9 tips for inspecting and maintaining blower fans

Article details

9 tips for inspecting and maintaining blower fans

Inspecting and maintaining a blower fan extends its service life. Here are our recommended tips in 9 ways

1. Impeller

1.1. Inspect annually for foreign matter or dirt lodged on the impeller. Deposits can cause vibration, wobbling and imbalance, wearing the bearings and pulleys and shortening their service life.

1.2. Check the impeller for rust, corrosion or damage. If it remains serviceable, repaint it and carry out ( balance) impeller balancing again.

1.3. Clean the impeller annually, especially forward-curved impellers ( forward curve ) whose blades curve forward. Heavy dirt buildup reduces airflow or causes imbalance, accelerating bearing wear and shortening bearing life.

2. Bearings

2.1. Check whether the bearing grease has dried out, and grease regularly every 1,000  hours. Use a suitable amount: replenish what is missing. If old grease overflows from the bearing, wipe it all away; otherwise the overflow can pick up dust or dirt and carry it into the bearing, shortening its service life.

2.2. Check for bearing noise and abnormally high temperature. Normal bearing temperature should not exceed 70 degrees Celsius   Abnormal bearing noise and heat can be caused by excessive belt tension or worn-out bearings. Bearing service life is 5   years. Continuing to use bearings beyond their service life can cause seizure and even shaft wear.

3.  Pulleys

3.1. Inspect pulleys annually to ensure they remain in normal serviceable condition. Pulley service life is 7   years   Whether a pulley lasts the full 7   years depends on belt adjustment. Belts should not be too loose, because this causes slipping ( slip ) during fan startup, wearing the pulley and shortening its service life.

3.2. Whenever replacing a pulley, check that it is smooth, with no chips, bumps or pits along the groove. The pulley must have undergone ( balance ) before use.

4. Belts

4.1. Check belt tension and readjust the belts every 2000 hours, or approximately every 3 months / time 4.2. All belts must have equal lengths and tension. Check tension by pressing a belt with your thumb. A deflection of approximately 1   centimeters, or about the belt's thickness, indicates suitable tension. Do not set belts too tight or too loose. Excessive tension can cause high temperature ( overheating ) in the bearings or bend the shaft over time. Loose belts may slip off the pulleys or slide, causing fan vibration and noise and accelerating pulley and belt wear.

4.3. Belt service life is 3   years  ( If a belt has reached the end of its service life or is worn, replace it immediately.)

5. Shaft

5.1. Check for shaft wear, especially at the bearing and impeller hub locations. Continuing to use worn-out bearings can cause them to seize and wear the shaft. Replace a worn shaft; continuing to use it can quickly damage the bearings.

5.2. Check that the shaft and impeller hub remain securely locked together. If their screws or bolts have loosened or are not tightened securely, the shaft and hub can wear.

5.3. Repaint the shaft if rust develops.

6. Structure

6.1. Inspect the fan structure annually for rust and corrosion. Repaint if rust is present.

Note
Fans installed near the sea, cooling towers or chemicals suffer structural corrosion and deterioration faster than under normal conditions.

7. Motor

7.1. Check whether the current is abnormally high compared with the initial setting. If there is overcurrent ( Over load )

7.2. Possible causes include expired or broken bearings, which raise the motor temperature and cause   the current to rise too. Normal motor temperature should not exceed 100 – 120   degrees Celsius. Replace bearings immediately at the end of their service life; continued use can cause seizure and burn out the motor. Bearing service life is 5   years. Motor service life is 15   years. After 15   years of operation, replace the motor or rewind the old motor before returning it to service.  

8.  Vibration

8.1. Fan vibration has several causes, which can be identified as follows:

8.2. Impeller imbalance: dirt, dust and foreign matter on the blades make the impeller wobble and oscillate.

8.3. Shaft wear: wear may occur at the impeller hub, bearing locations or pulley attachment.   This can cause fan vibration.

8.3. Belts   Belts that are too loose can slip or jerk during fan startup, causing vibration.

8.4. Pulley wobble: wobbling pulleys, worn pulley bores or inadequate balancing cause imbalance and fan vibration.

8.5. These are some of the causes of fan vibration. Inspect thoroughly and correct the actual cause to stop the vibration.

9. Nuts and screws (securing the fan structure)

9.1. Check all nuts and screws securing the fan structure, motor base, bearing housings, pulley belt guards and the impeller hub to the shaft. Check for looseness and tighten every nut and screw securely.  

9.2. Fans installed where oil vapor is present, or used to extract oil vapor, should be checked regularly because oil can cause nuts and screws to loosen.

9.3. Regular inspection and maintenance following the ventilation fan maintenance schedule reduce long-term repair costs and extend fan service life.