How To Change Filter Media in A Bac Cooling Tower

Below is a clear, step-by-step field procedure for changing filter media in a BAC cooling tower, written the way service technicians and plant engineers actually do it.

*(This applies to BAC towers with basin strainers, side-stream filters, or cartridge/media filters—BAC itself does not use “filter media” inside the fill.)*

1. Identify the Filter Type First (Very Important)

BAC cooling towers typically use one of these three filtration setups:

1️⃣ Cold-water basin strainer / screen

2️⃣ Side-stream filter (sand, multi-media, or cartridge type)

3️⃣ In-line Y-strainer or basket strainer

> ❗ BAC fill packs are **NOT filter media** and should never be treated as such.

2. Safety & Preparation

✔ Lock out / tag out (LOTO) condenser water pump

✔ Stop cooling tower fan

✔ Close isolation valves to the filter

✔ Allow pressure to drop to zero

✔ Wear PPE (gloves, eye protection)

3. Changing Media in a Side-Stream Filter (Most Common)

Step 1: Isolate the Filter

* Close inlet and outlet valves

* Open drain valve to empty the vessel

Step 2: Open the Filter Vessel

* Remove top cover / manway

* Inspect internal laterals and screens

Step 3: Remove Old Filter Media

* Vacuum out or shovel spent media

* Flush remaining fines with clean water

* Check for:

 * Broken laterals

 * Cracked nozzles

 * Corrosion

Step 4: Add New Filter Media (Correct Order)

Typical BAC-compatible multi-media arrangement:

Layer (Bottom → Top)	Media Type
Support layer	Gravel
Intermediate	Coarse sand
Fine filtration	Fine sand / anthracite

> Follow the filter manufacturer’s media depth, not BAC’s.

Step 5: Reassemble & Backwash

* Reinstall cover with new gasket

* Slowly fill filter with water

* Perform backwash until discharge runs clear

4. Changing Cartridge Filter Media

Step 1: Isolate & Drain

* Close valves

* Open drain and vent

Step 2: Remove Old Cartridges

* Open housing

* Pull out cartridges

* Inspect O-rings and seats

Step 3: Install New Cartridges

* Lubricate O-rings

* Install with correct orientation

* Torque cover evenly

Step 4: Flush System

* Slowly re-pressurize

* Check for leaks

* Flush to drain for several minutes

5. Cleaning / Replacing Basin Strainer (No Media)

* Remove strainer basket or screen

* Wash with clean water or mild detergent

* Replace if damaged or corroded

* Reinstall securely

6. Restart Procedure

1️⃣ Open isolation valves

2️⃣ Start side-stream pump

3️⃣ Check pressure differential

4️⃣ Start condenser water pump

5️⃣ Start cooling tower fan

6️⃣ Verify normal basin level

7. How Often Should Filter Media Be Changed?

Filter Type	Typical Interval
Sand / multi-media	2–5 years
Cartridge	3–12 months
Basin strainer	Clean monthly

*Frequency depends on water quality and blowdown control.*

8. Common Mistakes to Avoid ⚠️

❌ Treating fill as filter media

❌ Skipping backwash after media replacement

❌ Using incorrect media size

❌ Restarting pumps too quickly

❌ Ignoring broken laterals/screens

9. BAC Best-Practice Recommendation

BAC strongly recommends:

* Side-stream filtration (5–10% of system flow)

* Proper chemical treatment

* Regular basin cleaning

This protects fill, spray nozzles, pumps, and heat exchangers.