Atlas examines benefits of oil-free compressed air

Atlas Copco discussed Class 0 and oil-free air in a seminar delivered at Process Engineering Live last week.

Anil Hingorani, project manager in the Atlas Copco Compressor oil-free air division, presented an overview of oil-free applications within the process industries and discussed why air purity is of vital importance to their operations.

Hingorani's presentation covered the evolution of air purity standards, examining crucial differences between the second and first edition of ISO 8573-1.

It also covered the associated TUV test results and how they have been interpreted.

The presentation included an examination of some of the myths surrounding oil-free compression techniques and a question and answer session.

Atlas Copco Compressors offers oil-free and oil-injected compressors.

Compressor oil accounts for the majority of contamination in oil-injected compressor systems.

Relying solely on filters and dryers to remove oil leads to contamination risks.

There are three key failure risks associated with oil-injected compressor systems: that temperature rise will increase oil carry-over through the filters; that higher temperatures will severely reduce the lifetime of activated carbon filters; and that if filters become blocked because they are not changed in a timely manner, the filter will be bypassed and oil will enter the process.

The dominant factor influencing the purity of filtration systems is ambient temperature.

Oil carryover through filter media increases exponentially according to the temperature at the filtration interface.

Filter performance is often specified at 20C.

If the ambient temperature in the compressor room increases to 30C, the compressor outlet temperature could easily be ten degrees greater than that, increasing the oil carryover by a factor of 20-times the specified value.

A combination of oil-removal systems - oil separator, oil removal filters and refrigeration dryer - are the stages responsible for meeting the air quality specifications.

A failure of any one of these elements would result in contamination of the outlet air and the operator's process.

A copy of Hingorani's presentation is available on request.

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