Improper cooling tower filtration can lead to serious illnesses.

Earlier this year, a woman living in the Washington Heights area of New York City filed a lawsuit against the Sugar Hill Project, the impressive $84 million subsidized housing building located in nearby Harlem. Completed in 2014, the mixed-use facility was designed to be an affordable living space for one of New York’s poorest communities, yet the development had one major issue that belied its high-minded, revitalization goals: it was getting people sick. 

Last summer, more than 50 people in the surrounding area were hospitalized resulting in 2 fatalities, all related to Legionnaire’s Disease. The outbreak was connected to the housing project’s cooling tower, which has since been shut down. If not properly filtered, cooling towers can instigate microbiological growth that can lead to health problems, such as those caused by Legionella.  

As an integral component of many cooling systems, cooling towers are typically used in industrial applications and in large commercial buildings to extract heat from a process or building system through evaporative cooling. Cooling tower systems operate most efficiently when their heat transfer surfaces are clean, but by design, require a large air-water interface to obtain this cooling and thus the system is subject to four major water treatment concerns: corrosion, scaling, fouling and microbiological activity. 

As waterborne deposits collect, they reduce heat transfer efficiency which can be very costly. Traditionally, the deposits are controlled by system blowdown, which increases wastewater discharge as well as concerns about water usage due to drought and environmental threat. As a result, cooling towers are being operated at higher contaminant concentrations, which only compound the problem. 

Addressing it involves full flow and side stream filtration. Filtration reduces blowdown, energy consumption and the kinds of fouling that leads to harmful microbial growth. Full flow filtration uses a filter installed after the cooling tower on the discharge side of the pump and is designed to continuously filter all of the recirculating system water. Side stream filtration continuously filters a percentage of the flow which significantly reduces system footprint, capital investment and operational cost — all very important considerations for affordable housing budgets. Additionally, these systems can be cleaned offline without shutting things down, eliminating the need for planned downtime. 

There is an array of filtration technologies available in the market, but few achieve adequate efficiencies. Screens require frequent backwash which increases water discharge. Hydroclones suspend solids through centrifugal force which can leave smaller particles behind. Sand filters can offload sand into the system. Bag filters have limited surface area, requiring large vessels to address flow requirements. All address some of the costs associated with inefficient cooling tower filtration, but in many cases introduce new ones.

Cartridge filters, on the other hand, address all costs: environmental, operating and health. They’re a disposable medium that exists in both non-pleated (lower cost, generally lower efficiencies) and pleated designs (high surface area) and offer high retention down to sub-micron levels, thus effectively addressing bio-burden issues. Some newer designs in the market such as large diameter offer further improvements in flow rates while reducing operating costs. 

In March, the New York City Council voted to reform the city’s cooling tower inspection protocol requiring the city’s Department of Buildings and Department of Health to present an annual report of cooling tower inspection results to the city council and post the results online. Cartridge filtration could play a critical role in those results, as well as the well-being of the surrounding Harlem and Washington Heights communities. The entire story is yet to be told, but it deserves a happy ending. Especially when one considers that the Sugar Hill Project has been designed with a Children’s Museum of Art and Storytelling at its base. 


Stratum™ A Series Absolute Rated Melt Blown Filter Cartridges   

•Absolute retention ratings from 0.5 to 70 microns

•Multi-zone melt blown depth filter with a graded pore structure for maximum dirt holding capacity •Thermally bonded fibers for high void volume and long on-stream life •Lot traceable filters come with certificate of conformance •100% polypropylene FDA listed materials of construction •All components meet USP Class VI criteria and are safe for use in pharmaceutical applications •Molded center core for higher temperature and pressure capability NSF logoCertified to NSF/ANSI 61 for materials requirements only – Component * Typical Applications »Water »Pharmaceuticals »Food and beverages »Microelectronics »Cosmetics »Polymers »Coatings * NSF 61 applies to NN, P6 and PX styles only

•Multi-zone melt blown depth filter with a graded pore structure for maximum dirt holding capacity •Thermally bonded fibers for high void volume and long on-stream life •Lot traceable filters come with certificate of conformance •100% polypropylene FDA listed materials of construction •All components meet USP Class VI criteria and are safe for use in pharmaceutical applications •Molded center core for higher temperature and pressure capability NSF logoCertified to NSF/ANSI 61 for materials requirements only – Component * Typical Applications »Water »Pharmaceuticals »Food and beverages »Microelectronics »Cosmetics »Polymers »Coatings * NSF 61 applies to NN, P6 and PX styles only

•Multi-zone melt blown depth filter with a graded pore structure for maximum dirt holding capacity •Thermally bonded fibers for high void volume and long on-stream life •Lot traceable filters come with certificate of conformance •100% polypropylene FDA listed materials of construction •All components meet USP Class VI criteria and are safe for use in pharmaceutical applications •Molded center core for higher temperature and pressure capability NSF logoCertified to NSF/ANSI 61 for materials requirements only – Component * Typical Applications »Water »Pharmaceuticals »Food and beverages »Microelectronics »Cosmetics »Polymers »Coatings * NSF 61 applies to NN, P6 and PX styles only


Gravex® is a complete product line of high-purity, quality-certified cation, anion and mixed bed ion exchange resins.

These custom-blended bead resins are the cleanest bead available, washed and classified, every batch tested and samples filed for future reference.

They are processed to meet nuclear specifications. We offer the most conclusive results available for nuclide removal products. Graver Technologies also supplies bead resin manufactured by Dow, Rohm & Haas and Lanxess (Bayer).

These Gravex Nuclear Grade Ion exchange resins are very high capacity polystyrene, gel type resins. They have been regenerated and processed to provide the highest possible performance in nuclear applications. The Gravex cation is specially processed to minimize leachable sulfonic acids.

Its high capacity and oxidative stability help achieve optimal performance. Gravex mixed beds are the most uniformly blended products available and have the same consistent cation to anion ratio in every package. Our unique blending process creates the less separable GR-3-16 NG stoichiometric mixed bed. A 7Li+ form cation is available as GR-7-16 NG and in the GR-4-7 NG mixed bed.

Proven Technology for the Most Challenging Separations

Combined Cycle Power Generation

Condensate polishing (CP) is an essential component of combined cycle plant design and operation because high purity condensate maximizes uptime. CP safeguards high-value plant assets by reducing startup/downtime, stabilizing cycle chemistry, minimizing corrosion transport and optimizing operations.

CP is particularly important for air-cooled condenser (ACC) systems, once through steam generators and plants with frequent startups. Utilities can’t afford to ignore this vital and economical system that consumes a tiny portion – typically 1% – of plant construction budgets.Electric generating station condensate must be maintained at a very high purity level to protect boilers, steam generators, reactors, and turbines from corrosion.

To remove contaminants from the condensate, deep bed ion exchange condensate polishers are used and sometimes preceded by a Powdex® filter demineralizer or a fine particulate filtration system. A Powdex system can also stand alone as the primary polisher. Graver Technologies is the most experienced and knowledgeable Ion Exchange product and Filter Septum manufacturer and offers the most complete range of products to meet today’s challenges.

Whether the need is for high purity condensate polishing bead or powdered ion exchange resins or filter elements specially designed for condensate polishing, Graver Technologies has the answer for your application.

Powdex® Powdered Resins

Powdex® PAO Series

  • Powdered strongly basic hydroxide form anion exchange resin
  • Highest possible conversion to hydroxide form with very high purity
  • Mixed at point of use with Powdex PCH or PCN to form larger agglomerates
  • Then precoated on Aegis® wound and DualGuard® precoat septa and others in precoat filtration systems known as Powdex filter demineralizers
  • Rapid kinetic performance with excellent hydraulic properties providing simultaneous ion exchange and solids filtration
  • Excellent precoat uniformity essential for proper performance

Typical Applications

  • Nuclear BWR & PWR condensate polishing
  • Nuclear BWR reactor water cleanup
  • Fossil condensate polishing

Click here to download Powdex® Selection Guide.


Graver Technologies, LLC introduces TurboGuard, its technically improved 6 inch (152 mm) high-flow filter for the utility market. Graver is the world’s largest supplier of condensate system filters and components and has been manufacturing precoat and non-precoat septa for condensate systems for more than 50 years. Graver is the consistent technology innovator with more than 40 patents and numerous technical advances for condensate and high purity water applications.

Graver’s family of TurboGuard High Flow Filters will provide superior CRUD removal upstream of deep bed demineralizers. TurboGuard High Flow Filters may also be used following ion exchange beds as a resin trap,
or as highly efficient pre-filters before membrane systems. Graver’s TurboGuard line of filters are manufactured in the USA at Graver Technologies manufacturing plants, under an ISO-9001 (2000) quality system.

Graver’s TurboGuard High Flow Filter integrates a number of improvements over currently available elements. With the most experience of any supplier in condensate applications, Graver can access more than 50 years of experience when improving fundamental filtration in condensate and high purity water applications.

AEGIS® TurboGuard® Pre-Filters

  • Flow is from the inside core to the outer pleats
  • TurboGuard Filters are wrapped in a one-piece extruded outer cage preventing media migration during inside out flow
  • TurboGuard’s one-piece extruded outer cage allows for easier maintenance and removal after use
  • One-piece molded end caps, including molded-in bail for secure handling during installation and removal
  • Quad Seal gasket system to provide maximum sealing surfaces
  • Highest dirt holding capacity – approximately 25 lbs (11.5 Kg) before removal is required
  • Low pressure drop – less than 0.2 bar in service at specified flow rate
  • Optimized media surface area allows full use of installed media area – not blocked off by media “squeezing

Typical Applications

  • Pre-filter for protection of Deep Bed demineralizers
  • Pre-filter for protection of RO membranes
  • Retrofit OEM high flow large geometry filter housings

Power Generation Systems — The Right Septa Choice


Graver Water  has optimized deep bed condensate polishing technologies through the use of proprietary flow distribution enhancements and enhanced collection, to maximize resin utilization. For on-site regenerated systems Graver’s trademarked and proprietary two-vessel SepraEight® regeneration design results in a smaller footprint for regeneration equipment without compromising separation efficiency or optimum regeneration.

Deep bed/mixed bed condensate polishers are the preferred technology for plants using high TDS cooling waters such as seawater, as well as where there is a requirement to operate long term with small condenser leaks or an inability to control excessive air in-leakage.

Both Deep Bed and Precoat type Polishers remove iron, copper, silica and salts, and suspended solids. However, Deep Bed Polishers provide the best method for the removal of high ionic loads due to their large ion exchange capacity. Graver’s Deep Bed Condensate Polishers have been designed to handle service pressures of up to 800psi with inlet distributors and underdrain that operate more efficiently than competitive designs.


Ion exchange resin selection and ratios can be optimized for the particular application and condensate chemistry. For instance when “All Volatile Treatment” (AVT) is used the result is an elevated operating pH (amine level) the resin ratio of choice would be a high cation exchange to anion exchange resin ratio (2:1) when in a neutral pH environment, as would be seen in a boiling water reactor (BWR) a stoichiometric blend of the ion exchange media would be employed. Upon exhaustion, either due to ionic breakthrough or pressure drop, the units are regenerated though a series of backwash, chemical regenerants (either in situ, external or off site) and then returned to service.

When Deep Bed Condensate Polishers are paired with a quality ion exchange resin such as Gravex® Bead Resin, efficient polishing of condensate is easily obtained. When the exchange capacity of the resin is exhausted it can either be sent off-site for regeneration or disposal, or it can be regenerated on-site using Graver’s SepraEight technology.


  • High ionic loading removal
  • Up to 800psi service pressure
  • Up to 50 gpm/sq. ft. flowrate
  • Superior resin regeneration


NANODEX FILTER PAPERS TRACK SYSTEM AND PLANT PERFORMANCE by Monitoring Radionuclide and Corrosion Products

Graver’s patented Nanodex Ion Exchange Filter Papers enable diverse quantitative analyses in the power industry, especially nuclear, to monitor corrosion products, measure activity levels and satisfy fuel warranty requirements.

Nanodex AX 100 anion exchange filter disks contain strongly basic, quaternary ammonium functional sites in the chloride form, which can be converted to the desired ionic form (i.e. hydroxide) as required.

Nanodex CX 200 cation exchange filter disks contain strongly acidic, sulfonic acid functional sites in the hydrogen form. Contact your Graver representative for more information about these innovative filter papers.


  • High performance, specialty hydrophilic paper for a variety of analytical requirements
  • Uniform resin distribution throughout each disk
  • Standard 47mm diameter
  • Highly functionalised, highest ion exchange capacity analytical filter
    disks available
    Filter disks are easily digested by standard analytical methods


  • Excellent hydraulic characteristics
  • Consistent ion exchange capacity and utilization
  • Fit standard bench-top and inline filter holders and housings
  • Single disk used per test
  • Simple to quantify ions removed – X-ray fluorescence or Atomic Absorption
Filter Cartridges

QMA Polypropylene Filter Series

“Absolute” Rated High Performance Pleated Polypropylene Filter Cartridge

This filter is manufactured with a multilayer, graded densityasymmetric melt blown polypropylene media. This unique structure allows for low initial pressure drop and high dirtholding capacity, and long high efficient service.

Filter Features–Benefits

  • Micron ratings from 0.20 to 10 μm– Broad application rang
  • Meets USP 24 Class VI biological test for plastics
  • “Absolute” Efficiency – Rated at 99.98% (Beta 5000)
  • Graded pore density – Multilayer, graded density media – asymmetric pores for high dirt holding capacity
  • High surface area – High flow rate, and long on-line service – Minimize maintenance cost
  • Fixed Pore construction – Eliminates dirt unloading at maximum differential pressure
  • Polypropylene Construction – Inert to many process fluids
  • Various Gasket/O-ring materials – Compatible with many fluids
  • Heavy duty molded cage – High structural strength 


• Food & beverage • Aqueous solutions • Chemicals• Blowdown post filter • Pharmaceutical • Cosmetics • Magnetic tape coatings • RO Prefilters • Ink

FDA compliance
All polypropylene material used in manufacturing complies with the regulations of the FDA title 21 of the Code of Federal Regulations Sections 174.5, 177.1520, and 177.1630, as applicable for food and beverage contact.

TefTEC PTFE Membrane Filter Series

Absolute Rated PTFE Membrane Filter Cartridge

TefTEC cartridge filters are constructed with naturally hydrophobic PTFE membrane and polypropylene support layers and components. The HIMA retentive PTFE membrane offers superior hydrophobicity and water intrusion resistance compared to PVDF and polypropylene membranes, and the cartridge construction offers a cost-effective alternative to all fluorocarbon filters. TefTEC filters are ideal for gas/vent applications and the filtration of aggressive chemicals and solvents.

TefTEC Filter Features–Benefits

  • High surface area, single-layer construction provides superior flow rates and minimizes filtration system size
  • 100% Flushed with DI water and integrity tested
  • Meets applicable CFR criteria and USP Class VI Biological Test for Plastics
  • Filters are manufactured in an ISO Class 7 Cleanroom Environment
  • Filters are flushed, tested and packaged in a Class ISO 7 clean room
  • Manufactured using current Good Manufacturing Practices
  • Each filter element stamped with pore size, lot and serial number for identification and traceability


Aggressive chemicals • Tank Vents • Strong acids/bases • Compressed gases • Solvents • Photoresists • Pharmaceutical Intermediates • Hot DI water • Fermentation air