Cooling Tower Water Filtration Systems

A cooling tower water filtration systems is essential for keeping circulating water clean, protecting fill, spray nozzles, heat exchangers, and pumps, and maintaining thermal efficiency. Below is a clear, engineering-focused overview you can use for selection, design, or operation.

1. Purpose of Cooling Tower Water Filtration Systems

Filtration removes:

* Suspended solids (dust, sand, rust)

* Biological debris (algae, slime)

* Scale particle

Benefits

✔ Prevents nozzle blockage

✔ Keeps fill clean and wet

✔ Improves heat transfer

✔ Reduces chemical use & blowdown

✔ Extends equipment life

2. Main Types of Cooling Tower Filtration Systems

2.1 Side-Stream (Slip-Stream) Filtration ⭐ Most Common

Filters 5–15% of total circulating flow continuously.

Common filters

* Multimedia (sand) filters

* Disc filters

* Screen filters

Typical filtration: 10–50 microns

Best for: HVAC & industrial towers

2.2 Full-Flow Filtration

Filters 100% of circulation flow.

Advantages

✔ Maximum cleanliness

✔ Best protection for process equipment

 2.3 Centrifugal Separators (Hydrocyclones)

Remove heavy particles like sand and grit.

Advantages

✔ No filter media

✔ Minimal maintenance

2.4 Basin Sweeper Systems

Remove debris from the cold water basin.

Features

* Jet nozzles sweep solids toward drain or filter

* Used with side-stream filters, not alone

2.5 Cartridge / Bag Filters

Used for fine polishing or temporary applications.

Filtration range: 1–10 microns

Note: Higher maintenance cost

3. Comparison of Cooling Tower Water Filtration Systems

System	Micron Range	Cost	Maintenance	Best Use
Multimedia filter	10–40 µm	Medium	Low	General towers
Disc filter	5–20 µm	Medium	Low	Fine filtration
Screen filter	50–200 µm	Low	Very low	Large debris
Hydrocyclone	>75 µm	Low	Very low	Sandy water
Full-flow filter	5–25 µm	High	Medium	Critical systems

4. Cooling Tower Water Filtration Systems Design Parameters

Flow Rate

* Side-stream flow: 5–15% of circulation rate

* Basin sweeper: 3–5%

Pressure Drop

* Clean: 0.3–0.7 bar

* Backwash set point: 1.2–1.5 bar

Filtration Level

* HVAC towers: 25–50 µm

* Industrial/process towers: 5–25 µm

5. Typical Cooling Tower Water Filtration Systems Layout

Cooling Tower Basin

       ↓

Circulation Pump

       ↓

Side-Stream Take-off

       ↓

Filter System (Auto Backwash)

       ↓

Return to Basin / Make-up Line

6. Materials of Cooling Tower Water Filtration Systems Construction

* Housing: Carbon steel, FRP, or stainless steel

* Piping: PVC, HDG, SS

* Valves: PVC, brass, SS

Material choice depends on water chemistry and corrosion risk.

7. Automation & Controls Of Cooling Tower Water Filtration Systems

* Differential pressure switch

* Automatic backwash valve

* PLC / timer control

* Integration with chemical dosing

8. Common Problems & Solutions Of Cooling Tower Water Filtration Systems

| Problem                  | Cause                 | Solution                   |

| ------------------------ | --------------------- | -------------------------- |

| Frequent nozzle clogging | Filtration too coarse | Reduce micron rating       |

| High blowdown            | Excess solids         | Increase side-stream flow  |

| High pressure loss       | Dirty filter          | Improve backwash frequency |

| Algae in basin           | Poor debris removal   | Add basin sweeper          |

9. Selection Guidelines (Quick) For Cooling Tower Water Filtration Systems

✔ Use side-stream filtration for most cooling towers

✔ Select 25 µm for HVAC, 10 µm for process cooling

✔ Ensure automatic backwash

✔ Combine filtration with proper water treatment