Brady Blog- Trends and Talk

​Understanding And Preventing Legionnaires’ Disease

Thursday, March 23, 2017

Understanding And Preventing Legionnaires’ Disease

The Legionella bacteria was named after an outbreak in 1976 at the American Legion Convention that lead to 221 cases of illness and 34 deaths. The legionella bacteria can cause the serious respiratory disease, Legionellosis, or what is commonly referred to as, Legionnaires’ disease. As a facility owner, it’s important to recognize that cooling towers are susceptible to harboring and spreading the bacteria. Regular testing and proper treatment for Legionella can help protect your facility and surrounding area.

Knowing The Risk Legionella is a waterborne bacterium that can live and grow in all surface water, including ground water and wastewater. The bacteria thrive in the presence of a biofilm (slime) and can live inside amoebas, protozoan, and other microbiological organisms in the fouled water. Water between 75°Fand 115°F is the ideal environment for the Legionella bacteria, making cooling towers one of the main distribution methods of the bacteria. Hot tubs, decorative fountains, large plumbing systems, and hot water tanks and heaters are also prone to spreading the bacteria.

Spreading Legionella Legionella can only be contracted by inhaling contaminated mist or water droplets. It cannot be transmitted person to person. Cooling towers produce small water droplets that are propelled outside of the tower by thefan, making them a common source for spreading the bacteria.

Who’s At Risk? The majority of generally healthy people do not get sick after exposure to the Legionella bacteria. People with weakened immune systems, chronic lung disease, current or former smokers, and people over 50 are most vulnerable to the disease.

Preventing And Controlling The Bacteria The first line of defense against Legionella is a water treatment program that uses a dual alternating biocide program. One biocide needs to be an oxidizing biocide, like stabilized bromine, and the other needs to be a non-oxidizing biocide with or without a dispersant. The two chemicals work together to increase the effectiveness of your water treatment program, and can destroy and control the microbiological growth that canharbor the potentially dangerous bacteria.

When To Test There is currently no legislation mandating Legionella testing or the frequency but, there are recommendations based upon the facility type. Industrial sites should be tested at least twice a year, while office buildings should be tested quarterly. Schools, hospitals, and other locations where people are at a high risk of contracting the bacteria should be tested monthly.

If your facility receives a positive result after testing for Legionella, a water treatment technician will review the results and determine if system disinfection is necessary.

To learn more about Brady’s water treatment program and how it can help protect your facility fromLegionella, visit or call (800) 849-1915.


Protecting And Preventing White Rust In Galvanized Cooling Towers

Wednesday, March 08, 2017

Protecting And Preventing White Rust In Galvanized Cooling Towers

Changes in the galvanizing process and water treatment chemistry have led to an increase in white rust in cooling towers and evaporative condensers. White rust, once it has formed can reduce the lifespan of a cooling tower from approximately 15-20 years to as little as 3 - 5 years if left untreated.

Understanding White RustWhen looking at a galvanized piece of steel, have you noticed white deposits on the surface? White rust is a white deposit that forms on wet galvanized steel surfaces, and the white deposit is the loss of zinc in the galvanized coating on the steel. As the zinc is lost on the surface, the base metal underneath is left vulnerable to corrosion. Once white rust has formed, it can be challenging to control, which is why protecting equipment is key in preventing irreversible damage to a cooling tower.

Protecting With PassivationManufacturers of galvanized cooling towers recognize the risks of corrosion and white rust and defend the steel by applying a protective coating containing zinc. The zinc bonds to the steel underneath, forming a sacrificial layer. If the water in the basin has a pH out of range and contacts steel that has not been passivated, the water will begin to strip away the sacrificial layer through oxidation, exposing the base metal, and leaving it open to corrosion.

Passivation process could take up to 12 – 14 weeks where the zinc coating is converting into a more stable form of zincthat can better withstand long-term exposure to various conditions in a cooling tower. The process uses specialized chemical additions and strict pH control to maintain specific water chemistry conditions. Passivation should be completed before a new tower has a heat load added. If the tower is already online it can still be passivated, but can be more difficult to accomplish successfully, and may require specific chemical additions to control the water’s pH and other parameters.

When white rust has formed on a cooling tower, the water treatment plan will pivot from prevention to control. During tower cleanups, the technician can scrape and brush away the rust, and coatings and paint can be applied. However, the inability to reach every piece of metal inside the equipment can make it difficult to successfully repair, and white rust can continue to develop.

What’s At Risk?  Galvanized metal in a cooling tower that is exposed to water must be passivated to prevent white rust. Even towers made from stainless steel,fiberglass, and plastic can contain pieces of hardware that are galvanized steel, leaving the tower susceptible to white rust.

Prevention is crucial in preventing white rust, so if you are planning to purchase a new galvanized cooling tower or concerned about an existing cooling tower, visit