Cooling tower, closed-loop, and hybrid cooling providers integrated with water treatment programs.

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    Matched providers: 40

    Top countries: United Kingdom, United States

    Popular technologies: Coagulants and flocculants, Acid Dosing Systems

    Industrial Cooling System Design: Cooling Tower Selection, Water Chemistry, and Legionella Control

    Industrial cooling systems reject process heat via evaporative cooling towers (wet, dry, or hybrid), direct-contact condensers, or closed-loop fluid coolers. Evaporative cooling towers achieve wet bulb approach temperatures of 3 to 5 degrees C (cooling to within 3 to 5 degrees C of the ambient wet bulb temperature) and are the most efficient heat rejection method at 0.5 to 0.6 kWh of fan and pump energy per kWh of heat rejected.

    Cooling tower sizing parameters: range (temperature difference between hot inlet and cold outlet, typically 5 to 12 degrees C), approach (difference between outlet temperature and wet bulb), and L over G ratio (liquid to gas flow ratio, typically 0.75 to 1.5). Tower fill selection (film fill vs splash fill) depends on water quality: splash fill for silty or biofouling-prone water, film fill for clean water with lower approach temperatures.

    Cooling water chemistry control prevents scale (calcium carbonate, calcium sulphate, silica), corrosion (carbon steel, copper alloys, galvanised steel), and biological growth. Cycles of concentration (COC) determine blowdown rate: COC of 4 to 6 minimises make-up water consumption. Langelier Saturation Index (LSI) maintained between -0.5 and +0.5 prevents both corrosion and scale.

    Chemical treatment programmes typically include: corrosion inhibitor (azole for copper protection, molybdate or phosphonate for steel), scale inhibitor (polyacrylate or phosphonate anti-scalant dosed at 5 to 20 mg per L), biocide (oxidising biocide: sodium hypochlorite at 0.5 to 1.0 mg per L free chlorine continuous, or non-oxidising biocide: isothiazolone, DBNPA at quarterly shock dose 25 to 50 mg per L).

    Legionella pneumophila control in cooling towers is a legal obligation in the UK under HSE ACOP L8 and HSG274 Part 1: towers must be registered with local authority (under Notifiable Cooling Towers regulations 1992), risk assessment conducted by a competent person, and monthly Legionella culture samples with action limit of 1,000 CFU per L (trigger for immediate corrective action) and target below 100 CFU per L. HSE reports approximately 200 to 500 UK Legionnaires' disease cases annually, with cooling towers implicated in 20 to 30 percent of community-acquired outbreaks. US ASHRAE 188 (2018) provides risk management programme requirements for building water systems including cooling towers.

    Frequently Asked Questions

    What is cycles of concentration in a cooling tower and why does it matter?

    Cycles of concentration (COC, also called concentration ratio) is the ratio of dissolved solids in the circulating cooling water to dissolved solids in the make-up water supply. If make-up water conductivity is 500 microS per cm and circulating water is 2,500 microS per cm, COC equals 5. Running at higher COC reduces make-up water consumption (make-up rate equals evaporation rate divided by (COC minus 1)) but increases scaling and corrosion risk. At COC 6, 80 percent of make-up is retained versus lost at COC 1; at COC 3, only 67 percent is retained. Maximum achievable COC is limited by the scaling tendency of the worst scaling salt (usually CaCO3 or silica). Anti-scalant dosing typically allows COC 4 to 6 versus COC 2 to 3 without treatment. Each additional COC saves approximately 25 percent of blowdown water, directly reducing sewer disposal costs.

    What is Legionella and how is it controlled in cooling towers?

    Legionella pneumophila is a waterborne bacterium causing Legionnaires' disease (severe pneumonia) when aerosolised water droplets are inhaled. Cooling towers are high-risk because they generate fine aerosol, maintain water at 20 to 45 degrees C (optimal growth range), and can accumulate biofilm, scale, and sediment (providing nutrient and protective environments). UK HSE ACOP L8 requires: monthly Legionella culture samples (action limit 1,000 CFU per L requires immediate corrective action), free chlorine maintained at 0.5 to 1.0 mg per L continuous, annual clean-and-disinfect (biocide shock at 5 mg per L free chlorine for 1 hour or equivalent), and drift eliminators to below 0.002 percent of recirculating water flow. Tower should be decommissioned and clean-disinfected before any extended shutdown.

    How much water does an evaporative cooling tower use?

    Water consumption of a cooling tower has three components: (1) Evaporation (dominant): approximately 1.8 L per kWh of heat rejected at typical summer conditions (0.5 percent of circulating water flow per degree C of range); (2) Blowdown: evaporation rate divided by (COC minus 1); at COC 4, blowdown equals evaporation divided by 3; (3) Drift: aerosol carryover, typically 0.0005 to 0.002 percent of circulating flow with modern drift eliminators. Total make-up equals evaporation plus blowdown plus drift. For a 1,000 kW process cooling duty at COC 5 and 35 degrees C ambient wet bulb: evaporation approximately 1,800 L per hr, blowdown 450 L per hr, drift 5 to 20 L per hr, total make-up 2,255 to 2,270 L per hr. Water efficiency improvements: increase COC (with water treatment), install drift eliminators, and implement rain water harvesting for cooling tower make-up.

    What is the difference between an open and closed cooling system?

    An open (evaporative) cooling system circulates water through a cooling tower where a portion evaporates to atmosphere, removing latent heat. It achieves low approach temperatures (3 to 5 degrees C to wet bulb) and high efficiency but requires significant make-up water, water treatment, and Legionella management. A closed cooling system circulates glycol or water through an air-cooled heat exchanger (dry cooler or fluid cooler) where heat is rejected to air by sensible cooling only, with no evaporation and no water loss. Closed systems require no water treatment and have no Legionella risk, but approach temperature is limited to ambient dry bulb plus 5 to 10 degrees C, meaning higher process cooling temperatures in summer and higher chiller energy consumption. Hybrid systems combine dry cooling with adiabatic cooling (evaporative pre-cooling of air) to achieve intermediate water consumption (50 to 70 percent reduction vs fully evaporative) with near-wet-bulb performance.

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    Industrial Cooling System Companies

    Cooling tower, closed-loop, and hybrid cooling providers integrated with water treatment programs.

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    Specialists in industrial cooling system

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    Shandong Dongrun Instrument Science and Technology Co.,Ltd

    Verified

    China · 51-200 employees

    Founded in 1998 and headquartered in Yantai, Shandong, China, Shandong Dongrun Instrument Technology Co., Ltd. is a premium high-tech enterprise focusing on advanced measurement products and digital solutions. It features a 13,000squaremetre production site and dedicated professional R&D platforms. Dongrun holds the certifications of National HighTech Enterprise and national-level "Specialized, Sophisticated, Distinctive and Innovative Little Giant" enterprise. We are also recognized as a Shandong Provincial Gazelle Enterprise, running a Provincial Enterprise Technology Center and a Provincial Engineering Research Center. Backed by strong innovation capabilities, we own more than 100 intellectual property rights, including 16 invention patents. Dongrun specializes in the R&D, manufacturing, and sales of water quality monitoring sensors, online analyzers, and level-measuring instruments. Beyond hardware manufacturing, we deliver full-range IoT software development, system integration, and engineering services. Our products are exported to over 70 countries worldwide, serving diverse industries such as petroleum, petrochemical, coal chemical, pharmaceutical, water utilities, hydrology, marine monitoring and aquaculture. Upholding the principles of precision, innovation, and global customer-oriented support, Dongrun provides dependable, intelligent measurement solutions to address the evolving demands of industries across the globe.

    Preventive Maintenance ServicesEmergency Repair and TroubleshootingRemote Monitoring & Support Services

    Related providers

    Listed for overlapping capabilities, not for industrial cooling system specifically.

    Sidonwater S.L.

    Verified

    Spain · 1-50 employees · 5 case studies · 3 datasheets

    Sidon Water is a water technology company specialised in non-chemical water treatment and system optimisation. We develop and deploy advanced solutions that prevent and remove limescale, reduce fouling and corrosion, and improve the performance of cooling towers, industrial water systems, and reverse osmosis and desalination installations. Sidon Water works with industrial clients, commercial building owners, OEMs and EPC partners to deliver measurable improvements in energy efficiency, operational reliability and asset lifetime. Our activities cover the full cycle from analysis and pilot projects to system integration, commissioning and long-term performance optimisation.

    Electrochemical TechnologiesProcess Water TreatmentWastewater Treatment

    PNR ITALIA Srl

    Verified

    Italy · 51-200 employees · 19 case studies

    We produce a comprehensive range of spraying solutions, encompassing everything from small-scale nozzles to large industrial spraying systems. Our diverse product line includes various types of nozzles tailored to meet the specific requirements of every application and customer need. The company was established in Milan in November 1968, focusing on distributing parts and components for fire protection systems. Over time, we expanded our offerings to include a diverse range of industrial sprayers tailored to various applications. In addition to our distribution and manufacturing of fire protection system components and industrial sprayers, we specialize in designing and producing pneumatic spray nozzles for industrial use and tank washing nozzles. Our product line also encompasses a variety of complementary accessories essential for industrial washing, including filters, spray guns, and hoses. Furthermore, we offer ejectors, blower nozzles, swivel joints, and hose clamps to provide comprehensive solutions for our customers' needs. PNR Italia is part of the Tecomec Group and oversees four other affiliated companies to form PNR Company, a consolidated reality with a significant presence on the market.

    Microfiltration (MF) SystemsDisinfection TechnologiesDisinfection Chemicals
    SL

    Shandong LoyalMem Tech Co., Ltd.

    Verified

    China · 51-200 employees

    Shandong LoyalMem Tech Co., Ltd. manufactures reverse osmosis (RO), ultrafiltration (UF), nanofiltration (NF) and membrane bioreactor (MBR) membrane products, along with electrodeionization (EDI) modules, for industrial and municipal water-treatment applications. LoyalMem supplies membrane elements and modules for water-treatment equipment manufacturers, engineering companies and project buyers.

    Reverse OsmosisUltrafiltrationNanofiltration

    Ecosystems International

    Verified

    Indonesia · 51-200 employees

    PT Ecosystems International (PT ESI) was established at Jakarta on 21st November 2006. We are an industrial effluent treatment systems integrator specializing in electrocoagulation (EC), a unique waste water treatment profile. PT ESI has capabilities in designing complete waste water treatment solutions by combining various effluent treatment systems such as the electro-coagulation, biological, chemical processes and membrane filtration, offering its customers a wide and comprehensive range of solutions, tailored to suit their various needs – ranging from basic effluent treatment for discharge to effluent recycling for water reuse. The Company is experienced in handling the design, engineering, procurement, construction and operation of new Effluent Treatment Plants (“ETP”) and possesses expertise in retrofitting existing ETP to increase the flow rate and treatment capability without any major infrastructure increase PT ESI is also a premier waste water treatment service company specializing in handling waste water generated from Exploration (Drilling) and Produced Water. Customers in Indonesia include major Oil & Gas companies such as Pertamina, Exxon, Chevron, Petro-China and Medco. Operations in Indonesia are provided by both mobile and fixed units. At drill sites where waste-water recycling is required, PT ESI supplement these treatment units with skid mounted mobile Reverse Osmosis systems. The technologies and solutions employed by PT ESI are developed in-house and examples of these are its proprietary Trident™ Electro Contaminant Removal (“ECR”) system, the Stage Contaminant Removal (“SCR”) process and Mobile On-Site Waste-Water Treatment (“OWT”) units

    Reverse Osmosis (RO) SystemsUltrafiltration (UF) SystemsMulti-media Filtration (MMF) Systems

    Devram International

    Verified

    India · 1-50 employees

    DEVRAM INTERNATIONAL, headquartered in Surat, India, is a pioneering enterprise specializing in Snow and Rainwater Management with advanced contamination reduction abilities for storage and artificial groundwater recharge. Established as the commercial wing of Shree Someshwar Education Trust (SSET), DEVRAM INTERNATIONAL is driven by a mission to provide tech-enabled, nature-based solutions that address the world’s most pressing water and climate challenges. The company’s work integrates Integrated Water Resources Management (IWRM) principles and contributes across the source-to-sea water management cycle, ensuring holistic restoration of the global water cycle. Its innovative portfolio includes rainwater harvesting systems, stormwater management, aquifer recharge, artificial glaciers, desert trenches, rooftop water filtration, and green infrastructure models. These interventions directly reduce salinity in soils and aquifers, restore ecological balance, and enhance resilience to droughts, floods, and climate change. As the commercial promoter of the Global Rainwater Management Program (GRMP), DEVRAM INTERNATIONAL advances the vision of GRMP as a Global Common Minimum Program (GCMP) for nations and international bodies. GRMP demonstrates how rainwater and snowwater retention can restore entire natural cycles, while delivering unmatched benefits across the Sustainable Development Goals (SDGs). Alignment with the SDGs • SDG 2 (Zero Hunger): By reducing soil salinity, supporting organic farming, and ensuring water availability for agriculture, GRMP safeguards food security. • SDG 6 (Clean Water & Sanitation): DEVRAM’s recharge structures and contamination reduction technologies guarantee safe, sustainable drinking water for communities. • SDG 7 (Affordable & Clean Energy): By reducing dependency on energy-intensive desalination, GRMP lowers national energy bills and improves hydropower capacity. • SDG 9 (Industry, Innovation & Infrastructure): DEVRAM integrates nature-based water infrastructure with industrial operations, reducing OPEX and water footprints. • SDG 11 (Sustainable Cities & Communities): Through stormwater management and aquifer recharge, GRMP mitigates urban flooding and secures municipal supplies. • SDG 12 (Responsible Consumption & Production): Promotes a circular water economy, reusing wastewater, biogas from organic waste, and aligning with industrial CSR. • SDG 13 (Climate Action): By lowering GHG emissions and cooling local climates through water cycle restoration, GRMP strengthens resilience to global warming. • SDG 14 (Life Below Water): Free-flowing rivers, improved aquaculture, and reduced dam-related aquatic pollution support marine and freshwater ecosystems. • SDG 15 (Life on Land): DEVRAM’s interventions restore wetlands, mangroves, peatlands, and biodiversity-rich ecosystems, addressing land degradation. • SDG 17 (Partnerships for the Goals): The company actively collaborates with UN agencies, governments, World Bank programs, and private investors to scale GRMP globally. Founders and Leadership Dhaval Pandya, Co-Founder of DEVRAM INTERNATIONAL and CEO of SSET, is a globally recognized sustainability leader. He co-developed the Global Rainwater Management Program (GRMP), recognized by the United Nations Global Water Partnership (GWP) and the Government of India. As a Technical Committee Member (WRD03) of the Bureau of Indian Standards (BIS), he contributes to national water policy frameworks. His work is featured in UNCCD IWRM Action Hub and global forums like COP, Stockholm World Water Week, and World Bank SDG reviews. Manalika Pandya, Co-Founder, plays a critical role in embedding social, gender, and educational dimensions into GRMP. Her focus on women empowerment, local capacity building, and community-driven adoption ensures the program’s sustainability at the grassroots. Impact and Recognition DEVRAM INTERNATIONAL has piloted groundbreaking projects such as: Kawas Village (Gujarat, India): A GRMP model village achieving self-reliance in water, organic farming, and biogas, while resolving conflicts with industries. Delhi’s Water Paradox (Figshare Study): Shows how GRMP can solve megacity water crises without costly desalination or dams. GSECL Surat Project: Demonstrates reduced industrial water costs through GRMP recharge planning, aligning profitability with SDG and ESG goals. These projects show GRMP’s potential to reduce industrial and municipal water supply costs by up 60%, avoid massive investments in desalination and dams, and enable nations to achieve water sovereignty. Core Competencies • Rainwater & Snowwater Harvesting • Artificial Groundwater Recharge & Salinity Reduction • Stormwater Management & Urban Flood Control • Transboundary Water Cooperation • IWRM & Source-to-Sea Water Governance • AI-Enabled Hydrological Modelling & Policy Analytics • Environmental Services Restoration (Wetlands, Mangroves, Peatlands) • Circular Economy.

    Activated Carbon FiltrationGranular Activated Carbon (GAC) FiltersMulti-media Filtration (MMF) Systems

    Brine Consulting

    Verified

    Netherlands · 1-50 employees

    BRINE CONSULTING delivers senior-level strategy, technical design, and actionable insight across the full lifecycle of water-related challenges. We support clients with advisory and due diligence, advanced brine management and resource recovery, industrial and municipal water reuse, and MLD/ZLD systems. Our team also leads ESG and climate-resilience strategy, innovation scouting, and international development and PPP advisory. With deep specialization in desalination, brine valorization, circular economy models, and high-impact infrastructure, we help organizations turn water and waste streams into opportunities, providing clear thinking, rapid delivery, and solutions built for real-world results.

    Activated Carbon FiltrationReverse Osmosis (RO) SystemsUltrafiltration (UF) Systems

    ByoSis

    Netherlands · 51-200 employees

    ByoSis is a producer of biological and physicochemical wastewater treatment plants. These industrial treatment plants are designed, manufactured, supplied, and maintained by ByoSis. Our clients are companies with wastewater streams that are too contaminated for discharge.

    FiltrationScreeningIon Exchange

    Genesis Water Technologies

    United States

    Genesis Water Technologies, headquartered in Maitland, Florida, designs modular water and wastewater treatment systems plus specialty media and flocculants for industrial clients. The firm addresses silica removal, cooling tower cycles of concentration, scale and corrosion control, and water recycling for data centers and manufacturers. Named offerings include the Zeoturb bio-organic flocculant, GCAT catalytic membrane protection, and Genclean cooling tower tablets, backed by engineering process optimization consulting.

    Modular treatment systemsProcess optimization consultingTreatment media supply
    AC

    Advanced Chemical Systems

    United States

    Advanced Chemical Systems, Inc. (ACS) is a water and wastewater treatment company headquartered in Franklin, Wisconsin. Founded in 1977, ACS provides custom chemical and equipment solutions for industrial wastewater treatment across a wide range of facilities and applications, including boilers, cooling towers, plating, parts washing, and machining processes. The company combines treatment chemistry with equipment, water sample analysis, compliance consulting, and staff training to help industrial sites meet discharge and process water quality requirements.

    Industrial wastewater treatment solutionsBoiler and cooling water treatmentWater sample analysis and monitoring

    Accepta

    United Kingdom

    Accepta is a UK-based manufacturer and supplier of speciality water treatment chemicals, dosage equipment, test kits and laboratory services. Their products protect water systems including boilers, cooling systems, HVAC, drinking water, reverse osmosis and wastewater applications across commercial and industrial markets.

    Water treatment chemical supplyLaboratory analysis (microbiology chemistry metals)Custom chemical manufacturing and toll blending

    Chardon Labs

    United States

    Chardon Labs is a commercial and industrial water treatment service provider headquartered at 7300 Tussing Road in Reynoldsburg, Ohio. Founded in 1965, the company delivers customized treatment programs for cooling towers, boilers, and closed-loop systems, addressing scale, corrosion, biological growth including Legionella, and mineral content. Services include water testing, chemical application, system cleaning and flushing, filtration, and Legionella testing and control. Chardon Labs is ISO 9001:2015 certified and offers ASSE 12080 Legionella certification, serving customers across roughly 13 states in the eastern and midwestern United States.

    Boiler water treatmentCooling tower water treatmentClosed-loop water treatment

    Ecosphere Technologies

    United States

    Ecosphere Technologies, operating as Brisben Water, develops patented technologies for industrial water treatment and wastewater recycling, with a focus on scale inhibition and corrosion control. The company uses advanced oxidation processes to recycle and reuse wastewater across oil and gas, mining, agriculture, and municipal sectors, and also addresses bacteria control and cooling and boiler water treatment. Headquartered in Hobe Sound, Florida, it has processed billions of gallons of wastewater in oil and gas operations.

    Scale and corrosion control for produced waterBacteria control in water systemsCooling and boiler water treatment

    DALI - Pipeline Monitoring

    Belgium · 1-50 employees

    DALI - Pipeline Monitoring specializes in advanced real-time leak and intrusion detection for pipelines using Distributed Acoustic Sensing (DAS) and fiber optic technology. Their solutions help utility companies and industrial facilities minimize Non-Revenue Water (NRW) losses, reduce waste, and prevent costly incidents, ensuring efficient pipeline management.

    Online/Real-Time MonitoringRemote Sensing and TelemetryIoT and Smart Monitoring

    Kurita America

    United States

    Kurita America provides industrial water treatment solutions including chemicals, equipment, engineering, and services. As part of the global Kurita Group, the company delivers customized approaches to address complex water management challenges across diverse industries while promoting sustainability.

    Water treatment chemical solutionsEquipment supply and installationEngineering and consulting services
    V

    VVater

    United States

    VVater is a next-generation water technology company headquartered in West Lake Hills, Texas, United States, focused on solving water scarcity through advanced purification and reuse. The company develops consumable-free treatment systems that purify water to ultrapure standards while using significantly less energy than conventional reverse osmosis, serving industrial, municipal, and recreational sectors. VVater specializes in circular water economies, supplying solutions for direct potable reuse, PFAS destruction, industrial process water, zero liquid discharge, and large-scale artificial aquatic facilities such as surf parks and artificial beaches.

    Direct potable reuse and water recycling systemsIndustrial water treatment for boiler, cooling, and process waterZero liquid discharge solutions
    C

    ChemTreat

    United States

    ChemTreat is one of the largest industrial water treatment companies in the United States, headquartered in Richmond, Virginia. It designs custom chemical treatment programs for boiler water, cooling water, pretreatment, wastewater and water reuse, combining field technical support, laboratory services and digital monitoring to improve efficiency and protect equipment across many industries.

    Boiler water treatmentCooling water treatmentPretreatment and filtration

    Chem-Aqua

    United States

    Chem-Aqua is an industrial water treatment company providing customized programs for boilers, cooling systems, and process water across more than 55 countries. The company designs bespoke treatment programs that aim to reduce water, energy, and maintenance costs while protecting system reliability and safety. Its work spans steam boiler and closed-loop treatment, cooling tower and chiller treatment, Legionella risk management, and microbiological and biofilm control. Chem-Aqua is the water treatment division of NCH Corporation, headquartered in Irving, Texas, and now operates as part of Solenis following acquisition. The company reports over 34,000 implemented programs and more than 1,600 water treatment team members worldwide.

    Steam boiler and closed-loop water treatmentCooling tower and chiller water treatmentLegionella risk management
    S

    Sorbster

    United States

    Sorbster specializes in industrial wastewater treatment, manufacturing adsorbent media to remove contaminants from water used in boilers, cooling towers, and other industrial applications. Its product range targets silica, selenium, mercury, copper, and multiple heavy metals, achieving removal rates up to 99 percent. Based in Cleveland, Ohio, the company supports customers with water diagnostics, pilot treatment programs, temporary treatment options, and pump-and-treat applications using standard industry tanks and cartridges.

    Water diagnostics and testingPilot treatment programsTemporary and emergency treatment options
    WO

    Watertech of America

    United States

    Watertech of America, Inc. is an industrial water treatment company founded in 1980 and headquartered in Greenfield, Wisconsin, United States. The firm combines total system management with chemical and equipment expertise to treat water and wastewater across industrial and commercial markets, serving customers in Wisconsin, Minnesota, Iowa, and northern Illinois. Its programs cover boiler water, cooling water, closed loop, and wastewater applications for clients in the energy, food and beverage, dairy, healthcare, commercial real estate, and manufacturing industries. Watertech also offers smart testing and analytics, including its Aquassist smartphone app that automates water testing, alongside hands free chemical delivery, water analysis, and consulting services focused on system efficiency and sustainability.

    Industrial water treatment consultingBoiler water treatment programsCooling water treatment programs
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    Buyer's guide

    The buyer's guide to industrial cooling system

    OverviewFAQScenarioQuestions to askCost driversRegulations

    Industrial Cooling System Design: Cooling Tower Selection, Water Chemistry, and Legionella Control

    Industrial cooling systems reject process heat via evaporative cooling towers (wet, dry, or hybrid), direct-contact condensers, or closed-loop fluid coolers. Evaporative cooling towers achieve wet bulb approach temperatures of 3 to 5 degrees C (cooling to within 3 to 5 degrees C of the ambient wet bulb temperature) and are the most efficient heat rejection method at 0.5 to 0.6 kWh of fan and pump energy per kWh of heat rejected.

    Cooling tower sizing parameters: range (temperature difference between hot inlet and cold outlet, typically 5 to 12 degrees C), approach (difference between outlet temperature and wet bulb), and L over G ratio (liquid to gas flow ratio, typically 0.75 to 1.5). Tower fill selection (film fill vs splash fill) depends on water quality: splash fill for silty or biofouling-prone water, film fill for clean water with lower approach temperatures.

    Cooling water chemistry control prevents scale (calcium carbonate, calcium sulphate, silica), corrosion (carbon steel, copper alloys, galvanised steel), and biological growth. Cycles of concentration (COC) determine blowdown rate: COC of 4 to 6 minimises make-up water consumption. Langelier Saturation Index (LSI) maintained between -0.5 and +0.5 prevents both corrosion and scale.

    Chemical treatment programmes typically include: corrosion inhibitor (azole for copper protection, molybdate or phosphonate for steel), scale inhibitor (polyacrylate or phosphonate anti-scalant dosed at 5 to 20 mg per L), biocide (oxidising biocide: sodium hypochlorite at 0.5 to 1.0 mg per L free chlorine continuous, or non-oxidising biocide: isothiazolone, DBNPA at quarterly shock dose 25 to 50 mg per L).

    Legionella pneumophila control in cooling towers is a legal obligation in the UK under HSE ACOP L8 and HSG274 Part 1: towers must be registered with local authority (under Notifiable Cooling Towers regulations 1992), risk assessment conducted by a competent person, and monthly Legionella culture samples with action limit of 1,000 CFU per L (trigger for immediate corrective action) and target below 100 CFU per L. HSE reports approximately 200 to 500 UK Legionnaires' disease cases annually, with cooling towers implicated in 20 to 30 percent of community-acquired outbreaks. US ASHRAE 188 (2018) provides risk management programme requirements for building water systems including cooling towers.

    Post your industrial cooling system project

    Frequently asked questions

    What is cycles of concentration in a cooling tower and why does it matter?

    Cycles of concentration (COC, also called concentration ratio) is the ratio of dissolved solids in the circulating cooling water to dissolved solids in the make-up water supply. If make-up water conductivity is 500 microS per cm and circulating water is 2,500 microS per cm, COC equals 5. Running at higher COC reduces make-up water consumption (make-up rate equals evaporation rate divided by (COC minus 1)) but increases scaling and corrosion risk. At COC 6, 80 percent of make-up is retained versus lost at COC 1; at COC 3, only 67 percent is retained. Maximum achievable COC is limited by the scaling tendency of the worst scaling salt (usually CaCO3 or silica). Anti-scalant dosing typically allows COC 4 to 6 versus COC 2 to 3 without treatment. Each additional COC saves approximately 25 percent of blowdown water, directly reducing sewer disposal costs.

    What is Legionella and how is it controlled in cooling towers?

    Legionella pneumophila is a waterborne bacterium causing Legionnaires' disease (severe pneumonia) when aerosolised water droplets are inhaled. Cooling towers are high-risk because they generate fine aerosol, maintain water at 20 to 45 degrees C (optimal growth range), and can accumulate biofilm, scale, and sediment (providing nutrient and protective environments). UK HSE ACOP L8 requires: monthly Legionella culture samples (action limit 1,000 CFU per L requires immediate corrective action), free chlorine maintained at 0.5 to 1.0 mg per L continuous, annual clean-and-disinfect (biocide shock at 5 mg per L free chlorine for 1 hour or equivalent), and drift eliminators to below 0.002 percent of recirculating water flow. Tower should be decommissioned and clean-disinfected before any extended shutdown.

    How much water does an evaporative cooling tower use?

    Water consumption of a cooling tower has three components: (1) Evaporation (dominant): approximately 1.8 L per kWh of heat rejected at typical summer conditions (0.5 percent of circulating water flow per degree C of range); (2) Blowdown: evaporation rate divided by (COC minus 1); at COC 4, blowdown equals evaporation divided by 3; (3) Drift: aerosol carryover, typically 0.0005 to 0.002 percent of circulating flow with modern drift eliminators. Total make-up equals evaporation plus blowdown plus drift. For a 1,000 kW process cooling duty at COC 5 and 35 degrees C ambient wet bulb: evaporation approximately 1,800 L per hr, blowdown 450 L per hr, drift 5 to 20 L per hr, total make-up 2,255 to 2,270 L per hr. Water efficiency improvements: increase COC (with water treatment), install drift eliminators, and implement rain water harvesting for cooling tower make-up.

    What is the difference between an open and closed cooling system?

    An open (evaporative) cooling system circulates water through a cooling tower where a portion evaporates to atmosphere, removing latent heat. It achieves low approach temperatures (3 to 5 degrees C to wet bulb) and high efficiency but requires significant make-up water, water treatment, and Legionella management. A closed cooling system circulates glycol or water through an air-cooled heat exchanger (dry cooler or fluid cooler) where heat is rejected to air by sensible cooling only, with no evaporation and no water loss. Closed systems require no water treatment and have no Legionella risk, but approach temperature is limited to ambient dry bulb plus 5 to 10 degrees C, meaning higher process cooling temperatures in summer and higher chiller energy consumption. Hybrid systems combine dry cooling with adiabatic cooling (evaporative pre-cooling of air) to achieve intermediate water consumption (50 to 70 percent reduction vs fully evaporative) with near-wet-bulb performance.

    Illustrative scenario · Food and beverage manufacturing

    A composite drawn from typical projects in this category, not a single client engagement. Figures are indicative.

    Challenge
    A large food processing site in the North West of England operated a 4,000 kW evaporative cooling system running at COC 2 to 3 due to hard make-up water causing chronic CaCO3 scale. Water consumption was 8,000 m3 per month and three Legionella action limit exceedances had occurred in 12 months, triggering HSE correspondence.
    Approach
    Installed a water softener (duplex cation exchange, treating 100 percent of make-up water to below 5 mg per L hardness) enabling COC to increase to 6 without scaling risk. Replaced the Legionella risk management contractor, introduced weekly biocide shock dosing with DBNPA, installed continuous chlorine monitoring, and implemented an electronic logbook aligned with HSG274 Part 1. Drift eliminators were replaced on all three towers.
    Outcome
    Make-up water consumption reduced from 8,000 to 4,200 m3 per month (47 percent reduction), saving 45,000 GBP per year in water and sewer charges. Legionella culture results remained below 100 CFU per L for 18 consecutive months after the programme. Blowdown volume reduction also reduced sewer trade effluent volume, cutting consent charges by a further 8,000 GBP per year.

    Questions to ask shortlisted providers

    5
    1. 01

      What cycles of concentration does your proposed water treatment programme support, and what is the expected annual water savings versus our current COC?

      Each additional COC reduces make-up water consumption significantly and directly reduces water and sewer charges. A proposal that maintains COC 3 versus one achieving COC 6 can represent a 40 percent difference in water consumption. Ask for a water balance calculation showing predicted make-up, blowdown, evaporation, and drift at the proposed COC.

    2. 02

      How will the Legionella management programme comply with HSG274 Part 1, and what are the monthly sample turnaround times and action limit response procedures?

      HSE ACOP L8 requires monthly Legionella culture samples with an action limit of 1,000 CFU per L triggering immediate corrective action. The speed of culture result turnaround (typically 10 to 14 days for standard culture) and the action plan for levels between 100 and 1,000 CFU per L are critical. Ask to see the written scheme and confirm that the contractor holds appropriate qualifications (Legionella Control Association registration or equivalent).

    3. 03

      What inhibitor chemistry are you proposing and is it approved for use in a food production environment where aerosols may reach the production area?

      Cooling tower biocides and corrosion inhibitors (azoles, phosphonates, isothiazolones) must be approved under the Biocidal Products Regulation (BPR) PT2 for cooling water. In a food facility, aerosol drift from cooling towers landing on intake air handling units can carry chemical residues into the production area. Confirm the chemistry is food-grade compatible and that drift eliminators meet standard EN 13741.

    4. 04

      What is the expected corrosion rate on our carbon steel heat exchangers at the proposed treatment chemistry, and how will you monitor this?

      Corrosion inhibitor programmes are validated by corrosion coupon monitoring (coupons installed in the cooling water circuit, removed and weighed after 30 to 90 days). Target carbon steel corrosion rates: below 2 mils per year (mpy) at optimised chemistry. Without monitoring, corrosion is undetected until heat exchanger failure or pitting is found during planned inspection.

    5. 05

      What is the make-up water quality test frequency and how quickly will the programme respond to seasonal water quality changes?

      UK mains water hardness and chemistry varies seasonally (particularly in areas using a blend of groundwater and surface water). A cooling water programme optimised for summer water quality may over- or under-dose inhibitors in winter, causing scaling or corrosion. Confirm that make-up water is tested monthly and that the treatment doses are adjusted based on incoming water analysis.

    What drives cost in this category

    4
    Make-up water and sewer charges
    Water consumption is the dominant operating cost for an evaporative cooling system. At COC 3, make-up equals 1.5 times evaporation; at COC 6, make-up equals 1.2 times evaporation. For a 1,000 kW system evaporating 1,800 L per hr, the difference between COC 3 and COC 6 is 600 L per hr (5,256 m3 per year). At UK water and sewer rates averaging 5 to 8 GBP per m3, this represents 26,000 to 42,000 GBP per year in direct savings from improving COC.
    Water treatment chemical programme
    Annual chemical cost for a 1,000 kW cooling system at COC 5 runs 5,000 to 20,000 GBP per year depending on make-up water hardness, system metallurgy, and biocide programme intensity. Bleed conductivity controllers and automated dosing pumps (capital 2,000 to 8,000 GBP) pay back within 1 to 2 years by eliminating manual dosing error and optimising inhibitor consumption.
    Legionella compliance and monitoring
    Monthly Legionella culture sampling (4 to 8 samples per site per month), written scheme preparation, and Legionella risk assessment typically cost 5,000 to 15,000 GBP per year for a 3-tower site. An action limit exceedance (above 1,000 CFU per L) triggers hyperchlorination, emergency sampling, and potential HSE reporting costs of 5,000 to 20,000 GBP per incident. The cost of a confirmed Legionnaires' disease outbreak with litigation exposure is orders of magnitude higher.
    Energy and scale cleaning
    Scale on heat exchanger surfaces acts as insulation: a 1 mm CaCO3 scale layer increases heat exchanger fouling resistance by approximately 10 percent, requiring chiller head pressure to rise to compensate, increasing compressor energy by 5 to 10 percent. Acid descaling of a scaled cooling system (decommission, chemical clean, recommission) costs 5,000 to 30,000 GBP per event. Proper scale inhibition eliminates this cost.

    Key regulations and standards

    4
    HSE ACOP L8: Legionella Control in Cooling Towers
    The Health and Safety Executive's Approved Code of Practice L8 (Legionnaires' disease: the control of Legionella bacteria in water systems) is the primary UK regulatory document for cooling tower Legionella management. It requires: written risk assessment by a competent person, a written control scheme, monitoring (monthly Legionella culture, continuous residual biocide monitoring), records kept for at least 5 years, and nominated responsible person accountable for the programme. Failure to implement ACOP L8 requirements is an absolute defence in HSE prosecution; no need to prove breach caused harm.
    HSG274 Part 1: Technical Guidance for Cooling Towers
    HSE guidance document HSG274 Part 1 (Evaporative cooling systems) provides detailed technical guidance implementing ACOP L8 for cooling towers and evaporative condensers. It specifies: Legionella action levels (immediate investigation at 100 to 999 CFU per L, remedial action at above 1,000 CFU per L including hyperchlorination), clean-and-disinfect intervals (minimum annually and before extended shutdown), biocide programme requirements, and drift eliminator specification (below 0.002 percent drift rate).
    Notifiable Cooling Towers and Evaporative Condensers Regulations 1992
    UK Regulation SI 1992/2225 requires that all owners of cooling towers and evaporative condensers notify the local authority (environmental health department) of the existence, location, and nature of the system. Notifications must be updated when a system is commissioned, decommissioned, or substantially altered. This provides local authorities with information to trace potential sources of Legionella outbreaks to cooling towers in their jurisdiction during outbreak investigations.
    PSSR 2000: Pressure Systems Safety Regulations
    The Pressure Systems Safety Regulations 2000 apply to cooling systems containing pressurised water or steam above 0.5 bar gauge and above 250 bar-litres stored energy. Evaporative cooling towers themselves are not pressure vessels, but associated chiller condensers, pressurised refrigerant systems, and high-pressure hot water circuits fall under PSSR. A Written Scheme of Examination (WSE) prepared by a competent person is required, with periodic inspection by an inspection body (Lloyd's, Bureau Veritas, TUV) at intervals specified in the WSE.

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