7 Important Checks That Will Ensure Your Drift Eliminators Are Effective
What are drift eliminators?
Drift eliminators reduce the escape of water droplets entrained in the discharge airstream of the cooling tower. ACOP L8 & HSG 274 Pt2 require all evaporative cooling towers to be fitted with effective drift eliminators that minimise the escape of water droplets.
Drift should not be confused with plume. Plume from cooling towers is the dense white cloud that is most often visible in cooler weather caused by the condensation of evaporated water from the cooling tower. Plume is not considered to be hazardous because it is evaporated water and not droplets that are directly part of the circulating water.
Why are drift eliminators important?
Effective drift eliminators are vital in helping to combat legionella they are the last line of defence should legionella bacteria be present in the cooling system. Legionella can only be contracted by the inhalation of small water droplets containing the bacteria and therefore minimising their escape from the cooling tower reduces this risk.
Excessive drift loss may cause corrosion to the cooling tower casing, fans and other metal parts near the cooling tower.
During the winter months, excessive drift may cause ice to form on nearby roads and walkways.
Ineffective drift eliminators permit the escape of chemicals into the atmosphere.
How do I check that my cooling tower drift eliminators are effective?
Visible Droplets– This is the most basic of checks. If it is possible to see droplets escaping from the cooling tower you can be sure that the cooling tower has unacceptable levels of drift. The original ACOP L8 stated that “there shall be no visible drift”.
Fouling –to function correctly and maintain the hygienic operation of the cooling tower it is important to ensure that the eliminator modules are not scaled, fouled and are generally clean.
Visible gaps in the drift eliminator bank –Gaps either between the individual drift eliminator blades or between modules will permit the unnecessary escape of water droplets. It is important to ensure that sealing T’s are fitted between each module.
Damage to the Drift eliminator modules or frames –If the drift eliminator blades are damaged then they must be replaced as this will reduce the effectiveness of the drift eliminators. Damage to the frames ( if fitted) will effect the sealing of one module to another permitting the escape of water droplets.
Brittleness –This is usually caused be UV light degradation of the plastic. As parts of the eliminator module disintegrate it becomes less efficient resulting in increased drift.
- Modules that are fitting too tightly – whilst a close fit without gaps is important too tight a fit may result in the modules being damaged when removed from the tower or in extreme cases prevent them from being removed at all.
Test using sensitised papers –this provides clear evidence of the effectiveness of the drift eliminator bank. By comparing the results with results obtained from a high efficiency eliminator of known performance a qualitative assessment can be made of the performance of the eliminators fitted to your cooling tower. Please contact us for further details of drift eliminator testing.
Vistech offer a comprehensive drift inspection and testing service providing cooling tower operators with the evidence and confidence that their cooling towers are operating to the highest standards.
If you would like one of our engineers to survey your cooling tower and drift eliminators please contact us.
Lucy keeps the well oiled machine of Vistech Cooling running smoothly. She has close to a decade of experience working in the industry and creates industry-leading content that provides necessary information but also deeper insights into the field most people may not have considered.