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Compressed Air Quality in Packaging

Article index
 The Risks Of Oil Contamination
 A Cost-Effective Solution
 Making The Switch
 Bottom Line Benefits
Non-Food Grade: A Compromise For Compressed Air Quality in Packaging

The demand for space-saving packaging has placed an added emphasis on the role of air compressors during food packaging. No longer used purely to provide pneumatic power, air compressors are more commonly used within the food zone. Although this provides operators with a cost effective packaging solution, it can increase the risk of food contamination, as the majority of compressors found in food plants are oil lubricated.

Compressor oils are essential in the smooth and efficient running of air compressors, helping 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. High quality compressor oils can meet the exacting demands of long-term continuous operation, enabling operators to realise the low maintenance and reliable performance benefits of compressors.

However, although compressor oils play a pivotal role in determining high levels of consistent performance, non-food grade oils can pose a hazardous risk to food quality and safety, which is why Shell lubricants companies have developed a new food grade compressor oil.

The Risks Of Oil Contamination

High operating temperatures can lead to oil oxidisation, resulting in excess oil being sprayed into the compressor’s rotors or screws, contaminating the compressed air. As a result, oil mist can form in the compressed air being blown into food packets or sachets, increasing the risk of direct oil contact with food, putting consumer health and welfare at risk. This can have a detrimental impact on brand reputation and consumer confidence, jeopardising company performance in a market governed by high levels of food safety.

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).

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

The amount of oil in compressed air depends on a number of factors. These factors include 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.

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 Cost-Effective Solution

Operators can significantly reduce the risks of oil contamination through the use of high performance, synthetic, H1 approved, food grade compressor oils as opposed to non-food grade alternatives. Specifically developed for use in compressors, 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 ten 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

Clean Coalescer will remove oil mist efficiently 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 4000 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

Making The Switch

To fully maximise the food safety and operational performance benefits of food grade compressor fluids, compressors should be completely drained and cleaned before being filled with food grade oils. An experienced lubricants provider such as Shell Lubricants will be able to assist operators with this and conduct an oil drain, filter change and system flush. This approach ensures that the risk of oil cross contamination is reduced, a common cause of foaming. The coalescer filter is unable to separate the foam from the compressed air, leading to an increased risk of food contact. In some cases, excessive foaming can cause the oil reservoir floats to sink, which stops the oil top-up. This can lead to insufficient lubrication and accelerated component wear as well as unscheduled stoppages.

Operators looking to make the switch from non-food grade to food grade compressor oils should also consider that not all H1 oils are synthetic and that not all oils are specifically designed for rotary or screw compressors. Oils such as these can not offer the same levels of food safety and operational performance as a synthetic compressor oil, and may negate the benefits of switching from a non-food grade oil.

Bottom Line Benefits

The fact that compressor oil mist is difficult to detect, coupled with packaging taking place at the end of the production line, can mean that food contamination can easily go unnoticed. By the time the problem is identified, it can often be too late for the operator. Whole batches of food and packaging may have to be destroyed and products may have to be recalled. High quality, synthetic food grade compressor oils can help food manufacturers and packagers to reduce this risk and protect their product, process and brand against the immeasurable damage of contamination.

For more information: FUCHS LUBRITECH GmbH

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