Legionella

Legionella is an air-borne bacteria that can affect those working in close proximity with Cooling Towers, Evaporative Condensers, and Fluid Coolers, as well as those inside closed office buildings.

Cooling towers, evaporative condensers and fluid coolers use a fan to move air through a recirculated water system. This allows a considerable amount of water vapor to be introduced into the surrounding area. This water may be in the ideal temperature range for Legionnaires’ disease bacteria growth, 68°-122°F. Legionella grows easily in the water, especially if algae and scale are present. Legionella can be dispersed with aerosolized drift or with the evaporate, but it may enter the air-conditioning system if there is a break between its ducts and those of the cooling tower or evaporative condenser.

Proper maintenance can prevent the spread of this bacteria.The cleaning of cooling towers should occur quarterly. Corroded parts, such as drift eliminators, should be replaced. Algae and accumulated scale should be removed. These measures will not only control the growth of bacteria, but will also maintain operating efficiency. During cleaning operations in confined spaces, safety procedures for entry into confined spaces should be applied.

Cooling water should be treated constantly. Ideally, an automatic water treatment system that continuously controls the quality of the circulating water should be used.

Fresh air intakes should not be built close to cooling towers since contaminated aerosols may enter the ventilation system. Air filters should be examined, cleaned and/or replaced periodically and tested for leaks. Cooling towers should be positioned so the drift or evaporate does not enter the fresh air intake.  The water system should be flushed out on a regular basis to prevent the water from stagnating.