Typically closed loop water circuits employed as part of the environmental control systems, will be contaminated with suspended solids produced by the corrosion of pipework and other components of the system. This contamination can cause abrasive wear and tear, foul heat exchangers and affect the operation of valves, which can result in poor temperature control within the building. The problem is often increased due to contamination by water-born microorganisms such as Pseudomonas. Circulating bacteria or biofilm coating pipework can be chemically treated with biocides, but although this process may hinder further proliferation of bacteria, the ‘dead’ material will add to the quantity of recirculating particulate matter. Amazon Filters recommends the use of Side Stream filtration systems to help solve these problems. The use of these systems is also recommended by the Building Services Research and Information Association (BSRIA publication AG 1/2001: Pre-commission Cleaning of Pipework Systems ; Parsloe C) for both the initial clean up and for the ongoing maintenance of pipe work systems. We have designed and supplied systems for LTHW, CHW and condensate circuits.
Side Stream System Design
A Side Stream filtration system is designed to treat 5 - 15% of the main water circuit flow, to remove both suspended solids and the chemically treated biomass. A typical system would consist of an Amazon Stainless Steel 61 Series filter housing containing disposable Amazon SupaSpun II filter cartridges.
SupaSpun II filters are available in a range of absolute micron ratings so the removal efficiency can be adjusted so as to achieve a progressive clean up of the recirculating water. Typically a 20 µm rate filter is used for the initial clean up. Once this is achieved a finer filter can be used e.g.10 µm absolute. We recommend the use of absolute rated filters as unlike nominal filters they maintain their removal efficiency for contaminants throughout the lifetime of the filter, even under varying water quality conditions. It is typical for nominal filters to suffer reduced removal efficiency or to unload previously retained contaminants after a period of use and this will cause unexpected system fouling.
Side Stream filters are typically installed inside in the Building Plant Room. For ease of operation, a variety of operator friendly accessories are fitted to the vessels to make installation, operation and filter change-out as simple as possible. These include drain valves, pressure gauges, vent valves and on certain applications with high iron content, Rare Earth Ferrostik magnetic assemblies for removal of iron based contaminants. An automatic vent valve can also be incorporated on the filter housing to help eliminate trapped air from the system.
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