Cooling tower quarterly preventive maintenance plan

Tasks at each service

1. 1

   Review the water treatment records and the latest results

   Check the logbook since the last service: dosing, conductivity, bleed-off, and the latest Legionella and total bacteria results. Any result above the action level of the site’s risk assessment calls for the corrective actions it defines.

   Verification20 min
2. 2

   Inspect the drift eliminators

   Check that every eliminator section is in place, undamaged, clean and fitted without gaps: a missing or broken section lets contaminated droplets escape.

   Inspection15 min

   Risks: Isolate and lock out the fan before entering the tower. Wear a respirator suited to aerosols when the water circulates.

3. 3

   Inspect the fill and the water distribution

   Look for scale, biofilm, algae and collapsed fill, and check that the nozzles or the hot water basin spread the water evenly with no blocked outlet.

   Inspection15 min

   Risks: Isolate and lock out the fan before entering the tower.

4. 4

   Inspect the basin

   Look for sludge, debris, algae and corrosion in the basin, and check the make-up valve, the overflow and the basin strainer.

   Inspection15 min
5. 5

   Inspect the fan and its drive

   Check the blades and hub for erosion and cracks, the blade tip clearance, the guard, the belts or the gearbox oil level, and the fan vibration switch where fitted.

   Inspection20 min

   Risks: Isolate and lock out the fan motor before entering the fan deck; the fan can windmill in the air flow: block it.

6. 6

   Grease the fan bearings (regreasable bearings only)

   Grease the fan shaft and motor bearings with the grease type and quantity given by the manufacturer.

   Action10 minoptional

   Tools: Grease gun

7. 7

   Check the bleed-off and the dosing equipment

   Check that the bleed-off valve opens at the conductivity setpoint, compare the conductivity meter with a calibrated hand meter, and check that the dosing pumps run and the product tanks are not empty.

   Verification20 min

   Tools: Hand-held conductivity meter

   Risks: Wear gloves and eye protection near the treatment chemicals.

8. 8

   Drain, clean and disinfect the tower

   At least once a year, twice in some countries, at the frequency set by the risk assessment or local regulation: disinfect before draining, drain, remove sludge and deposits from the basin, fill and eliminators, then refill, disinfect again and restart the treatment. Record the products, contact times and residuals.

   Action480 minonce every 4 services

   Risks: Aerosols can carry Legionella: wear a respirator suited to aerosols and protective clothing, and keep other people away from the tower during the work.

9. 9

   Restart and record in the logbook

   Restart the fan and the circulation, check for abnormal noise and vibration, then record the findings in the work order and the tower’s logbook.

   Verification10 min