Factors Causing Excessive Oil Consumption in Air Oil Separators

Failure Factor

Specific Issues

Cause Analysis

Solutions

Oil Return System

1-1 Damage to oil return check valve (filter blockage, insufficient oil return)

A damaged check valve (allowing bidirectional flow) causes oil to flow back into the separator after shutdown. During subsequent operation, oil fails to return to the main unit promptly and escapes with air.

Dismantle and inspect the check valve; clean debris or replace with a new one if damaged.

1-2 Improper installation of oil return pipe

The oil return pipe is not inserted close enough to the separator bottom (optimal distance: 1-2mm from the arc center), preventing timely oil return and causing oil accumulation to escape with air.

After depressurizing, adjust the pipe to 1-2mm from the separator bottom; ensure size compatibility with new separators.

1-3 Flat-mouth oil return pipe blocking the oil return port

The pipe is inserted into the separator’s lower end cap, blocking oil return and forcing accumulated oil to escape with compressed air.

After depressurizing, adjust the pipe to 1-2mm from the separator bottom.

1-4 Blockage in oil return pipeline

Foreign objects block the pipeline (including check valves and filters), preventing oil from returning. Agitated oil droplets are carried away by airflow.

After depressurizing, disassemble pipes, remove blockages, and clean the separator lid and bottom for residual particles during reinstallation.

Primary Separation System

2-1(Inappropriate oil separator barrel size)

Downsized barrels (e.g., using 10m³ barrels for 15m³ machines) reduce separation efficiency, shortening service life over time.

Design barrels matching the machine’s flow rate.

2-2 Overload low-pressure operation due to high air demand

Operating below rated pressure (e.g., 5kg/cm² instead of 8kg/cm²) increases oil mist concentration and flow velocity, overloading the separator.

Consult the manufacturer for a separator compatible with low-pressure operation.

2-3 Frequency reduction in variable frequency machines

Reduced motor speed decreases gas output while oil flow remains unchanged, impairing separation.

Use wound-type separators for low-frequency operation.

Lubricating Oil

3-1 Excessive oil filling

Overfilling exceeds the normal oil level, reducing primary and secondary separation efficiency.

After depressurizing, drain oil to the normal level via the oil drain valve.

3-2 Use of (unqualified oil) or expired oil

Poor-quality oil breaks down at high temperatures (110-120℃), forming micro-droplets (≤0.01μm) that bypass the separator.

Resolve overheating issues and use high-quality oil.

Operating Conditions

4-1 Severe operating environment

Contaminated environments accelerate oil degradation and clog glass fibers, shortening separator life.

Assess the environment, define air filter service life, and clean the machine regularly.

4-2 Low machine operating temperature

Temperatures below 80℃ cause condensation, damaging oil and glass fiber structures, leading to premature failure.

Adjust operating temperature to above 85℃ and drain condensate from the air tank daily.

Other Factors

5-1 Poor quality of oil-gas separator

Issues like incorrect glass fiber precision, poor end cap adhesion, or damaged filter layers impair separation.

Replace with a new separator.

5-2 Pressure differential sensor leakage

Unseparated oil-gas mixture bypasses the system, causing oil loss.

Repair or replace the pressure differential sensor.

5-3 Minimum pressure valve failure

Leaks or premature opening (3.5-5.5kgf/cm²) prolong pressure buildup, increasing oil mist concentration and flow velocity.

Inspect the valve; replace if necessary.

5-4 Cooler perforation

In water-cooled machines, high oil pressure (vs. 2-3KG water pressure) forces oil through perforations into the cooling system, causing loss.

Repair the cooler.