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Keeping oil out of food production

22 March 2021

Oil contamination is a potential risk when using compressed air in the food industry, but proper removal techniques – and choosing the right compressed air solution – can help to safeguard consumer health, explains Mark Whitmore. 

Compressors have found their way into almost every aspect of manufacturing and the food industry is no exception. Here, compressors are used widely – from packaging machinery to specific food processing tasks such as filling. However, like few other industries, the food sector is subject to very strict hygiene requirements. For the food industry, this is ISO8573-1 – which measures compressed air to ‘oil-free class 0’.

What is perfectly normal in, say, car production is unacceptable in food processing. Contamination can cause line shutdowns, wasted production runs and – if not spotted early enough – product recalls. To maintain efficiency – and avoid penalties – food production sites need to avoid these issues.

Air contamination
Compressed air used in the food industry must adhere to high standards. However, there are several ways in which it can become contaminated – posing a potential risk to food production. One contamination source is atmospheric air, which contains water vapour, dirt particles, oil vapour and micro-organisms. These will become far more concentrated when drawn into a compressor, so must be removed – or reduced – to ensure compressed air quality.

The penalties for food contamination can be severe. The best-case scenario is to spot the problem early, which may mean shutting down a line and solving the problem before resuming production. In the worst case, contaminated food is shipped out for sale – and later subjected to a product recall. This scenario can lead to hefty fines – and a loss of reputation – for the producer. Oil contamination is a particular problem for the food industry. Many compressors rely on mineral oil in some way – such as for lubrication. This oil can find its way into the compressed air stream – from where it could contaminate packaging or even the food itself. Because compressors are a vital part of food production, it is not practical to get rid of them. Instead, food processors need to understand how compressors cause contamination, and work to prevent it happening.

Fixing the problem
One way to reduce the risk of oil contamination is to use an oil-free compressor. As the name implies, this uses no machine oil at all – which cuts off one source of contamination. However, like conventional compressors, oil will still be drawn into the compressor from the atmosphere. For this reason, the best first line of defence is to ensure that oil from the atmosphere is scrubbed clean.

There are various methods to do this and will differ depending on whether the oil is in liquid, aerosol or gaseous form. Liquid oil is removed by opening a drain valve within the system. This discharges an oil-water mixture called a condensate, which must then be disposed of properly. Oil aerosols can be removed using coalescing filters. These encourage the aerosols to combine into liquid oil drops that can be drained off. Oil vapour can be removed with a carbon filter containing activated charcoal.

An alternative approach is to use an oil converter – ssuch as BOGE’s bluekat converter - which deals with all forms of oil contamination. Here, air is drawn into the compressor and pre-heated to 200°C and then flows into a converter – where a catalytic material oxidises any hydrocarbons (including oil) into carbon dioxide and water.

Oil-free savings
Oil-free compressors are more expensive than conventional models but can offer total cost of ownership (TCO) benefits – working out more economical in the long run.

This is because elements such as ongoing energy costs, machine maintenance and oil management can be reduced using an advanced oil-free compressor. For instance, an energy management system provides an ongoing picture of how efficiently a compressor is working – and could cut energy costs by 30% or more. In addition, a heat recovery system recoups much of the energy that is wasted when compressing air. Because energy accounts for around 75% of TCO, these measures can make a big dent in ongoing expenses.

Oil-free compressors also reduce the need for oil management. Oil changes, filters, removal and storage all increase costs – but an oil-free screw or piston compressor removes these from the equation. Oil leaks – another expensive maintenance problem – are also banished.

There are other cost advantages of choosing oil-free air compressors or choosing a converter to deliver 100% oil-free air. However, the most important could be this: reducing the risk of shutting down production – or making a product recall.

Mark Whitmore is general manager at BOGE Compressors.


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