Installing cleanable filters on cooling tower air-inlet louvers can help minimize maintenance requirements by keeping contaminants out of the cooling system.

For the past 60 years, Osram Sylvania Inc. has been a major innovator and supplier of powder technology, high-temperature metallurgy and inorganic chemistry used in the manufacture of lighting products, automotive and electronic parts, and defense systems. Its largest factory, located in Towanda, Pa., sits on 65 acres along the shores of the Susquehanna River. The plant processes tungsten minerals and molybdenum (stranded wire) materials, which are critical components in products ranging from the filament wires found in standard light bulbs and electron emitters for defense system electronic devices, to armor-piercing bullets, rocket-engine nozzles and other high-temperature jet engine components for military and aerospace applications.

Although the towers at the Osram Sylvania plant are designed for outdoor use in an industrial manufacturing location, large concentrations of contaminants and debris were fouling the recirculation system.

Tungsten processing begins by milling crushed ore powder and continues through wiredrawing and high-temperature metallurgy. The plant runs its process cooling towers around the clock as a relatively inexpensive and dependable means of removing heat from cooling water used to supply cool air for equipment and facility occupants. Additional towers cool the circulating water used in high-temperature metallurgy processing methods.

Although the towers at the Osram Sylvania plant were designed for outdoor use in industrial manufacturing locations, large concentrations of contaminants and debris were fouling the recirculation system. The towers use a closed-loop approach, mixing air and water, which allows contaminants to transfer to the inline filtration system. Naturally occurring environmental elements such as cottonwood seeds and bugs, as well as process-generated debris such as metallic dust particles, frequently blocked the inline filtration system, causing an automatic shutdown of the whole processing system. Maintenance personnel were being called out daily to take the system apart and clean the strainers.

To avoid problems with icing in the winter, E.M. Cahill developed a simple steel holding frame system that extends the filter media beyond the area where the water freezes in the cooling towers.

Simple Equipment Protection

Gary Wilcox, production supervisor for Osram Sylvania, considered using a chemical additive in the loop to help break down the contaminants and prevent them from plugging the inline strainer. However, this option presented a high recurring consumable expense along with potential environmental issues. Besides monitoring the quality of the wastewater discharged into the sewer system, the plant would need to investigate and comply with any regulations and record-keeping demands of governmental bodies such as the Environmental Protection Agency.

Wilcox contacted E.M. Cahill Co. Inc., a sales agency headquartered in Syracuse, N.Y., that helps plants contain costs by standardizing filters, reducing labor hours, and improving ventilation efficiencies with preventive maintenance and customized filtration programs. After a site evaluation and a few simple measurements, E.M. Cahill recommended attaching cleanable, electrostatic equipment protection filters from Permatron Corp., Elk Grove Village, Ill., to the multiple air inlet louvers. According to company president Mike Cahill, the nominal cost of the media, called PreVent, and the ease of installation would allow the filters to provide quick payback by reducing the plant’s maintenance costs and increasing process uptime. The filters could be used outdoors year-round and could be mounted on the equipment by Osram Sylvania’s in-house maintenance staff.

The filter captures debris before it can enter the air-intake louvers.

At the Towanda plant, water trickles down continuously in the cooling towers close to the air-intake louvers. This water often turns to ice in the cold Northeastern winters. E.M. Cahill developed a simple steel holding frame system that extends the filter media beyond the area where the water freezes, thereby ensuring that the filters do not become clogged by ice.

After more than six months of using the filters, the processing and maintenance staff is happy with the air-intake filtration solution. The cooling tower system is not automatically shutting down costly operations, and maintenance has been reduced simply to brushing the debris off the filter with a broom, without any system downtime.

“These filters have saved us money, reduced downtime and to date eliminated any possible environmental outages,” said Wilcox.PC

For more information from Permatron Corp., Elk Grove Village, Ill., call (847) 434-1421, e-mail or visit For more information from E.M. Cahill Co. Inc., Syracuse, N.Y., call (315) 472-5050 or