contact with food, is ISO 8573.1 Class 2.4.1.
Additionally, test methods in the code refer to the test methods of the ISO standard." But he explained: "The BCAS and BRC Code of Practice recommends minimum acceptable levels of compressed air quality, which is specific to the food industry and does not require the extra expense required to meet Class 0." And White stressed: "It is important to remember, the aim of the code is to provide air quality recommendations to the food industry that will protect both the manufacturer and the consumer, not to over-specify air quality in an attempt to sell plant equipment.
Compliance may require little on the part of the manufacturer as many will find that they already comply with most or all of the code." He continued: "A full audit of the compressed air system should be conducted as part of the HACCP process and where required, equipment updated or additional purification added.
Additional filters can be installed simply and relatively inexpensively at point of use.
Costly compressors do not have to be changed in order to comply." Domnick Hunter added that it is now offering a free updated guide to the ISO 8573.1 : 2001 Compressed Air Quality Standard and a free guide to food-grade compressed air.
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