TL;DR
Basin sediment accumulates when blowdown rate is too low or the side-stream filter is undersized or bypassed. Clean the basin, increase blowdown, and restore the filtration program.
What you might see
- visible sludge or sand-like deposits in basin
- strainer clogging more frequently than normal
- turbid circulating water
- pump suction losing flow intermittently
Likely causes
Insufficient blowdown allowing suspended solids to concentrate and settle
Clogged or bypassed side-stream filtration not removing fine particles
Airborne dust and debris entering the open basin
Biological die-off and scale flakes from an inadequate treatment program
Required tools
- LOTO kit
- Basin vacuum or scoop
- Conductivity meter
- Replacement filter media or cartridges
- Hose for flushing
Safety first
- Basin sludge may contain biological hazards. Wear gloves and eye protection when removing sediment.
- Lock out the pump before reaching into the strainer or basin piping.
Procedure
- 1
Lock out the fan motor and circulating pump.
Warning: Confirm zero pressure on the pump discharge before opening any connections. - 2
Reduce basin water level to the minimum and manually remove settled sludge with a basin vacuum or scoop.
- 3
Flush the basin with clean water and remove loosened debris.
- 4
Inspect the pump suction strainer and clean it. Note what debris type dominates (scale, biological, airborne dirt) to guide root-cause correction.
- 5
Inspect the side-stream filter media or cartridge. Replace or backwash if saturated.[1]
- 6
Adjust the blowdown controller setpoint. Target conductivity per your water treatment provider's recommendation, typically 1500-2500 microsiemens/cm depending on makeup water quality.
- 7
Refill the basin and restore normal operation.
- 8
Re-inspect the basin after 7 days and compare sediment accumulation to baseline.
Sources
Marley NC Cooling Tower User Manual, Marley Cooling (SPX Cooling Technologies)
Marley NC Cooling Tower Installation, Operation and Maintenance manual, basin maintenance and filtration procedures (general)
View source
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