The burning question being, can one get clean air ? The short answer is yes. But there is a but, first ‘clean’ must be specified and then the cost must be considered. Part 2 of this article looks at contaminants and offers some technical tips
The main culprits are moisture, solid particles, oil aerosols & vapours. Each has its own removal method and specification level. Be sure to address all if they are unacceptable to your product.
Compressed air must be purified of contaminants before being used in hygienically sensitive areas. The contaminants are water vapour and moisture, solid particulates (including spores) and oil aerosols and vapours. Some are controlled at the compressor itself and some can only be done effectively just before the point of use.
The technical side of the task team must do some research as to where and how the contaminants can be generated in your specific layout of air supply. This will determine the best way and place to do the cleaning processes. Some contaminants are generated in the supply pipes to the different areas. (Rust and bacteria)
The presence of moisture is the primary concern for the food industry because moisture creates the ideal habitat for micro organisms and fungus. Moisture may reside in the piping system near the point-of-use where compressed air comes into contact with food products. Micro organisms and fungus can grow inside the piping system and then be blown onto food products or food containers.
Oil aerosols and vapours is a significant concern. One myth in compressed air systems is that the use of an oil-free air compressor frees the system of any compressed air treatment requirements. This is not the case. Ambient air ingested by air compressors will carry water vapour, particulates, and hydrocarbons and compressed air dryers and filters are always therefore required.
|
Max no of particles / m3 |
Humidity (Water vapour) |
Total Oil (Aerosol + vapour) |
ISO8573.1 |
||
Risk type |
0,1 - 0,5 micron |
0,5 - 1 micron |
1 - 5 micron |
|||
Direct contact |
100 000 |
1 000 |
10 |
-40°C PDP |
0,01 mg/m3 |
Class 2.2.1 |
Non contact - Low risk |
100 000 |
1 000 |
10 |
+ 3°C PDP |
0,01 mg/m3 |
Class 2.4.1 |
One of the most overlooked issues is the bad habit of ‘cleaning’ with compressed air. Compressed air cannot clean an area, it simply moves dust and other particles from one area to another. This should be prohibited and not just in sensitive areas. It is also unsafe as it can blow solids into eyes and ears, it is normally a noise creator of note and makes fine particles airborne that is bad for your lungs.
Author
Pieter de Waal
By Guest Author on 25 April 2017
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 a...