R-ProField casesCooling towers

Insufficient Fan Airflow — Belt Slip / Blade Pitch Misadjustment

Likely causes

V-belt elongation/wear causing slip — airflow reduction 10–25%

Check: Measure deflection under 10 N at mid-span — >10 mm = replace and adjust tension; check for slip residue (black dust)

What to do: Replace or re-tension belt → re-check after 4 h post-replacement (initial stretch) → verify RPM with stroboscope

Blade pitch angle below design or hub bolt loosening

Check: Measure blade pitch angle with inclinometer — verify within ±1° of design (typically 10–12°)

What to do: Readjust pitch → re-torque hub bolts (M10: 35–40 N·m) → verify current and vibration

Bearing wear/poor lubrication increasing fan rotation resistance

Check: Measure bearing outer temp (non-contact) — stop immediately if >70°C; vibration (accelerometer) — replace if >10 mm/s

What to do: Add grease (3–5g) → replace if no improvement → use IP55+ motor (mandatory for humid cooling tower environment)

Field tip

After belt replacement, re-check tension after 4 hours of operation mandatory. New belts lose tension quickly due to initial elongation.

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