Air straight from a compressor contains a mix of contaminants: oil, water vapour, and solid particles. If these impurities make their way into your process—through a nozzle, valve, or conveyor—it could impact product quality, shelf life, or even consumer safety. In many applications, compressed air is classified as a Critical Control Point under HACCP or ISO 22000, meaning it must be monitored and controlled just like any food ingredient.

Compressed air can interact with food in several ways:

• Direct contact – The air directly touches the food or ingredients (e.g. drying, sparging, or air knives).
• Indirect contact – The air contacts surfaces that touch the food (e.g. conveyors, filling equipment).
• Non-contact – The air is used in a utility role (e.g. valve actuation), but contaminants can still enter the system if there's backflow or leakage.

Each type of contact requires different levels of air purity, which is why understanding the risk is key to designing the right air treatment solution.

Most food manufacturers follow ISO 8573-1:2010, which defines air purity classes for three types of contaminants:

• Particles
• Water (vapour and liquid)
• Oil (aerosols and vapour)

The required class depends on your application’s risk level. For example, air used in direct contact with food might require Class 1 for oil, Class 2 for particles, and Class 2 for moisture.

Food producers may also need to comply with:

• HACCP/GFSI requirements
• FDA or EU food contact guidelines
• Retailer-specific standards

Filters
Install high-efficiency coalescing and particulate filters to remove oil aerosols, dust, and solid contaminants. Always place filters as close to the point of use as possible.

Dryers
Use a refrigerant or desiccant dryer to reduce water vapour in your compressed air system. Dry air helps prevent bacterial growth, corrosion, and ice formation.

Oil-free compressors or after-treatment
If you use oil-lubricated compressors, downstream filtration is critical. Alternatively, oil-free compressors reduce the risk at the source.

Dew point and air quality monitoring
Continuously measure dew point and air quality to ensure your system remains in spec. Many food manufacturers monitor dew point at multiple points in the line.