Cooling Tower Filler Cleaning

1. Cleaning Filler in Crossflow Cooling Towers

Cleaning the filler in crossflow towers is relatively simple. Maintenance personnel can connect a water pump and rinse it directly with water. If rinsing is insufficient and there is significant scaling inside the filler, you can insert a stick between two filler sheets, shake it up, down, left, and right to loosen the deposits, and then flush thoroughly with a strong water flow. This method usually solves the problem.

2. Cleaning Filler in Counterflow Cooling Towers

Cleaning the filler in counterflow towers is more complicated and costly. The filler must be separated from the tower body and undergo soaking, flushing, and other procedures. Moreover, since the filler is installed in stacked layers, it is difficult to visually inspect scaling conditions.

This leads to a common question: When should counterflow cooling tower filler be cleaned, and what is a reasonable cleaning cycle?
Currently, there is no industry-wide standard. Manufacturers typically recommend annual cleaning, while some maintenance teams clean every three years, and others claim they've been running for five years without cleaning and have had no issues. So, what should be done?

I. How to Determine When Counterflow Cooling Tower Filler Needs Cleaning

A practical method is to monitor the fan motor current. If the fan’s operating power drops significantly, it indicates airflow is restricted due to clogged filler.
For example, if the cooling tower uses a 22 kW motor, but at full frequency it only draws 15 kW, this suggests a substantial reduction in ventilation capacity — meaning the filler is heavily blocked and should be cleaned.

II. Cleaning Quality Standards: When Is Filler Considered Clean?

Some cleaning service providers claim they can remove 80% of the deposits, but this is not acceptable for two reasons:

Ambiguity – “80% clean” is too vague and cannot be reliably measured.

Residual Scaling – If 20% of deposits remain, the filler surface becomes rougher, accelerating future scaling.

Therefore, filler should be thoroughly cleaned, or else replacement is preferable.

Recommended Methods to Verify Cleaning Quality:

Weight Comparison Method
Take random samples and weigh them. After cleaning, the filler weight should differ from that of new filler of the same specifications by no more than 2%. This ensures that impurities have been removed effectively.

Visual Inspection
The filler surface should be free from visible scale, biofilm, or sludge, and channels should be unobstructed.

Precautions: Avoid Secondary Damage

Do not use corrosive acidic cleaners like hydrochloric acid.

If acidic cleaning is necessary, only safe organic acids, such as citric acid, should be used.

After cleaning, ensure thorough neutralization to prevent corrosion of the tower body and filler.

III. Post-Cleaning Acceptance: How to Verify Performance After Reinstallation

After cleaning and reinstalling the filler, the following checks should be performed:

Fan Operation Consistency
Compare the fan motor currents and power consumption across all towers. Readings should be consistent and close to rated specifications. This indicates normal airflow and proper filler resistance.

Drift Eliminator Performance
Ensure the drift eliminator is working correctly with no noticeable water carryover.

Water Temperature Uniformity
The temperature difference between different regions of the cooling tower basin should not exceed 1 °C. Uniform temperatures indicate effective heat exchange and restored filler performance.

Chloride Testing (if acidic cleaners were used)
If chlorine-based cleaners were applied, test the water for chloride ion concentration, which should remain below 20 mg/L to avoid corrosion of metal components.