Known as the Fourth Utility, compressed air has an endless array of industrial applications. It can power rotary equipment, drive reciprocating equipment, operate controls and impact, convey, hoist, clean, vaporize, atomise, spray, sand-blast, agitate and cool.
Because compressed air doesn’t interfere with electrical equipment, it is often used in hospital operating theatres. Because it can be used in extreme temperatures, compressed air tools are frequently employed in the maintenance of both furnaces and freezers. And because it makes processing faster and more efficient, compressed air is widely used in the food and beverage industry.
Uses in food and beverage
Compressed air has a wide range of uses in food and beverage processing, including;
● Air cleaning of containers prior to product filling
● Automated product sorting
● Blow-moulding to create food packaging containers
● Blowing crumbs off bread in commercial bakeries
● Washing down packaging machines to maintain sanitary conditions
● Conveying food and ingredients in process lines
● Filling products such as cakes and pies
● Operating diaphragm pumps to move liquid products
● Producing nitrogen used for packaging
● Cooling and freezing products
● Vacuum sealing products
● Cutting and peeling products such as fruit and onions.
Compressed air can be used in a huge variety of applications and at a range of different pressures, from up to 750 psi for blow-moulding down to 15 psi for blow-off applications. This is why it has become crucial in the various day-to-day operations of the food industry.
Problems with contamination
Contamination is a primary concern in the food and beverage processing industry. The presence of moisture can lead to the growth of microorganisms, which if not removed, can be spread through food handling machinery and ultimately to the food itself.
As well as microorganisms, other forms of contamination can include oil aerosols and vapours and also solid particulates such as dust, dirt and fungus spores. Compressed air can contribute to the spread of these contaminants, which is why the UK Code of Practice for Food-Grade Air classifies compressed air systems as three specific types in order to regulate their use in the UK food industry;
● Contact systems
● Non-Contact High-Risk systems and
● Non-Contact Low-Risk systems.
These are systems where compressed air comes into direct contact with food products (i.e. air knives). In such systems, the manufacturer must take steps to purify the compressed air to the level required by the Code to ensure no microorganisms can grow.
This can be achieved by using desiccant (adsorption) compressed air dryers in the compressor room and maintaining a -40 F (-40 C) pressure dewpoint (temperature at which condensation occurs). However, while dryers are permissible for use under British Standards, using an oil-free air compressor is a much better method for ensuring safety. With an oil-free air compressor, if there are any handling errors, there is no opportunity for oil to be spilled and present a hazard to workers, as well as damaging product and equipment. Coalescing and activated carbon filters would also be needed to remove solid particulates and oil aerosols and vapours.
Non-contact high-risk systems
These are systems where compressed air is exhausted into the local atmosphere of the food handling area. A typical high-risk example would be where compressed air is being used to blow mould into containers where food is later to be introduced. There is a high risk that moisture, oil and particulates could be present on the packaging, so the UK Code requires the manufacturer to implement the same purification measures as those required for Contact systems.
Non-contact low-risk systems
These are systems which have no contact with food products or food-packaging machinery. In such instances, the UK Code specifies a +37 F (+3 C) pressure dew point, which can be achieved with refrigerated compressed air dryers housed in the compressor room. However again, oil-free air compressors are the much safer option, dramatically decreasing the risk of particle contamination and mould growth.
While Australian food manufacturers are not bound by the regulations of the UK Code of Practice for Food-Grade Air, they do recognise them in principle, along with the International Organisation for Standardisation (ISO) and the compressed air quality standard ISO 8573, developed in 1992. This standard provides plant engineers and equipment suppliers with an internationally accepted unit of measure and clearly defines the permissible levels of contaminants in the output of an air compressor.
Only oil-free compressors can guarantee total air purity in food and beverage processing. An oil-free compressor eliminates the risk of oil vapour and residue from reaching food products, while further purification is achieved with desiccant air dryers and particulate and coalescing compressor filters.
A pioneer in oil-free compressor technology, Atlas Copco has set the standard for contamination-free compressed air in the food and beverage industry. The first compressor manufacturer to achieve ISO 8573-1 (2010) Class 0 clean air (the most stringent classification), Atlas Copco compressors ensure that the compressed air in food production processes is always below -40°C and free from any oils that could compromise food quality.
Compressed air plays a crucial role in the food industry, and manufacturers need to protect their hard won reputations by adhering to guidelines such as those outlined in the UK Code, and by using the latest technology, such as certified Class 0 oil-free compressors. These ensure their food processing systems remain contaminant-free at all times.