Inspection of axial fans for commissioning is a critical step in ensuring the efficiency, safety, and reliability of industrial and HVAC systems. As part of a deeper dive into equipment manufacturer’s literature, I’ve put together an overview of the procedure for inspecting axial fans with the goal of prolong the equipment life, reducing energy consumption, and maintaining optimal system performance. After commissioning is complete, regular inspections and maintenance will go a long way in preventing costly downtime and ensuring a safe working environment.

Safety Precautions: Before beginning the inspection, ensure the fan and the surrounding area are safe to access. At a local disconnect or using lock-out-tag-out (LOTO) at the breaker, shut off power to the fan to prevent accidental start-ups during inspection.

General: Start with an overall visual inspection of the fan casing, motor, blades, enclosure, and ductwork to look for signs of wear and tear, corrosion, damaged parts, and loose or missing fasteners. Verify there is no debris or obstructions that could interfere with the fan blades.  Manufacturers often require 1-2 equivalent diameters of free, straight length of duct on the fan inlet.  This allows for uniform entry of air across the face of the fan and prevents noise, vibration, and wear and tear.

Bearing Check: Examine the fan’s bearings for signs of wear or overheating. Reference the maintenance schedule and manufacturer’s recommendations to determine if they need lubrication.

Blade Inspection: Carefully inspect the fan blades for any cracks, warping, or imbalance. Even minor damage can significantly affect performance. Ensure the propeller set screw is tight. Rotate the propeller by hand to verify it does not strike the venturi or any obstacle.

Alignment Verification: Ensure that the fan is correctly aligned with the motor and the surrounding ductwork. Misalignment can lead to vibration and premature wear.

Electrical Components: Check all electrical components, such as switches, relays, and control panels, for proper operation and connections. Reference the manufacturer’s installation instructions and motor nameplate to determine the most suitable overcurrent protection for your fan motor.  For example, Greenheck recommends a Miniature Circuit Breaker (MCB) sized for 1.5 times the Full Load Amps (FLA) of the motor. Ensure that electrical connections are secure and the power cable is not kinked or damaged. The motor and fan housing must be properly grounded to a suitable electric ground, such as a grounded water pipe or ground wire system.

Running Test: “Bump” the fan and verify the direction of rotation matches the arrow in the motor compartment.  With the fan running, check noise levels. Unusual or excessive noise can indicate problems with the blades, bearings, or motor.

Documentation: Maintain thorough records of the inspection process, including any issues identified and the actions taken to address them. This documentation can be invaluable for future reference and maintenance.

Conclusion: Based on the results of the inspection, make recommendations for any necessary repairs or adjustments, and address these issues promptly to ensure the fan operates at its best. Final Testing: After any repairs or adjustments are made, conduct a final round of testing to confirm that the fan now meets performance specifications.