Plant & Works Engineering
Oil alert
Published:  07 March, 2017

Mark Ranger, business line manager, oil-free air division at Atlas Copco Compressors UK, looks at how to ensure the right compressed air for the food and drink industry.

During the last five years, the food and beverage industry has witnessed several scandals that have led companies to recall their products from the market. In fact, early this year, it was reported by insurance firm Lockton that the number of food recalls by the Food Standards Agency (FSA) in 2015 grew by 78% compared with the previous year. The presence of bacteria was responsible for 15% of recalls. Of those recalls, half were due to salmonella, and 12% of the recalls were because of a foreign object or body – the most common being metal. 1

This shows that the source of contamination in the food and drink industry varies but the financial, reputational and legal implications are almost always very damaging. In seeking to reduce the risk, companies operating in food and drink production must look at many factors, including compressed air, a vital source of energy that can also be a source of contamination.

Compressed air is an almost silent, invisible form of energy used in different stages of food and drinks processing and manufacturing, for instance in food filling machines, packaging, transporting and mixing. It is considered that air in its pure state has no moisture or contaminants. However, in reality, this is not the case. To control and reduce contamination, it is recommended that companies follow a six-stage optimisation process to meet the key considerations that help ensure good air quality; as stated in the BCAS Food and Beverage Grade Compressed Air Best Practice Guideline 102 (2014).

Among the recommendations of the mentioned guide, it is critical for food and beverage manufacturers to define and know the air demand profile that they need. This can be achieved by conducting an ISO 11011 energy audit on their compressed air system and distribution network. This is a detailed and objective compressed air audit that can be carried out after the first stage of the optimisation process: A site visit by a compressed air service engineer to estimate the potential energy savings at stake and to ensure the manufacturer is using the right type of compressor. For any process where compressed air comes into direct contact with end products, for example food or beverages on a production line, the use of oil-free compressors is highly recommended. These are proven to be the only way to 100% avoid compromising product quality by dirt or compressor oil carry-over. In applications where this is not the case oil-injected compressors with filtration can be considered.

The compressed air audit should specify potential savings, based on an accurate measurement of current status using tools that quantify flow, pressure, electrical current input, ambient conditions, air quality, pressure dewpoint and leakages. Air leaks are the biggest source of energy waste in compressed air systems, with a leakage point as small as 3mm costing an estimated £3260 in wasted energy over the course of a year. In addition, this second step allows manufacturers to identify the air quality that their process requires. In the food and beverage industry, there are two considerations when it comes to compressed air. The first consideration is direct contact, defined as the process whereby compressed air is in contact as part of the production and processing including packaging and transportation of safe food production. Secondly there is indirect contact, whereby compressed air is exhausted into the local atmosphere during food preparation, production, processing, packaging or storage.

For direct contact, the Food and Beverage Grade Compressed Air Guideline recommends a Compressed Air Purity Designation ISO8573.1 (2010) class 2:2:1. This means that the amount of dust must be < 1 micron, the pressure dewpoint should be -40oC and the oil content

The third step of the optimisation process will deliver a detailed report recommending system improvements to achieve the advised air quality needed in your production. In applications where the air quality that you need is in the direct contact category, it is advised to use a 100% oil-free compressor whose technology is proven to meet the most stringent quality standards of compressed air. Also, when combined with VSD technology they offer low total cost of ownership: by avoiding filter replacements, eliminating the costs of lubricants, cutting maintenance costs and that of treating oil-laden condensate, and importantly, avoiding the costs of extra energy needed to combat filter-induced pressure drop. The identified enhancements should then be carried out under step four of the process.

Step five seeks to maintain optimised performance over the long term. With the introduction of a compressor monitoring system energy performance can be continuously measured and assessed. More importantly, monitoring your system enables you to check if the air quality is meeting the recommended levels in order to avoid the compressed air you are using on your production line becoming a source of contamination.

Finally, the sixth stage of the optimisation cycle involves repeating the original audit at regular intervals to ensure that your air quality is kept at optimal levels and that new saving opportunities can be identified and acted upon. By following these six steps in a coordinated manner, compressed air users in the food and beverage industry can implement a pattern of good practice that can ensure the purity of their compressed air and deliver calculable financial and sustainability benefits year on year.


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