Cooling towers are among the most energy efficient devices available on the market for extracting and rejecting heat in HVAC systems. However, as with any equipment that involves the storage of water, there are inevitable Legionella risks associated with cooling towers and, if not properly maintained, the consequences can be catastrophic. Safe maintenance processes are time consuming and expensive, but an imperative practise. Is it possible to streamline engineering time and cost whilst minimising the risk of bacterial growth?
Cooling towers utilise a simple process: By delivering a moving air stream within the unit, a portion of the stored water can be evaporated, providing significant cooling to the water system. Typically 75-80% of heat rejection is achieved through evaporation and any remainder is simply removed by the large volume of air passing over it. With such a large volume of stored water, it’s vital that cooling tower systems are maintained adequately. This not only ensures the unit delivers requisite heat transfer at maximum efficiency, but helps to prevent the proliferation of bacteria, which can lead to an increased risk of Legionnaires’ disease.
A cooling tower environment, with its warmth and large volume of dissolved airborne particulates and debris makes it the ideal environment for the growth of micro-organisms. In addition, cooling towers routinely remove large quantities of dirt, dust, pollen, bacteria, stack emissions and other airborne matter from the surrounding air during daily operation. Unless appropriate treatment measures are put into place, these contaminants can cause significant water-borne issues.
Legionella bacteria
Existing maintenance schemes generally involve the use of treatment chemicals and biocides in order to inhibit bacteria and algae growth. Not only is this costly, but time consuming too and for many building managers, engineering time has become a valuable commodity on site as a consequence of workforce streamlining, contract cutbacks and increasing client-side ‘value-for-money’ expectations.
With this in mind, the solution is simple: Prevent airborne debris and microbiological contaminants from being drawn into the system at the source using air filtration.
Introduced to the UK market in 2012, air intake screens are long lasting, purpose-designed filter mesh screens which can be affixed to the external air intakes on cooling towers, condensers, air handling units and chillers. With a lifespan of up to 15 years, air intake screens act as a cost effective protective component of any cooling tower treatment program and, by removing airborne particulates and debris from recirculating water, the potential for bacterial deposits is significantly reduced. This helps keep cooling systems operating at maximum design efficiency, enabling them to achieve their specified heat rejection capability and reducing strain placed upon the unit. More importantly, this means that the serviceable life of the plant is extended and the likelihood of mechanical downtime is significantly reduced.
An air intake screen prevents airborne debris before it can enter your cooling tower.
An air intake screen can also assist in the preventing microbiological bacteria and its food supply from entering the cooling tower’s stored water. By stopping insects, leaves and associated biological matter from being drawn into the system through the use of a filtered mesh, air intake screens also contribute towards a significant reduction in the potential for microbiological growth. In turn, this helps to reduce biocide costs which can be an excellent means of cost reduction on site.
Unscheduled maintenance and unit downtime can also be extremely costly to any facility. Maintaining clean, recirculating water is not only sound preventive maintenance, it also reduces heat exchanger and tower cleaning costs. Rather than waiting for airborne waste products to enter the system before cleaning it, air intake screens can be cleaned simply and efficiently using a soft brush, hose or vacuum. In cases of severe clogging, they can be easily removed for more thorough cleaning using a jet wash.
Air intake screens installed on BAC cooling tower
For more information on air intake screens, visit www.airintakescreens.co.uk or contact us on sales@ecex.co.uk.
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We’re itching to answer any questions you might have, so please do get in touch. You can contact us on sales@ecex.co.uk or by calling our sales office on 01635 244 100.
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