From Yardney Filters:
In applications where water is being pumped, re-circulated and re-used, water quality maintenance is always a problem. The re-used water becomes fouled with air borne environmental contaminants such as dirt, grit and sand. Add to this biological growth within the water environment such as algae, bacterial slime and other organic constituents and you have a challenging water quality management problem. Many traditional approaches have been to periodically discharge a portion (or all) of the water from the system, treat it with chemicals, add fresh water and live with the symptoms. The cause of the problem, the contamination, was never really addressed.
In the environmentally sensitive world of today these unsound treatment practices of chemical usage and excessive waste discharge do not make sense. Beyond that, none of these traditional treatment approaches do anything to enhance system performance and efficiency. Yardney packaged or field assembled filtration systems eliminate the cause of these problems, inorganic and organic contamination. Yardney recirculation filtration systems, whether used in cooling towers, water basins, cooling loops, cooling ponds, architectural ponds, water features, car washes, etc. remove the dirt rather than mask the symptoms.
Yardney filtration systems are configured to remove the suspended solids down to the level of filtration that you request. For cooling applications this is typically in the 10-25 micron range, although some users will want to filter down to 5 microns. Yardney automatic systems entrap and remove the suspended solids in the flow stream, accumulate them and periodically backwash out the concentrated accumulated dirt. The process is extremely efficient typically consuming less than 1/4 of 1% of the total amount of water processed for the cleaning sequence.
In HVAC/Cooling Tower applications the backwash water actually becomes part of your blow down water calculation. Therefore the backwash water merely becomes part of the blow down water volume. The best news is that by using the Yardney filtration system to remove the suspended solids rather than fully depending upon blow down to remove them, blow down rates typically can be reduced by 40% to 60%.
With the 40%-60% savings in water and chemicals, the systems typically pay for themselves in 12-15 months or less. Other secondary benefits include the elimination of mucking out basins and reservoirs. By removing the dirt from the system on a continuous basis heat exchangers, condensers and heat transfer surfaces do not become fouled which results in optimized heat transfer and no costly heat exchanger tear down for cleaning.