RO desalinators force salty water against a semipermeable membrane which has pores so small they prevent the passage of relatively large materials such as sodium ions, potassium ions, and chloride ions, while allowing the passage of smaller water molecules. The pressures required are quite high, so that either a high pressure powered pump is needed (e.g., units usable aboard ships) or a strong arm on a long lever (e.g., the hand-operated ones). About a liter an hour for the hand-operated ones. At home, you'd pay money for a four-hour workout ... Silt clogs them, so a pre-filter is a must They grow algae, which clogs them. They leak. But, nothing else will do the job. A pdf source ... more than you want to know ... : http://www.practical-sailor.com/newspics/charts/881water.pdf The Pur Survivor-06: http://www.safetycentral.com/survivor06.html (about $US 600) And, the Katadyn 35: http://www.katadyn.ch/site/sg/home/marine/ou_products/survivor__35/ Google can make you knowledgeable ... -- Dave Kruger Astoria, OR -- ----- Original Message ----- From: "Paul Ash" <AshP_at_sundaytimes.co.za> > How do reverse osmosis pumps work? And what do they cost? I live in South > Africa where anything like this has to be imported and costs a bomb. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Tue Aug 17 2004 - 06:24:27 PDT
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