Cooling Tower Cleaning
Cooling towers are subject to much of the same contaminants that are present in heat exchangers and condensers. Just like heat exchangers and condensers, cooling tower cleaning needs to occur on a regular basis to insure peak performance. Removing debris and mineral scaling that inhibit heat transfer and reduces overall efficiency of the cooling tower should be one of the main focuses of cleaning cooling towers, but degradation of performance is not the only reason to clean cooling towers. Cooling towers can be a breeding ground for the growth of legionella bacteria. Legionella is harmful to humans and cooling towers growing legionella bacteria will send the bacteria airborne and spread it to their neighbors. When cleaning cooling towers, killing legionella bacteria and/or preventing its growth needs to be one of the main goals of the maintenance program along with increasing efficiency of the unit.
Legionella in Cooling Towers:
Legionella is a bacteria that can cause mild respiratory illness that may not require treatment or serious symptoms similar to pneumonia. The resulting sickness from legionella bacteria is called legionaires’ disease. If legionaires’ disease is not treated promptly with antibiotics, in some cases the sickness can be deadly. The largest and the most common source of legionaires’ disease are cooling towers. Some reasons that cooling towers have lead to high incidents of legionaires’ disease is because of their widespread use in industrial and commercial settings, their use for industrial air conditioning and thus their subsequent concentration in highly populated areas, and the design of the cooling towers themselves lend to spreading the disease through the air. Additionally the water temperature range in cooling towers (68-122 degrees F) is ideal for legionella growth.
In order to combat the threat of legionella bacteria, proper steps need to be taken to kill the bacteria. The OSHA Technical manual discusses cooling tower maintenance in relation to legionella bacteria in depth in Section III Chapter 7 of the OSHA (OSHA Cooling Tower Maintenance and Cleaning Guidelines). Section five of the guide outlines how often the cooling tower 
should be cleaned:
“Frequency of Cleaning. Cooling towers should be cleaned and disinfected at least twice a year. Normally this maintenance will be performed before initial start-up at the beginning of the cooling season and after shut-down in the fall. Systems with heavy bio-fouling or high levels of Legionella may require additional cleaning. Any system that has been out of service for an extended period should be cleaned and disinfected. New systems require cleaning and disinfecting because construction material residue can contribute to Legionella growth.”
The OSHA Manual also goes into detail on recommended cooling tower cleaning procedures including the use of biocides like chlorine and bromine to kill the legionella bacteria.
The Cooling Tower Cleaning Process:
Projectile Tube Cleaning’s cooling tower cleaning services follow the OSHA guidelines for removing legionella as well as focuses on cleaning to increase the cooling tower’s efficiency.
The cooling towers are disinfected with a biocide before the cleaning crew starts. While onsite the cooling tower cleaning crew washes all hard surfaces with high pressure water including the cooling tower hot deck and the sump floor. The plastic cooling tower fill is sprayed with a descaling agent that dissolves any mineral scaling. The descaler sits on the cooling tower fill for about a half hour to provide time for the scale to dissolve. After the waiting period, the descaler is washed off with a special nozzle that forcefully sprays the cooling tower fill without damaging it. The sump of the cooling tower is cleaned out by pressure washing, vacuuming, or a combination of the two processes depending on the amount of debris present in the tower. Once cleaning is completed, another treatment of biocide is used in order to help kill any bacteria that were liberated during cleaning. Projectile Tube Cleaning provides all labor and equipment to complete a turnkey cooling tower cleaning project.
Before Cleaning Cooling Tower Fill
After Cleaning Cooling Tower Fill
