What causes Cooling Tower Drift?ĭrift can be defined as the water that is emitted along with the exhaust air of a cooling tower. Legionaires disease can be contracted by inhaling legionella bacteria contained in the aerosol discharge from the cooling tower.īy 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. 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. 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. Why do we need Drift Eliminators?Īlthough 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. The droplets agglomerate and they rapidly gain sufficient size and mass to overcome the discharge airstream velocity and drain back into the cooling tower rather than escape in the discharge airstream. This causes water droplets entrained in the airstream to collect on the eliminator foil surfaces. The key function 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.Īs air travels through the drift eliminator its direction of travel is altered by the eliminator foil or blade design. This article discusses what drift eliminators are, why we need them, the various types, maintenance requirements and considerations when replacing. They are located on the discharge side of a cooling tower, either above the cooling tower heat transfer surface and distribution system on a counterflow cooling tower or vertically, in front of the heat transfer surface on a crossflow tower. UK legislation (HSG274 Part 1) states that… “Drift eliminators should be installed in all towers that have fans” therefore apart from low velocity, natural draught towers, drift eliminators are required across all cooling towers and evaporative condensers. Location of Drift Eliminators of different types of cooling systems Do all Cooling Towers have Drift Eliminators? Today they are predominantly manufactured using either PVC or polypropylene (PP) material although some towers may still have metal type versions. Categorised in: Articles Maintaining the highest levels of quality and maintenance in delivering the last line of defence in your cooling system What is a Drift Eliminator?Ī 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.
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