© 2017 SPX Cooling Technologies, Inc. All Rights Reserved. July 8, 2019

Water Quality & Maintenance July 8, 2019 © 2017 SPX Cooling Technologies, Inc. All Rights Reserved

Water Quality - Overview Water quality is a very important factor in determining the life and ongoing performance of a cooling tower Hire the right water treatment company Do they have a track record on successful, long term installations? Make sure they regularly inspect your towers; go out and inspect the towers with them Monthly reports should not be the same Ensure passivation process completed properly on NEW galvanized tower start ups You should not see green growth, slime, excessive calcium build up, white rust, or solids in the water Monitor, correct, and hold accountable © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality - Maintenance Two main goals: 1. Protect health and safety by controlling biological growth in the circulating water 2. Protect materials in the process water system by maintaining water chemistry within acceptable limits Effective treatment has four basic components 1. Biocide to control microbial and bio-film growth 2. Inhibitors to protect against corrosion 3. Inhibitors to prevent scale precipitation 4. Solids separator © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality - Maintenance Cooling tower manufacturers typically not in water quality business, but we do publish ‘guidelines’ which can be used to help monitor the quality of your water Proper maintenance to resist: 1. Scale 2. Corrosion 3. Deposits 4. Biological Growth © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Scale Forms from dissolved minerals precipitating out onto system surfaces. As water evaporates, the concentration of dissolved solids becomes greater until the solubility of a particular scale-causing mineral salt is exceeded Examples: calcium carbonate, calcium sulfate, calcium phosphate, silica, magnesium silicate, iron oxide Mostly affected by temperature, pH, and high localized evaporation Prevention has three basic measures 1. Remove the water scaling ingredients from the water before use (i.e. softening, RO, etc) 2. Keep scale-forming ingredients in solution via scale inhibitor or acid such as phosphate or a specific polymer 3. Treatment process that alters crystal structure of the scale-forming material allowing them to settle rather than adhere to surfaces (which can then be removed by basin cleaning or sweeper system) © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Corrosion Several types of corrosion 1. General (total environment) 2. Pitting (localized) 3. Under deposit 4. Galvanic 5. Microbiologically induced (MIC) Corrosion is accelerated by high temperature, surface deposits, biological activity, high chlorides, etc; and is slightly different for galvanized steel and stainless steel © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Corrosion (Passivation Process) On new galvanized towers, it is critical a proper passivation process occurs to build a strong chemical barrier of zinc carbonate Zinc protects the base steel from corrosion by galvanic action. To prevent the zinc from corroding, a natural chemical barrier of zinc carbonate must be created The basic zinc carbonate barrier will from on galvanized surfaces within eight weeks of tower operation under these water conditions: Neutral pH (6.5-8.0), calcium hardness of 100-300 ppm (as CaCO3), and alkalinity of 100-300 ppm (as CaCo3) © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Corrosion (White Rust) White rust occurs when passivation is not completed as a white, waxy or fluffy adherent deposit on surfaces It is another form of zinc carbonate with a different porous structure than the protective ‘basic zinc carbonate barrier’ If untreated, the galvanized steel coating will continue to corrode leading to an early failure © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Deposits Deposit-forming solids can be introduced into the water from: Makeup water Process water Surrounding environment Increases fouling of fill and corrosion of metal surfaces Measures as Total Suspended Solids (TSS) Iron content can cause staining (with appearance of red rust) and contribute to deposit build up Treat with sweeper and filtration system or clean basins regularly © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Biological Growth Steps for continuous and effective biological control: 1. Eliminate nutrient sources that may add material to systems such as oil leaks, process leaks, etc. 2. Limit the ‘air-wash’ effect which naturally adds nutrients & bacteria to the system by removal of suspended solids and the bacteria that reside on them 3. Provide consistent and effective biocide treatment (chlorine, bromine, ozone, hydrogen peroxide) © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Biological Growth Legionella Pneumophila First discovered in 1976 in Philadelphia after outbreak at hotel One of more than 60 species of Legionella (only 18 other species cause infections and rarely are cause of community outbreaks) Commonly found where there is stagnant water – cooling tower CW basins, water heaters, shower fittings, etc. Thrives in temperatures 68F – 120F and tends to exist in biofilm/sludge layers Legionnaires’ Disease is a lung infection resulting from inhaling airborne water droplets/mist containing viable Legionella Pneumophila Needs to be small enough to pass deep into the lungs Most reported cases are in the 40-70 year age group Smokers, people with weak immune systems or acute respiratory illnesses are at an increased risk Source: Griswold Water Systems: Managing Legionella Bacteria in Cooling Towers: Your Water Management Plan © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Water Quality – Biological Growth Legionella Prevention & Control Maintain a strong and sound water treatment program Keep the basin and fill clean (biofilm = breeding ground for legionella) Drift eliminator effectiveness Refer to CTI and ASHRAE for further guidelines ASHRAE Standard 188 (2015) – Legionellosis: Risk Management for Building Water Systems ASHRAE Guideline 12 (2000) – Minimizing the Risk of Legionellosis associated with Building Water Systems (free download, note this document is in revision process at ASHRAE) CTI WTP-148 (2008) Guideline: Best Practices for Control of Legionella © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

Conclusions Cooling towers are nothing more than water – air heat exchangers which take advantage of the power of latent (evaporative) heat transfer There are several different ways to classify cooling towers: FEP vs. FAP, Open vs. Closed, Induced Draft vs. Forced Draft, Crossflow vs. Counterflow The process being served determined the heat load, the cooling tower determined the approach (CW – WB) Take advantage of the fan affinity laws to save energy: fan HP varies w/ the cube of the speed ratio Water quality is critical: control scale, corrosion, solids, and bio growth for best tower performance © 2017 SPX Cooling Technologies, Inc. All Rights Reserved July 8, 2019

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