The burning question is this - can one get clean air ? The short answer is yes, however, there is a also a "but". Firstly, 'clean' must be specified and then the cost must be considered. The questions normally start when people find out there's oil in compressed air. Some solutions include, get an oil free compressor. There is no such thing. You can get an oil free system, but that means adding some expensive equipment behind the compressor. There are different levels in this depending on what you specify. One can remove the liquid oil quite easily directly after the compressor, but oil vapour and aerosols are a different story.
I will try to keep this as non-technical as possible but one needs to understand enough to realise where the issues are generated and solved. This applies both to the hygiene and the engineering sides. Both sides must have enough technical knowledge on their side of the issue to be able to explain to the other side what their problem is. You must talk to each other on a pretty technical level with a huge level of practicality. If you can not do that you will not get the best solution and you may even have an expensive ‘solution’ that does not solve the issue at all.
Why use compressed air?
Low maintenance and downtime associated with pneumatics are key reasons for using compressed air. Do not be mistaken however, it is an expensive commodity. Then there is the issue that it is an excellent contaminator if not controlled properly. Quite often this handy resource is misunderstood by both the hygiene guys as well as the engineering guys.
I am not trying to explain the standards that one must use, there are manuals, consultants and even companies that will do it for you. This article simply highlights some pitfalls as well as some tips that will make your life easier, and at the same time fix the real issues.
Determine your risk
First and foremost there must be an honest and practical determination as to what the risk of contamination in your specific areas of application are. If you use the air to cool the product it is totally different from having pistons moving sealed packs. Obviously the risk of contamination and the level of ‘clean’ are totally different. Make sure you understand the real issue and address that. Air released a couple of meters away from an open pack will normally be much less of an issue than blowing air straight into the pack just before filling it.
In essence a practical HACCP study should be done for each identified contamination point or area. A broad statement will be that the most critical areas will be in the packaging area and some specific areas in manufacturing.
There are ‘clean’ air specifications available world wide, get the preferred one for your factory and work through it with a good deal of practicality. (This statement applies to both the hygienic and engineering people.) There are normally three levels of risk to the product in these specifications. The risk is different in different situations. Determine these and determine the specification for each different situation. You will most probably end up with different levels of ‘clean’ air for different areas. If you decide on a one system for all, you will end up with a very expensive solution. The cost is not only in capital but also in continuous maintenance and energy costs. Do not over specify just to be sure, it can easily become more expensive than the product can support. Obviously the boiler house will have a totally different requirement as the packing area of sensitive product. Pet food is different from baby food etc.
In Part 2 of this article we will look at compressed are contaminates - the risks and the specifications.
Author
Pieter de Waal
