Compressed air picks up impurities from two main sources: the ambient environment and the compression process itself. The most common contaminants include:

Solid particles
Dust, dirt, rust, and pipe scale can enter the system through air intakes or corroded lines.

Water (vapour, liquid, and aerosols)
Moisture is introduced through ambient humidity and condenses as the air cools. Water accelerates corrosion, damages tools, and creates a breeding ground for bacteria.

Oil (aerosols and vapour)
Oil-lubricated compressors introduce tiny oil droplets and vapour into the air stream, which can contaminate sensitive equipment or products.

Microorganisms
Bacteria and spores drawn in from the surrounding air can survive and multiply in wet or poorly filtered systems.

Chemical vapours
Contaminants like sulphur dioxide, hydrocarbons, or vehicle exhaust can enter via air intakes—especially in industrial or urban settings.

Without proper filtration, these contaminants can cause a variety of operational and quality issues, including:

• Blocked valves, nozzles, and actuators
• Wear and tear on tools and machinery
• Product contamination (especially in food, pharma, or electronics)
• Unhealthy or unsafe working conditions
• Failure to meet industry standards like ISO 8573-1

Even oil-free compressors require filtration—because ambient air and downstream piping still introduce particles, water vapour, and microbial contaminants.

Contaminants can enter or form in several areas of a compressed air system:

• At the intake – Environmental pollutants like dust, pollen, exhaust, and moisture
• Inside the compressor – Oil aerosols, wear particles, and heat-induced vapours
• In the piping network – Rust, bacteria, and residual condensate
• From air treatment equipment – If filters or dryers are poorly maintained

That’s why filtration is needed at multiple stages—not just at the compressor outlet.

Your filtration needs depend on your application, compressor type, and air quality standards. For example:

• General industrial use may only require coalescing and particulate filters.
• Food & beverage applications need sterile or activated carbon filters to meet purity classes.
• Electronics manufacturing demands ultra-dry, oil-free air, with multi-stage filtration and precise monitoring.

It’s also essential to size your filters correctly and service them regularly to avoid pressure drop or efficiency loss.