The key purpose of drift eliminators in evaporative cooling systems is to reduce (not eliminate as the name suggests) the escape of water droplets entrained in the discharge air stream of a cooling tower or evaporative condenser. This article discusses what drift eliminators are, why we need them.

What is a Drift Eliminator?

A drift eliminator can be defined as equipment containing a complex system of baffles designed to minimise drift discharging from a cooling tower or evaporative condenser. Today they are predominantly manufactured using either PVC or polypropylene (PP) material although some towers may still have metal type versions.

They are located on the discharge side of a cooling tower, either above the cooling tower heat transfer surface and distribution layer on a counterflow cooling tower or horizontally, in front of the heat transfer surface on a crossflow tower.

Why do we need Drift Eliminators?

Although the purpose of a drift eliminator is to reduce the escape of water droplets entrained in the air discharge, it is necessary to understand why this is important.

Their foremost purpose is to protect people and the local environment from escaping aerosols and water droplets from a cooling tower or evaporative condenser but this is not the only benefit of drift eliminators.

In the most serious case, if the water treatment regime has failed, then the drift eliminator provides the last line of defence in preventing the dispersion of harmful legionella bacteria often found in water cooling systems. Legionaires disease can be contracted by inhaling legionella bacteria contained in the aerosol discharge from the cooling tower.

By returning water droplets to the cooling tower, the drift eliminators aid in the conservation of water in the cooling system and the efficiency of a drift eliminator has a significant part to play in the water savings possible therefore it’s important to understand what the quoted efficiency refers to and the relative impact this has on water savings.