The demands imposed by the recently released ISO 8573 compressed air specification for food grade compressed air can prove difficult for any food or pharmaceutical company that has compressed air in direct contact with food. Even pneumatic systems that are not in direct contact with the food, but drive the pneumatic equipment that is utilised in the production process, are qualified in the specifications. Artic Driers offers some solutions.
Sources of contamination
Contaminants originate from three areas: the ambient air, wear and tear from the mechanical compression process, and inbuilt contamination within the piping and receivers. They can take the form of water vapour, liquid oil, oil vapour or solid particles.
Water will spoil food products, cause pneumatic machinery failure and allow bacterial growth in the compressed air system. Hydrocarbon vapours will condense in a piping system forming a liquid contaminant. Solid particles plug control valve orifices in pneumatic control circuits and score air cylinder walls, causing leaks. They may restrict flow through air jet nozzles used to clean food preparation surfaces or adversely affect the consistency of spray coatings applied on food products.
Treatment options
For treating compressed air which comes into contact with food products either lubricated compressors or oil free compressors can be used. The relative advantages and disadvantages of these two types of compressors are described.
There are many chemical adsorption air dryers on the market. When considering a main plant dryer with a capacity greater than 18 m³/min, serious consideration should be given to a heated type chemical air dryer with long cycle times fitted with a dewpoint controller to further extend bed drying times and reduce the wear and tear on the dryer’s components. This style of dryer will recoup its purchase cost very quickly.
If the volume of compressed air in direct contact is a low percentage of the total air required by the plant, the size of the air treatment packs can be reduced and they can be installed close to the point of use. This will greatly reduce the initial cost of purchase and later operational costs when compared with a centralised system.
The paper also gives Artic’s recommendations for treating compressed air which is not in direct contact with food.
An alternative oil removal system is the EcoTec catalytic converter system where the oil and the other hydrocarbon compounds contained in the compressed air are cracked in several stages using a physical-chemical process and oxidised. The end products are pure water and limited quantities of CO2.
The challenges for the food industry in meeting ISO 8573 are numerous and it is important to choose an air treatment supply partner carefully. This partner will need multiple skills and a broad based knowledge of dryers, inline filtration, waste water management systems and inline compressed air instrumentation. This should be backed up with a strong after sales service capability with a broad based supply chain and a long-term commitment to the compressed air treatment industry.
To read the full, detailed version of this white paper visit http://motioncontrol.co.za/+artic
For more information contact Allen Cockfield, Artic Driers International, +27 (0)11 425 3484, [email protected], www.articdriers.co.za
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