Working Principle of Oil-Air Separator

Oil-air separation generally consists of primary separation inside the oil-air tank and secondary separation by the oil-air separator element.

The oil-air mixture containing oil droplets of various sizes flows out from the air end exhaust port and enters the oil-air tank. Most oil in the mixture falls to the tank bottom under centrifugal force and gravity. 

The compressed air carrying oil mist (suspended oil particles below 1 μm) must pass through the micron-grade glass fiber filter media of the oil-air separator element for secondary separation.

Through diffusion, direct interception, inertial impaction and coalescence mechanisms of filter media, suspended oil particles in compressed air rapidly coalesce into large oil droplets. Under gravity, 

oil accumulates at the bottom of the separator element and flows back to the main unit lubrication system via the inlet of the secondary oil return pipe at the bottom recess. 

In this way, cleaner, low-oil compressed air is discharged from the air compressor.

Replacement Criteria for Oil-Air Separator Element
1. Service Life
Replace the element once the actual operating time reaches the designed service life. The service life of an oil-air separator element is normally 4,000–8,000 hours; replacement is mandatory upon expiry.
2. Equipment Alarm
Replace the element immediately if the clogging alarm is triggered within the designed service life. The typical set value for the oil-air separator clogging alarm is 0.8–1.0 bar.
Hazards of Overdue Service of Oil-Air Separator Element
1. Poor Separation Efficiency
Low separation efficiency leads to high unit oil consumption and increased oil content in compressed air. This impairs the operation of downstream purification equipment and causes malfunction of air-consuming equipment.
2. Higher Operating Cost

Solid particles in compressed air get trapped inside the filter layer of the separator element, continuously increasing the differential pressure (resistance) across the element. 

This raises unit energy consumption and increases power costs for compressor operation.

3. Shortened Service Life of Related Components
When the element fails, stripped glass fiber filter material falls into the lubricating oil. This shortens the service life of the oil filter element and causes abnormal wear of the air end.