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Cross flow membrane filtration is now common in industrial and commercial water filtration applications. It is an effective means of separating the constituents of a wastewater stream. Membrane filtration is found in many industries, including food processing, metal working, parts cleaning, pulp and paper, plating, truck and car washes, die casting, printing, textiles and chemical
processes.
Membrane filter processes are classified on the basis of the size of particles filtered. In order of decreasing particle sizes: microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO).
Of these, reverse osmosis provides the purest water. The water is of almost potable quality, since the membrane can be specified to pass molecules as small as 10 Daltons. This eliminates almost all potential impurities, including all known organic or biological impurities. RO is a preferred technique for producing ultra pure water for semiconductor fabrication processes.
The means of control in all cases is pressure differential between the influent (feed) and the effluent (permeate). This pressure differential can be from 20 to 80 psi in micro-filtration up to 400 to 1000 psi in reverse osmosis.
APG pressure transmitters and gauges can be used to control membrane filtration processes. APG ultrasonic or float-type level controls may be used on feedwater tanks. |
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Reverse Osmosis Filtration
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Self-powered by standard 9 V battery |
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Large, full 4-digit display with 0.5 in. characters |
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microprocessor auto zero, peak hold and alarm |
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Ranges: vacuum to 10,000 psi |
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Direct reading to 9,999 psi |
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+/- .25% accuracy of full scale (on selected ranges) |
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Optional +/-0.1% accuracy of full scale with NIST certification (on selected ranges)
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