Drift Eliminators: How They Reduce Water Loss in Cooling Towers 

What is a Cooling Tower? 

A cooling tower is a heat rejection device that removes excess heat from a building or industrial process by cooling a stream of water through evaporation. Warm water from the system is routed into the cooling tower and distributed over a large surface area, usually through fill material, while air is simultaneously drawn or forced through the tower. As the water and air interact, a small portion of the water evaporates, removing heat from the remaining liquid. 

Cooling towers are widely used in: 

• Power plants 

• Oil refineries 

• HVAC systems in commercial buildings 

• Petrochemical plants 

• Manufacturing industries 

There are two main types of cooling towers: wet (evaporative) and dry (air-cooled), but drift eliminators are most relevant in wet cooling towers, where water is directly exposed to airflow. 

What is Drift in Cooling Towers? 

Drift refers to tiny water droplets that get entrained in the air stream and escape from the cooling tower along with the exhaust air. Unlike evaporation (which is a designed heat-rejection process), drift is unintended water loss—and it can: 

• Waste thousands of gallons of water over time 

• Cause scaling and corrosion on nearby equipment and structures 

• Create environmental concerns, especially if the water contains treatment chemicals or harmful microorganisms like Legionella 

Drift losses typically account for 0.01% to 0.2% of the circulating water flow, but with large towers, even this small percentage can result in significant loss and cost. 

What Are Drift Eliminators? 

Drift eliminators are mechanical devices installed in cooling towers to capture water droplets from the air stream before they exit the tower. 

They are usually composed of corrugated PVC, polypropylene, or fiberglass sheets, arranged in a zigzag or maze-like pattern. As air flows through this path, it changes direction multiple times, causing water droplets to collide with the surfaces, coalesce, and drain back into the system. 

Drift eliminators can reduce drift loss to as low as 0.0005% of the circulating water flow, making them indispensable in large-scale, water-intensive operations. 

How Drift Eliminators Work? 

Here’s a step-by-step look at their function: 

1. Air-Water Mixture Entry: The upward air flow, saturated with moisture and small water droplets, passes toward the outlet of the cooling tower. 

2. Flow Through Eliminators: As the air passes through the drift eliminator’s intricate passageways, water droplets can’t follow the sharp turns due to inertia. 

3. Droplet Capture: These droplets impact the walls of the eliminator, get separated from the air, and form larger droplets. 

4. Drain Back: The collected water drains back into the fill basin or reservoir, reducing water wastage. 

Drift eliminators are engineered to offer low air resistance, ensuring minimal pressure drop while maintaining high droplet collection efficiency. 

Benefits of Drift Eliminators in Cooling Towers 

1. Water Conservation 

By minimizing unintended water losses, drift eliminators conserve thousands of liters per day in large facilities, lowering both water bills and environmental impact. 

2. Regulatory Compliance 

Drift eliminators help meet environmental regulations, such as those set by ASHRAE, OSHA, and EPA, especially concerning aerosol emissions and Legionella control. 

3. Protection of Nearby Equipment 

Water droplets escaping from cooling towers can settle on nearby equipment, causing rust or scaling. Drift eliminators mitigate this risk. 

4. Operational Efficiency 

Well-maintained drift eliminators contribute to the smooth and sustainable operation of the cooling tower, minimizing unplanned maintenance and downtimes. 

Where Are Drift Eliminators Used? 

Drift eliminators are installed in virtually every evaporative cooling tower, but they are especially critical in: 

• Power plants: Preventing electrical equipment corrosion 

• Chemical and petrochemical industries: Reducing toxic aerosol spread 

• Food and beverage plants: Maintaining hygienic surroundings 

• Urban buildings: Avoiding nuisance mist and overspray  

Innovations in Drift Eliminator Design 

 Some examples include: 

• Triple-pass designs 

• UV-stabilized materials 

• Modular and replaceable units 

• Hydrophobic coatings 

Some smart facilities are now integrating drift sensors to monitor drift emissions in real-time, ensuring instant detection of performance drops. 

Conclusion 

Drift eliminators may seem like small components, but their impact on water conservation, operational safety, and environmental compliance is significant. By effectively capturing and returning water droplets to the system, they not only reduce water loss but also protect equipment, improve air quality, and ensure regulatory standards are met. Whether in a power plant, refinery, or commercial building, installing high-efficiency drift eliminators is a smart investment toward sustainable and efficient cooling tower operation.