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Condenser Water, Cooling Towers and Legionnaires’ Disease

What is Legionnaires’ Disease?

Legionnaires’ disease is a caused by bacterium known as Legionella. The disease spreads when people inhale water droplets that contain the bacteria. The symptoms of infection involve a fever, chills, cough and muscle aches. According to the CDC, 1 in 10 people can die from the infection once exposed. The young and elderly are more susceptible to infection as well.

Does your facility have a Cooling Tower?

Cooling towers and others coolers use a large fan to move air through a recirculated water system. A considerable amount of evaporation occurs in these systems, which introduces droplets of water in the immediate area around the facility. Drift eliminators are designed to reduce the total amount of water droplets that occur, but it is not a 100% perfect system.

As a result of normal operation, Condenser Water Systems end up operating in the ideal temperature range for Legionnaires’ disease to grow (approximately 68°-122°). To prevent this, a comprehensive chemical treatment system along with Operator training is necessary to maintain proper maintenance, which will control Legionnaires’ Disease Bacteria (LDB) growth and make for the most efficient Condenser Water System operation.

What can be done to control Legionnaires’ growth?

To prevent the growth of Legionnaires’, the following treatments or controls must be in place:

  • Biocides – A proper treatment program involves the injection of microbiocides into the Condenser Water Systems. Microbiocides will kill any potential bacterial growth.
  • Temperature – Maintaining the sump temperatures as low as possible (~68°F) will assist in controlling the potential growth of Legionnaires’. Unfortunately, sump temperature control relies on a number of factors: Tower Design, Heat Load, Flow Rate, and ambient Dry and Wet Bulb Temperatures.
  • Frequency of Cleaning – Cooling Towers should be removed from service between 2-4 times per year and disinfected using proper treatment. Equipment should be inspected monthly to ensure growth is not occurring. A proper chemical treatment program typically involves weekly testing of Condenser Water.