Find both the cause and the right treatment
On an oil-injected compressor, check separation, the oil return path, lubricant fill and cooling. Temperatures and intervals depend on the particular machine and lubricant; one oil temperature or a general evaporation multiplier as temperature rises cannot be prescribed for all machines. Arbitrarily changing the oil type is no substitute for fixing a fault.
Aerosol is not vapour
Coalescing filtration captures droplets. For vapour suitable adsorption or catalytic treatment is needed. Activated carbon has limited capacity and requires the specified pretreatment. Even an oil-free compressor does not remove everything drawn in from the surroundings or left in the pipework.
What to check in practice
- Define a total oil limit, not just a vague “oil-free” requirement.
- Assess compressor condition and the quality of intake air and pipework.
- Verify the result with measurements covering the required forms of oil.
Example scenario
A vapour measurement shows 0.004 mg/m³. If aerosol and liquid oil have not been assessed, that single figure cannot confirm class 1 for total oil. Very low vapour levels can still be accompanied by droplet contamination.
What to watch out for
- Treating an ordinary fine filter as a solution for oil vapour.
- Specifying a vague “class below 1” for an industry.
- Forgetting previously contaminated pipework after replacing the compressor.
How can I tell if activated carbon is saturated?
Pressure drop alone does not show this reliably. Operating capacity, conditions, the specified replacement schedule and appropriate measurements downstream of the adsorber are decisive. Waiting until oil is visible on the product is too late.