Virtually every industrial chemical process requires compressed air. It is used to texturize products, dry sterilized equipment, form containers, move ingredients through lines, and serve as protective blankets around product stored in tanks. As essential as it is, compressed air also can be a prime source of contamination.
This problem is addressed by standards for clean, dry air — chiefly the International Organization for Standardization’s ISO 8573-1, which defines contaminants and specifies a range of purity classes for particular processes. Meeting this standard requires careful treatment and filtration.
First, it’s important to identify the probable contaminants in your facility. The impurity most prevalent in compressed air systems usually isn’t rust or dirt, although equipment can shed solid particulates. The greater risk is liquid — a combination of condensate that forms as compressed air cools and lubricants that leach from oil-flooded compressors, which are the most common units at plants. Moisture itself is a threat, of course, but a water/oil mixture also is an ideal organic diet for bacteria, which multiply quickly in the warm crevices of compressed air lines.
Thus, keeping air dry and oil-free is critical to product quality and safety. This typically requires a series or “train” of filters and dryers. Although each facility is unique, appropriate treatment usually involves prefiltration in the utility room as well as point-of-use filtration before compressed air contacts a product.