Compressed Air – a hidden contamination risk

The presence of air compressor lubricant in compressed air

Lubrication is required for running a air compressor smooth and efficient. However, contact is possible between compressed air and lubricant, so that oil mist can come in the air. Replacement by oil-free compressors can be avoided by switching to food grade lubricant specially developed for compressors. As a result, it is possible, in the event of contact, to stay within the FDA standards, while the operation of the compressor can even improve.

The presence of air compressor lubricant in compressed air can be a major area of concern for food & beverage manufacturers. Commonly used in food processing plants, compressed air is used to mix liquids and provide safe power delivery for critical tasks in areas such as material transport, filling lines, spray applications and drying. However, as the majority of air compressors are oil lubricated, food safety can be quickly compromised by the use of non-food grade compressor oils.

Essential to the smooth and efficient running of air compressors, lubricating oils help to reduce metal-to-metal contact between the compressor’s rotor or helicoidal screws and the cylinder housing. This helps to minimise expensive component wear and damage, reducing unplanned downtime and enabling operators to realise the low maintenance and reliable performance benefits of compressors. As compressors operate in close proximity to food stuffs, there is a realistic threat of accidental oil contact, which is why Shell lubricants companies have developed a new food grade compressor oil.

Oil Mist Risks

Oil mist can form in compressed air as a result of high operating temperatures and can be difficult to detect. This increases the threat of the oil mist coming into direct contact with food; a problem that can easily go unnoticed until detected by the consumer. By this time though, it can be too late, as consumer health and welfare has been jeopardised. This can bring the company under public scrutiny, which can severely impact on long-term market performance and survival.

The amount of oil in compressed air depends on a number of factors, including the condition of the machine and how regularly it is maintained, the condition of the coalescer and filters and whether parts that have been fitted have been recommended by the original equipment manufacturer. Other risk factors include the age of the compressor oil, whether the correct oil is being used and whether secondary filters have been fitted. Failure to maintain and regularly replace filters will also increase the risk of contamination.

As Figure 1 shows, even when using multi-stage filtration, there is still a risk of contamination with food as oil particles remain in the compressed air. While a multi-filter system can reduce oil mist concentration to as low as 0.1 parts per million (ppm), it is impossible (under normal conditions) to remove 100 per cent of oil mist for an end result of 0.0ppm – the maximum tolerance of non-food grade lubricant contamination with food and beverages allowed by the US Food and Drug Administration (FDA).

Shell / Lubritech
Diagram of oil and air flow around compressor

Fig. 1. It’s impossible to remove 100% of oil mist

Reducing Contamination

While it is possible to avoid the presence of an oil mist by using an oil-free compressor, this is an expensive option requiring replacement of existing non-oil free compressors. A much more cost-effective solution for operators is the use of food grade compressor oils. Specifically developed for use in air compressors, high quality, synthetic, H1 approved, food grade compressor oils such as Shell Cassida ® Fluid CR 46 have been formulated using approved additives and base fluids. This composition means that Shell Cassida Fluid CR 46 is tasteless, colourless and odourless and will not contaminate food in quantities less than the US FDA’s maximum permitted level for H1 lubricants of 10 parts per million.

Fully registered by the NSF as H1 for incidental food contact, Shell Cassida Fluid CR 46 is a fully synthetic oil that can increase food safety and compressor performance. Cassida Fluid CR 46 has excellent high temperature resistance to oxidisation, which reduces gum and lacquer deposits on the coalescer, reducing filter saturation and the risk of oil mist. As well as improving air quality, the reduction in deposits enables better fluid circulation and lubrication of the compressor, improving efficiency and lowering maintenance costs.

Cassida CR 46 – Food Grade Performance
Atlas Copco oil-flooded GA 37 screw compressor, after 5,756 hours

Shell / Lubritech
Clean Coalescer

Clean Coalescer will remove oil mist efficiently

Shell / Lubritech
Oil filter mounting

Oil Filter Mounting Plate: no sign of oil oxidation

This compressor was running on a competitor fluid, which showed deposits before the oil change at 4,000 hours. It was flushed and filled with Shell Cassida Fluid CR 46. After 5,756 hours on Shell Cassida Fluid CR 46, the coalescer and oil filter were inspected with the following results:

  • Both were found clean and free from deposits
  • Seals were in excellent condition
  • Oil Analysis showed oil still in excellent condition
    (oil should be analysed periodically)

Shell Cassida CR 46 has been used in these compressors:
Atlas Copco, Berko Compressors, Compair Hydrovane, Gardner Denver, Grassair, Hitachi Compressors, Ingersoll Rand, Rietschle, Vemag Maschinenbau GmbH.

Food Grade Benefits

Although the risk of compressed air contamination is difficult to detect, the consequences are much more visible…. especially on the bottom line. Excessive costs can be incurred as whole batches of contaminated food are destroyed and unadulterated products recalled. Furthermore, production lines may have to be completely stopped as the contamination incident is rectified and compressors cleaned.

High quality, synthetic, food grade lubricants such as Shell Cassida CR 46 can help operators to maintain cleaner air and improve food safety levels, reducing the adverse impact of oil mist contamination. These safety benefits are supported further with excellent compressor oil performance, which can lead to extended oil drain intervals, meaning that operators do not have to make a choice between performance and safety.


Switch to food grade lubricants

High-performance lubricants and greases play an important role in ensuring reliable and efficient operation of production machinery. For food manufacturers, the use of machinery and components such as mixers, pumps, sterilisers, can seamers, and conveyor belts are vital to their operations.

Lubricants and greases can present a serious threat to food safety if they come into contact with foodstuffs. The risk is best minimised through a number of measures, namely good engineering design, hygienic operations and the use of food grade lubricants. This last measure, the use of food grade lubricants, is becoming increasingly common. Companies make the switch away from traditional mineral-based products to ensure maximum food safety and to protect their brands. This has been fostered by more rigorous safety regulations, and as a result, food manufacturers tend to switch over to food grade lubricants completely.

Fuchs Lubritech
Lubricants and greases can present a serious threat to food safety if they come into contact with foodstuffs.

Minimum risk

With exacting demands placed on modem day processing equipment, food producers are looking for continuous, 24/7 production. This combined with the specific lubricant needs of specialist equipment such as rotary cookers (sterilisers), can seamers and separators, means that high-performance food grade lubricants are vital to business success, ensuring maximum productiviry and minimum risk.
Over the last decade the work of the US Department of Agriculture and the Food & Drug Administration, and recently the governmental organisation NSFInternational (which has taken over food grade lubricant registration from the USDA), has been well documented and well received by the food industry.
The FDA produces a list of non-food components which are permitted in food grade lubricants. NSF verifies the formulations of these food grade lubricants and registers them as Hl. This is especially important in furthering the correct use of food grade lubricants across the industry.

Fuchs Lubritech
Bottle line


EHEDG (European Hygienic Equipment Design Group) also produces industry guidelines which focus on the use of lubricants in food and beverage manufacturing. These guidelines describe the typical contamination points, which may be LCPs (Lubricant Control Points) in a Hazard Analysis Critical Control Point system (HACCP). EHEDG also provides many recommendations covering the production and use of food grade oils and greases.
Whilst improving engineering design at Critical Control Points (CCPs) can reduce the likelihood of contamination, it is not always possible to eliminate these risks. Therefore incidental contact of lubricants with food products is an ever-present threat. By regularly monitoring lubricant control points and using Hl food-grade lubricants, companies can effectively reduce the risk or contamination, without compromising food quality and protecting both the consumer and the brand."

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Featured expert: Pieter Van de Schepop

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  • Food-grade lubrication
  • Compressed air