Common Faults and Troubleshooting Methods for Air-Suspension Blowers: A Comprehensive Analysis and Practical Guide

Common Faults and Troubleshooting Methods for Air-Suspension Blowers: A Comprehensive Analysis and Practical Guide

Air-Suspension Blower Owing to their high efficiency, energy savings, oil-free operation, and low maintenance costs, air-suspension blowers are gradually replacing conventional roots blowers and multistage centrifugal blowers, emerging as critical power equipment in industries such as wastewater treatment, cement production, chemical manufacturing, and textile dyeing. However, “maintenance-free” does not equate to “requiring no attention.” As technology-intensive rotating machinery, air-suspension blowers still encounter a variety of operational challenges and failures in daily use. Drawing on engineering practice, this paper systematically reviews the common failure modes of air-suspension blowers, thoroughly analyzes their underlying mechanisms, and presents practical diagnostic methods and remedial strategies.

I. Bearing System Failure: The Core of the Core

The air-bearing is the most critical and precision component of an air-suspension blower, and its condition directly affects the overall performance and service life of the equipment.

1.1 Abnormal Bearing Noise

Fault symptoms : Sharp whistling, piping sounds, or metallic clanging and clicking noises occur during operation.

Mechanism Analysis ：

• Sharp screech/whistle : Typically caused by instability of the bearing air film or insufficient supply pressure. When a high-speed rotating rotor fails to establish a stable air film, localized contact occurs between the shaft and the bearing surface, generating high-frequency friction noise. Friction between the impeller and the casing can also result from the same underlying cause.
• Metallic impact sound / clicking sound : This is often caused by bearing wear, excessive air-film clearance, or loosening of internal components (such as foil detachment in air bearings).
• Metallic screeching during the start-stop phase (3–8 seconds) During the low-speed start-up and shutdown phases of equipment, the gas film has not yet fully formed or is in the process of dissipating, resulting in direct contact between the shaft and the bearing—known as “dry friction.” Over time, this condition can cause scoring on the inner raceway surface of the bearing, significantly reducing its service life.

Handling method ：

1. Precisely locate the sound source using a stethoscope or acoustic stethoscope.
2. To mitigate the screeching noise during start-up and shutdown, avoid frequent cycling; ensure that the bearing housing is adequately preheated before startup, and maintain purging for 3–5 minutes after shutdown to facilitate the dissipation of the gas film.
3. If abnormal noise persists and gradually increases, the equipment must be shut down immediately for inspection to prevent bearing seizure and subsequent impeller damage.

1.2 Excessive Bearing Temperature

Fault symptoms : Bearing temperature exceeds the normal range (typically ≤70°C), or the temperature rises sharply within a short period of time (e.g., by more than 10°C within 10 minutes).

Mechanism Analysis ：

• Gas supply pollution : Oil or water ingress into the bearing system leads to lubricant failure, causing the bearing to operate in a “wet” or “contaminated” gas film, which results in a sharp increase in the coefficient of friction.
• Increased bearing wear : The air-film gap has abnormally increased due to long-term operational wear, or the foil pads of the air bearing have deformed, leading to reduced air-film stability.
• Cooling System Failure : The cooling fan has stopped rotating, and the airflow duct is blocked, resulting in the inability to promptly dissipate heat from the bearing system.
• Dust-sensitive intake : Dust clogs the bearing throttling orifices, thinning the gas film and thereby further inducing frictional heating.
• Overload operation : When equipment is subjected to forces exceeding its design load, the bearing experiences increased stress and friction, generating excessive heat. High temperatures degrade the bearing’s lubrication performance and hardness, thereby accelerating bearing aging and failure.

Handling method ：

1. Inspect the oil mist separators and dryers in the gas supply system to ensure that the filtration accuracy meets the required specification of ≤0.1 μm.
2. Install high-precision filtration in the intake duct to control the dust concentration in the inlet air to below 0.1 mg/m³.
3. Regularly clean the radiator and air ducts to ensure proper ventilation.
4. If the unit frequently trips due to high summer temperatures, the bearing restrictor orifice should be cleaned with ultrasonic cleaning every three months.
5. Monitor equipment operating load to prevent prolonged overload.

1.3 Vibration Values Exceed the Limit

Fault symptoms : Vibration levels exceed the manufacturer’s specified threshold (typically ≤2.5 mm/s), resulting in unstable equipment operation and an upward trend in vibration levels.

Mechanism Analysis ：

• Installation Foundation and Piping Issues : Uneven equipment foundations, loose anchor bolts, damage or distortion of inlet and outlet flexible connectors, or inadequate pipe supports can all impose excessive stress on the fan inlet and outlet flanges.
• Dust accumulation on the impeller or loss of dynamic balance : The high-speed impeller, due to humid intake air and oil contamination, gradually accumulates dust or scale on its surface, disrupting dynamic balance.
• Abnormal bearing operation : Instability of the bearing air film or bearing wear leads to rotor misalignment during operation.

Handling method ：

1. Check the levelness of the installation foundation and tighten the anchor bolts.
2. Inspect the condition of flexible pipe connections, install expansion joints at rigid pipe connections, and verify with a dial indicator before commissioning that flange misalignment does not exceed 0.5 mm.
3. Every six months, the impeller shall be blast-cleaned with dry ice to remove surface contaminants without damaging the coating.
4. If the impeller is severely damaged, dynamic balancing tests must be performed, or a professional repair service should be contacted.

II. Surge: The “Kill Switch” for Centrifugal Fans

Surge is one of the most detrimental and最难完全杜绝 (most difficult to completely eliminate) fault types in the operation of air-suspension blowers, and therefore requires close attention.

2.1 Identification and Mechanism of Surge

Fault symptoms : Severe equipment vibration, fluctuating airflow, abrupt current fluctuations, and abnormal noise (such as a “buzzing” or “explosive” sound).

Mechanism Analysis : Surge is, in essence, an unstable operating condition that occurs in centrifugal compressors under low-flow conditions. When the resistance in the discharge piping is excessively high, too many valves are closed, the aeration heads become clogged, or the water level rises suddenly—causing the fan’s operating point to shift leftward and cross the surge line—periodic backflow of air ensues. In this “compression–backflow–re-compression” cycle, the impeller dissipates energy and is unable to discharge air normally. Centrifugal fans all have inherent performance curves and safe operating ranges; once these limits are exceeded, surge will inevitably occur.

2.2 Main Causes of Surge

1. Insufficient airflow : The gas consumption on the demand side is far below the fan’s rated minimum airflow, resulting in a significant imbalance where the inlet airflow exceeds the outlet airflow.
2. Excessive pipeline network resistance : The outlet valve is closed, the pipeline is blocked, or the aeration heads experience increased resistance after prolonged operation.
3. Seal clearance increases : After prolonged operation, the clearance in the seal gap increases, leading to intensified gas backflow and making surge more likely to occur at low flow rates.
4. Equipment selection is oversized. The fan’s specifications significantly exceed the actual requirements, making it highly susceptible to surge under low-load conditions.

2.3 Handling and Prevention of Surge

Emergency Handling ：

1. Quickly open the anti-surge device valve (such as a vent valve) to promptly bring the fan out of the surge condition.
2. Adjust the fan’s operating point by increasing the opening of the inlet control valve or decreasing the opening of the outlet valve.
3. Reduce the fan load, for example by adjusting the motor speed, to minimize surge-induced damage to the fan.

Precautions ：

1. Recalculate the pipeline network resistance curve and appropriately reduce the surge prevention valve opening pressure (by 5–8 kPa).
2. Install a recirculation loop on the pipeline to ensure that the fan always operates within the range of ≥30% of its rated flow.
3. Optimize and commission the control system to ensure the effectiveness of the anti-surge control logic.
4. Regularly inspect pipeline flow integrity and aeration head condition to prevent sudden changes in system resistance.

III. Motor and Electrical Control System Faults

High-speed permanent-magnet synchronous motors serve as the power source for air-suspension blowers, and their reliability directly affects the continuous operation of the equipment.

3.1 Motor Fails to Start

Fault symptoms : After pressing the start button, the motor shows no response, or it automatically shuts down shortly after starting.

Mechanism Analysis ：

• Power System Abnormality : Three-phase voltage imbalance (deviation exceeding 5%), phase loss, and overcurrent tripping due to open circuits or overloads, among others.
• Control signal interruption : Loose remote control wiring, abnormal PLC output signal, or a fault in the local control panel.
• Protection interlock trigger : The emergency stop button has not been reset, the bearing temperature sensor is falsely alarming, and the overload protection threshold is set too low, among other issues.
• Hardware blocking : Severe clogging of the intake air filter resulting in excessive negative pressure, or the presence of foreign objects jammed inside the equipment.

Handling method ：

1. Use a multimeter to verify that the input voltage (380 V three-phase power) is within specifications, and check the status of the circuit breakers in the distribution panel.
2. Check whether the remote control wiring and signal module are functioning properly.
3. Confirm that the emergency stop button has been reset and that the temperature and pressure sensors are functioning properly.
4. Clean the air intake filter and inspect the impeller for any foreign objects.

3.2 Overheating Shutdown During Motor Operation

Fault symptoms : If the motor temperature continuously rises above the rated value, the thermal protection will trip and shut down the motor. After shutdown, the fan may continue to run (some models are equipped with a built-in cooling fan).

Mechanism Analysis ：

• Poor heat dissipation : The heat sink is clogged with dust, the cooling fan is damaged or spinning in the wrong direction, resulting in failure of heat dissipation.
• Overloaded : Operating conditions exceed the equipment’s rated capacity (e.g., an abnormal rise in the aeration tank water level leads to a sharp increase in air pressure demand), causing the motor to operate under high load for an extended period and resulting in elevated temperatures.
• Environmental Issues : The equipment is installed in a high-temperature environment (e.g., a factory workshop with summer temperatures ≥40°C), where the ambient temperature significantly reduces cooling efficiency.

Handling method ：

1. Use a brush to remove dust from the heat sink fins, check that the cooling fan is operating normally, and verify that the fan is rotating in the correct direction.
2. Reduce the output load or adjust process parameters via the control panel.
3. Increase ventilation in high-temperature environments (e.g., by installing exhaust fans or air conditioning), or install thermal insulation shields on the motor housing.

3.3 Inverter Communication Abnormality

Fault symptoms : The touch screen or control panel displays an alarm indicating inverter communication failure, inverter error, or sudden shutdown of the fan during operation.

Mechanism Analysis : Sensor and data communication anomalies, internal inverter faults, or interruptions in the PLC communication cable and MODBUS protocol.

Handling method ：

1. Check that the communication cable connections are secure and that signal transmission is functioning properly.
2. Confirm the status of the inverter’s power indicator light and inspect the cooling air ducts for dust accumulation.
3. For any issues related to the variable frequency drive, please contact the manufacturer’s technical personnel to avoid disassembling it yourself, which could complicate repairs.
4. In cases where the same alarm message recurs frequently within a short period, contact the manufacturer promptly to prevent more serious equipment failures.

IV. Filtration System and Air Intake Issues

The filtration system serves as the first line of defense for air-suspension blowers against environmental corrosion.

4.1 Filter Clogging and Differential Pressure Alarm

Fault symptoms : The control panel displays a high differential pressure alarm or a filter clog alarm, accompanied by reduced airflow and increased energy consumption.

Mechanism Analysis : If the intake air filter is not cleaned or replaced for an extended period, dust and debris will accumulate on the filter surface, increasing intake resistance (to the point where it exceeds the differential pressure limit). With restricted airflow, the fan’s intake volume decreases; to maintain the same output airflow, the motor must consume more energy, creating a vicious cycle.

Handling method ：

1. Blow compressed air at low pressure from the inside of the filter element outward (taking care not to damage the filter material) to remove surface dust.
2. Recommended maintenance schedule: The primary filter cotton should be inspected and cleaned weekly and replaced approximately every 15 days; the HEPA filter should be inspected monthly and replaced approximately every 3 months.
3. When replacing the filter element, ensure a tight seal to prevent unfiltered air from being drawn in directly.
4. After replacement, the alarm messages on the touch screen must be reset before the equipment can be restarted.

4.2 Inlet Air Quality Does Not Meet Standards

Fault symptoms : Frequent equipment alarms, accelerated bearing wear, and continuous efficiency decline.

Mechanism Analysis : Contaminants such as oil, moisture, and dust in the intake air can adhere to the high-speed impeller and bearing system upon ingestion, which is one of the primary causes of bearing lubrication failure.

Handling method ：

1. Install a fine filtration unit on the intake air duct, and configure an oil mist separator and a dryer as required.
2. In applications with high humidity, such as aeration rooms in wastewater treatment plants, a synthetic-fiber mist-removal mat should be installed at the air intake to reduce humidity.
3. Regularly inspect the area around the air intake for debris and keep it clean.

V. Abnormalities in the Piping System and Airflow/Air Pressure

5.1 Insufficient Air Volume or Static Pressure

Fault symptoms : Equipment operating parameters are normal, but the output airflow and static pressure have not reached the set values, failing to meet production process requirements.

Mechanism Analysis ：

• Gas transmission line leakage/blockage : Leakage caused by aging of sealing gaskets at pipe welds and flanged connections; scaling inside aeration pipes reducing the flow diameter; and check valves becoming stuck, impeding gas flow.
• Impeller performance degradation : A large amount of dust has accumulated on the blade surfaces, altering their aerodynamic performance; after prolonged operation, the blade edges become worn, resulting in a 15%–20% reduction in airflow.
• Insufficient motor speed : The inverter output frequency has not reached the set or calculated value, resulting in a decrease in speed.
• Control signal parameter anomaly : Pressure/flow sensors drift over prolonged operation, resulting in inaccurate measurement data and erroneous control system decisions.

Handling method ：

1. Systematically inspect the piping, valves, and flanged connections between the fan outlet and the process point for air leaks.
2. Clean or replace the air intake filter to eliminate airflow resistance.
3. Inspect the pipeline for scale buildup and clean and inspect it as necessary.
4. Inspect the sensor calibration and verify that the control system parameter settings are aligned with the current operating conditions.

5.2 Piping Stress Fault

Fault symptoms : Abnormally high vibration levels after equipment startup, potentially triggering over-limit alarms and causing shutdown; failure of the flange connection seal or leakage.

Mechanism Analysis : The piping system lacks expansion joints or flexible connections, causing the thermal expansion and contraction stresses in the pipeline to be directly transmitted to the equipment itself. This can result in the fan mounting foundation being “pushed out of alignment” or flange misalignment, which in turn leads to excessive vibration and abnormal bearing operation.

Handling method ：

1. A flexible connection shall be used at the interface between the ductwork and the fan to minimize stress transmission.
2. Prior to commissioning, the flange misalignment shall be verified using a dial indicator to ensure that the misalignment does not exceed 0.5 mm.
3. Pipeline supports shall be designed appropriately to prevent the self-weight of the pipeline from imposing suspended loads on the fan inlet and outlet connections.

VI. “Soft Faults” in Operation and Maintenance and Their Prevention Strategies

6.1 Wear from Frequent Start-Stop “Dry Grinding”

During each start-up and shutdown, there is a 3- to 8-second period of low-speed “dry running,” which has the most significant impact on the service life of air-bearing systems. Frequent starts and stops should be avoided; instead, a “24-hour continuous operation with variable-frequency load reduction” mode is recommended over a control strategy that relies on frequent on-off cycling. High temperatures, meanwhile, act as a “chronic poison” for the bearings, necessitating strict temperature control through measures such as improving ventilation and regularly cleaning the heat exchangers.

6.2 Preventive Maintenance Framework

1. Operational Status Monitoring : Continuously monitor equipment condition using vibration analyzers and sound level meters to ensure that vibration levels remain below the manufacturer’s specified threshold (typically ≤2.5 mm/s); during normal operation, the noise should be a steady “hum” with no noticeable extraneous sounds.
2. Regular inspections : Daily check that the operating current, temperature, vibration, and air pressure and volume are within normal limits.
3. Maintenance Record Management : Establish detailed maintenance records for each piece of equipment, documenting model specifications, installation details, inspection data, and troubleshooting outcomes, to enable data-driven preventive maintenance.
4. Reasonable Parameter Configuration : Ensure that the setpoints for start-up wind pressure and flow do not exceed the equipment’s rated values, and that the PID control parameters are properly matched to the operating conditions.
5. Establishment of a coordination mechanism : Establish long-term maintenance and service agreements with reputable manufacturers, leveraging the technology provider’s remote health monitoring and preventive maintenance services to proactively identify risks.

VII. Summary and Outlook

The core failures of air-suspension blowers can be categorized into five main types: Bearing system failures, surge, motor electrical faults, filtration system issues, and abnormal airflow and pressure in the piping system. Among these failures, bearing wear and surge pose the greatest threats to equipment service life, while frequent start–stop cycles and intake air contamination are the primary drivers of damage accumulation.

Understanding the failure mechanisms of equipment is only the first step toward ensuring stable operation. Deeper-level management lies in routine inspections and scientifically sound operations and maintenance. While relying solely on alarm signals can help plug these gaps, the true secret to extending equipment life is not reactive repair—it’s proactive fault prevention at the source: replacing frequent startups with continuous operation, using filtered intake air to eliminate dust contamination, and unlocking equipment potential through data-driven O&M practices.

With the deepening integration of IoT, artificial intelligence, and big data technologies in the industrial equipment sector, future air-suspension blowers will achieve more intelligent self-diagnosis and self-optimization capabilities. By leveraging real-time analysis of operational data and proactive fault prediction, these blowers will transition from “on-demand maintenance” to a new paradigm of “predictive maintenance.” Nevertheless, regardless of how technology evolves, a thorough understanding of the failure mechanisms of air-suspension blowers and robust on-site diagnostic skills will remain the core competencies of operations and maintenance personnel.