Screw air compressor exhaust volume is insufficient? 7 major reasons and solutions

In modern industrial production, screw air compressors, with their high efficiency, stability, and reliability, have become indispensable core power equipment for many companies. However, when an air compressor experiences insufficient exhaust volume, it can lead to reduced production efficiency and compromised product quality, or even equipment downtime, resulting in significant financial losses for the company. Understanding and resolving the root causes of insufficient exhaust volume in screw air compressors is crucial to ensuring production continuity and reducing operating costs. This article will provide a professional and in-depth analysis of the seven common causes of insufficient exhaust volume in screw air compressors and provide detailed, practical solutions to help you quickly troubleshoot and restore your compressor to optimal operating condition.

1.Clogged air filter: This obstruction in the air compressor’s “breathing passage” affects air intake efficiency.

In-depth Analysis: The air filter is the air compressor’s primary protective barrier, responsible for preventing dust, particulate matter, fibers, and other impurities from entering the air conditioner. Its filter element is typically made of high-precision filter paper or synthetic fiber. Over time, these impurities gradually accumulate on the filter element’s surface, forming a filter cake that obstructs air flow. When blockage reaches a certain level, intake resistance increases dramatically, causing the compressor to draw in air far below its designed value. This directly weakens compression capacity and significantly reduces exhaust volume. Furthermore, severe blockage increases the load on the compressor motor, leading to increased energy consumption and even motor overload tripping.

Solution:

Regular Inspection and Cleaning: It is recommended to inspect the air filter element every 500-1000 hours (or monthly). For minor blockages, use low-pressure compressed air (less than 0.3 MPa) to purge from the inside out. However, avoid forceful knocking or brushing to avoid damaging the filter media.

Timely Replacement: Filter elements must be replaced immediately if their color darkens, if resistance remains high after purge, or if they reach the end of their service life (typically 2000 hours or one year). Always use filter elements that meet manufacturer specifications and are reliable in quality. Inferior filter elements not only provide poor filtration but can also break, allowing impurities to enter the main unit. Optimize the environment: Install the air compressor in a clean, well-ventilated environment away from dust and chemically corrosive gases. For special operating conditions, consider installing a pre-filter to extend the life of the main filter element.

Differential pressure indicator: Some high-end air compressors are equipped with an air filter differential pressure indicator, which sounds an alarm when the differential pressure exceeds a set value, prompting replacement.

Screw air compressor

2.Intake valve failure: The air compressor’s “lung valve” is restricted from opening, restricting the compression cycle.

In-depth analysis: The intake valve (also known as an unloading valve or butterfly valve) is a key actuator for controlling air intake in the air compressor. It controls the air flow entering the main unit by adjusting the opening of the valve disc. Common failures include:

Insufficient opening: A fault in the control air circuit or solenoid valve prevents the intake valve from fully opening.

Stuck valve disc: Carbon deposits, rust, or foreign matter inside the valve body prevent the valve disc from moving smoothly, preventing it from opening or closing properly. Poor sealing: The seal between the valve disc and valve seat may be aged, damaged, or contain foreign matter, leading to small amounts of air leakage and affecting compression efficiency.

Abnormal control air pressure: The intake valve is typically controlled by the air supply pressure. If the control air pressure is unstable or too low, the intake valve may malfunction.

These faults will directly reduce the amount of air entering the main unit, resulting in a decrease in exhaust volume.

Solution:

Check the control system: Check the control air line, solenoid valve, and pressure switch of the intake valve for proper operation. Ensure that the control air supply pressure is stable and meets requirements.

Disassembly, cleaning, and inspection: Regularly disassemble and clean the intake valve to remove internal carbon deposits, oil, and foreign matter. Inspect the valve disc, valve seat, seals, and actuator for wear or damage.

Replace damaged parts: If the valve disc, valve seat, seal, or actuator cylinder is severely worn, replace them with genuine parts immediately.

Adjustment and calibration: For intake valves with adjustment mechanisms, perform the correct opening adjustment and calibration according to the manufacturer’s instructions.

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

In-Depth Analysis: The minimum pressure valve, located after the oil-gas separator, is a critical component for maintaining internal pressure in the air compressor system. It has three main functions:

Establishing Internal Pressure: During the initial startup of the compressor, it limits the discharge of compressed air and quickly builds up system pressure, facilitating lubricant injection and circulation.

Preventing Oil-Gas Backflow During Unloaded Operation: During unloaded operation, it maintains a certain pressure to prevent oil and gas from flowing back into the air intake.

Ensuring Oil-Gas Separation Effectiveness: It maintains the required operating pressure within the oil-gas separator to ensure the proper separation efficiency of the oil-gas separation element.

If the minimum pressure valve is stuck in the open position, the spring fails due to fatigue, or the seal is leaking, system pressure will build slowly or fail to reach the set value, impairing oil-gas separation effectiveness and allowing large amounts of lubricant to be discharged with the air. This will also affect the effective output of compressed air, manifesting as insufficient airflow.

Solution:

Checking the Valve: Observe whether the minimum pressure valve opens and closes smoothly and whether there are any obvious leaks on the valve body. Disassembly, Inspection, and Cleaning: Regularly disassemble and inspect the minimum pressure valve, clean the interior, and check the valve core, spring, and seals for wear, fatigue, or damage.

Replace Faulty Parts: If the spring is fatigued, the valve core is worn, or the seal is damaged, replace them promptly. We recommend using genuine parts to ensure performance and life.

Pressure Gauge Comparison: Observe the compressor outlet pressure gauge and the air receiver pressure gauge to determine whether the minimum pressure valve is functioning properly.

4.Oil-gas separator blockage: Increased internal resistance, obstructed airflow, and reduced exhaust volume and energy efficiency.

In-depth Analysis: The oil-gas separator is a crucial component of a screw air compressor. Its core function is to separate atomized lubricating oil from the compressed air, ensuring clean output compressed air and recovering the lubricating oil for recycling. The oil-gas separator filter element is typically made of multiple layers of fine glass fiber. Over extended operation, impurities, oil oxidation products, and tiny wear particles from the oil-gas mixture gradually deposit inside the filter element, causing clogging.

When the oil-gas separator filter element becomes clogged, the resistance to compressed air passing through it increases significantly, directly leading to:

Reduced exhaust volume: Obstructed airflow reduces the actual exhaust volume output of the air compressor.

Increased energy consumption: To overcome the increased resistance, the air compressor motor consumes more power, resulting in reduced energy efficiency.

Lubricating oil loss: Excessive pressure differentials may force some lubricating oil through the filter element and be discharged with the compressed air, increasing oil consumption. Increased pressure in the oil separator tank: Severe blockage may cause abnormally high pressure inside the oil separator tank, posing a safety hazard.

Solution:

Strictly replace on schedule: Follow the manufacturer’s recommendations, typically replacing the oil-gas separator filter element every 2,000-4,000 hours (or one year). In harsh environments or high operating loads, the replacement interval should be shortened.

Pay attention to differential pressure: Most air compressors are equipped with an oil separator differential pressure gauge. When the differential pressure exceeds 0.08-0.1 MPa, consider replacing the oil separator filter element.

Select high-quality accessories: Purchase high-quality oil-gas separator filter elements from genuine manufacturers or reputable brands. Inferior filter elements not only have poor separation performance and a short lifespan, but may also cause secondary contamination to the system.

Keep the oil clean: Regularly replace the air compressor lubricant and use qualified oil to reduce oil oxidation and impurity formation.

5.Pipe Leaks: Invisible “Energy Loss,” the Hidden Killer of System Efficiency

In-Depth Analysis: Leaks in compressed air systems are a common energy waste in industrial production. They not only lead to insufficient airflow but, more seriously, cause significant electrical energy losses. Leaks may occur in:

Pipeline Joints: Poor seals at threaded and flanged connections.

Valves: Worn or faulty internal seals in ball valves, globe valves, solenoid valves, etc.

Hoses and Fittings: Cracked hoses due to aging, and loose fittings.

Pneumatic Components: Poor seals in cylinders, air motors, filters, pressure reducing valves, etc.

Air Tanks: Microscopic cracks in welds, drain valves, etc.

These leaks are like “small holes,” wasting precious compressed air into the atmosphere. This forces the air compressor to operate at an increased load to maintain system pressure, ultimately resulting in insufficient airflow and increased electricity costs.

Solution:

Systematic Leak Detection: Establish a regular pipeline leak detection system using the following methods:

Auditory Method: In a quiet environment, listen carefully for any “hissing” sound of air leaks.

Soapy Water Method: Apply soapy water to the suspected leak site and observe for bubbles.

Ultrasonic Leak Detector: Professional ultrasonic leak detectors can detect tiny leaks that are inaudible to the human ear, with high efficiency and accuracy.

Prompt Repair: Once a leak is discovered, repair it immediately. Tighten loose joints, replace aged or damaged seals, and repair or replace damaged pipes.

Optimize Piping Design: Minimize pipe joints, use welding or compression fittings instead of threaded connections, and select high-quality pipes and fittings.

Regularly Maintain Pneumatic Components: Regularly inspect and maintain pneumatic equipment and tools in the workshop to ensure proper sealing.

6.Excessive Gas Usage: A “Signal” of Overload, Reassessing Demand and Supply

In-Depth Analysis: This situation isn’t a malfunction of the air compressor itself, but rather a result of the factory’s actual compressed air demand exceeding the total exhaust capacity of the existing compressors. Common contributing factors include:

New Equipment: Adding new production lines, robots, pneumatic tools, etc., can lead to a sudden increase in total gas usage.

Production Process Adjustments: Increased compressed air demand or pressure requirements for certain processes.

Aging Equipment: Some older pneumatic equipment may exceed its design gas consumption due to issues such as poor sealing.

Unnecessary Gas Usage: Unclosed air guns, untimely pipe purging, and leaks.

When gas usage exceeds the compressor’s supply, system pressure continues to drop, causing pneumatic equipment to malfunction, resulting in “insufficient exhaust volume.”

Solution:

Accurately assess gas demand: Conduct a comprehensive survey of compressed air usage throughout the factory, measuring the gas consumption and operating hours of all equipment, and calculating peak and average gas usage. Optimize gas management:

Eliminate unnecessary gas use: Promptly shut down unused air guns and air blowing devices.

Optimize process parameters: Check the appropriate air pressure and flow settings in the production process to avoid excessive use.

Implement gas classification: Consider using compressors with different pressures to supply different air pressures, avoiding waste caused by high-pressure compressors serving low-pressure needs.

Add air compressors: If evaluation confirms that the total air capacity of the existing air compressors cannot meet actual demand, consider adding a new air compressor (usually a variable frequency air compressor to accommodate fluctuating loads) or replacing it with a compressor unit with a larger capacity.

Establish a centralized air supply system: For large factories, a centralized air supply system can better manage and distribute compressed air, improving efficiency.

7. Screw air compressor main unit failure: “Fatigue and damage” of core components requires professional inspection and repair.

In-depth analysis: The main unit of a screw air compressor is its core component, consisting of a pair of intermeshing male and female rotors that compress air through rotation. Any failure within the main unit will directly affect compression efficiency and air capacity. Common airend failures include:

Rotor wear: Long-term operation or the ingestion of impurities causes wear on the rotor surface, increasing the clearance between the rotor and the casing, leading to internal leakage and reduced compression efficiency.

Bearing wear or damage: Wear on the main bearing or thrust bearing causes unstable rotor operation, variable clearance, and even friction between the rotor and the casing, generating noise and high temperatures.

Shaft seal or oil seal failure: This leads to lubricant leakage, affecting airend lubrication and sealing, and even causing dry run.

Airend carbon deposits: Poor lubricant quality and high-temperature operation can cause carbon deposits inside the airend, affecting rotor meshing accuracy.

Airend failures are often accompanied by abnormal noise (such as sharp grinding or dull knocking sounds), increased vibration, increased exhaust temperature, and increased fuel consumption.

Solutions:

Professional diagnosis: Airend failures involve delicate mechanics, making them difficult for non-professionals to diagnose and repair. If you suspect an airend failure, immediately contact a professional air compressor service provider or manufacturer’s technicians for diagnosis.

Disassembly, inspection, and replacement: Professionals will use methods such as auscultation, endoscopic examination, and disassembly to determine the cause of the problem. Depending on the severity of the problem, the following may be necessary:

Replacement of bearings, shaft seals, and other components.

Perform an air conditioner overhaul, including cleaning and grinding the rotor, replacing worn parts, and adjusting clearances.

In severe cases, the entire air conditioner may need to be replaced.

Preventive maintenance: Regular air conditioner maintenance, using qualified lubricants, keeping the oil circuits clean, and avoiding air conditioner overload and prolonged high-temperature operation are key to extending air conditioner life.

Conclusion

Insufficient air volume in a screw air compressor is a complex issue that can be caused by a single factor or the combined effects of multiple factors. When faced with this problem, we should remain calm and systematically investigate each possible cause. By analyzing the seven major causes and detailed solutions provided in this article, combined with your specific situation, we believe you will be able to quickly identify and resolve the issue, ensuring efficient and stable operation of the air compressor and providing a solid foundation for the sustainable development of your business.

Remember, prevention is better than cure! Establishing a comprehensive system for daily inspection, regular maintenance, and servicing of your air compressor, and using genuine or recommended high-quality consumables, are the best ways to ensure long-term, reliable operation of your air compressor and avoid problems like insufficient air volume.