In modern industrial production, screw air compressors have become indispensable core power equipment for many enterprises due to their high efficiency, stability and reliability. However, insufficient discharge volume will lead to lower production efficiency, compromised product quality, and even equipment downtime, causing significant economic losses. Identifying and solving the root causes of insufficient discharge volume is critical to ensuring production continuity and reducing operating costs. This article professionally analyzes the 7 common causes and provides detailed practical solutions to help you troubleshoot quickly and restore the compressor to optimal operation.

1. Clogged Air Filter: Blocked “Breathing Passage” Reduces Intake Efficiency

In-depth Analysis

The air filter is the first protective barrier of the compressor, blocking dust, particles and fibers from entering the unit. The filter element is usually made of high-precision filter paper or synthetic fiber. After long-term operation, impurities accumulate on the surface to form a filter cake, blocking airflow. When severely clogged, intake resistance rises sharply, resulting in insufficient intake air, weakened compression and greatly reduced discharge volume. In addition, heavy clogging increases motor load, raises energy consumption and may even cause overload  tripping.

Solutions

Regular inspection and cleaning: Inspect the filter every 500–1000 hours (or monthly). For light clogging, purge with low-pressure compressed air (<0.3 MPa) from inside to outside. Do not knock or brush vigorously to avoid damaging the filter media.

Timely replacement: Replace the element immediately if it darkens, resistance remains high after cleaning, or it reaches the service life (normally 2000 hours or 1 year). Always use genuine, high-quality elements.

Optimize installation environment: Install the compressor in a clean, ventilated area away from dust and corrosive gases. Add a pre-filter under harsh conditions.

Differential pressure indicator: For high-end compressors equipped with a differential pressure gauge, replace the filter when the alarm activates.

2. Intake Valve Failure: Restricted Opening Hinders the Compression Cycle

In-depth Analysis

The intake valve (unloading valve, butterfly valve) controls the air entering the main unit. Common failures:

Insufficient opening: Faulty control air circuit or solenoid valve prevents full opening.

Stuck valve disc: Carbon deposits, rust or foreign matter block movement.

Poor sealing: Aging or damaged seals cause air leakage.

Abnormal control pressure: Unstable or low control pressure leads to malfunction.

These failures directly reduce intake volume and discharge capacity.

Solutions

Check control system: Inspect control air lines, solenoid valves and pressure switches; ensure stable control air pressure.

Disassemble, clean and inspect: Remove carbon deposits, oil and foreign objects; check for wear on disc, seat, seals and actuators.

Replace damaged parts: Use genuine components for badly worn parts.

Adjust and calibrate: Calibrate the opening parameters per the manufacturer’s manual.

3. Minimum Pressure Valve Failure: Unstable System Pressure Affects Oil-Gas Separation

In-depth Analysis

The minimum pressure valve maintains system pressure and has three main functions:

Build internal pressure for lubrication circulation at startup.

Prevent oil-gas backflow during unloading.

Ensure effective oil-gas separation.

If the valve sticks open, the spring fails or seals leak, system pressure cannot build properly, separation efficiency drops, oil is carried over with air, and effective discharge volume decreases.

Solutions

Check the valve: Ensure smooth opening/closing and no obvious leakage.

Disassemble, clean and inspect: Check the spool, spring and seals for wear or fatigue.

Replace faulty parts: Use genuine spares for worn or damaged components.

Pressure gauge comparison: Compare readings at the compressor outlet and air receiver to verify performance.

4. Oil-Gas Separator Blockage: High Internal Resistance Reduces Volume & Efficiency

In-depth Analysis

The oil-gas separator removes lubricant mist from compressed air and recycles oil. The filter element is made of multi-layer fiberglass. After long running, impurities and oxidized oil clog the element, causing:

Reduced discharge volume

Higher energy consumption

Increased oil carry-over and consumption

Excessive pressure in the oil-gas tank (safety hazard)

Solutions

Replace on schedule: Change the separator element every 2000–4000 hours (or 1 year); shorten interval in harsh environments.

Monitor differential pressure: Replace when ΔP exceeds 0.08–0.1 MPa.

Use high-quality parts: Choose genuine or branded elements to avoid secondary contamination.

Maintain clean oil: Use qualified lubricant and change regularly.

5. Air Pipe Leakage: Invisible Energy Loss Hidden Killer

In-depth Analysis

Leaks waste compressed air and electricity. Common leakage points:

Pipe joints, flanges, valves

Hoses, fittings, pneumatic components

Air tanks, drains

Leaks force the compressor to run overloaded, resulting in insufficient airflow and higher power costs.

Solutions

Systematic leak detection: Use listening check, soapy water test or ultrasonic leak detector.

Prompt repair: Tighten joints, replace seals and damaged pipes.

Optimize piping: Reduce joints; use welding or compression fittings.

Maintain pneumatic components: Ensure good sealing of cylinders, tools and valves.

6. Excessive Air Consumption: Overload Signal – Reassess Supply & Demand

In-depth Analysis

This is not a compressor fault but actual demand exceeding total output. Causes:

New equipment or production lines

Process changes requiring more air or higher pressure

Aging equipment with abnormal consumption

Unnecessary air use or waste

When demand exceeds supply, system pressure drops and pneumatic equipment malfunctions.

Solutions

Accurately assess demand: Survey total air consumption, measure peak and average flow.

Optimize usage: Eliminate waste; optimize process pressure; use graded pressure supply.

Add compressors: Install variable-frequency compressors or upgrade to larger units.

Centralized air supply: Adopt centralized system for large factories.

7. Main Airend Failure: Fatigue Damage of Core Components Requires Professional Repair

In-depth Analysis

The air end is the core with a pair of meshing rotors. Failures directly reduce compression efficiency:

Rotor wear increases internal leakage

Bearing damage causes noise, vibration and high temperature

Shaft seal failure leads to oil leakage and dry running

Carbon deposits affect meshing accuracy

Symptoms: abnormal noise, strong vibration, high discharge temperature, high oil consumption.

Solutions

Professional diagnosis: Contact certified technicians immediately.

Overhaul or replacement: Replace bearings and seals; overhaul or replace the airend if seriously damaged.

Preventive maintenance: Use qualified lubricant, avoid overload and high-temperature operation.

Conclusion

Insufficient air volume of screw air compressors can result from single or multiple causes. With systematic troubleshooting and the solutions provided, you can quickly resolve the problem and ensure efficient, stable operation.

Remember: Prevention is better than cure.A complete daily inspection, regular maintenance program and high-quality genuine consumables are the best ways to ensure long-term reliability and avoid insufficient discharge volume.