Flux or Water Flux - Reverse Osmosis Systems Print E-mail

Flux or Water Flux - Flux or water flux is typically expressed as volume per area per unit of time. Flux is used to express the rate at which water permeates a reverse osmosis membrane. Typical units of measurement are gallons per square foot per day (i.e. GFD or GSFD) or litres per square meter per hour (l/m2/hr).

The flux of a RO membrane is directly proportional to temperature and pressure. As a rule of thumb, flux decreases by about 1.5% per 1oF.

Salt flux is the amount of TDS that has passed through a given area of membrane per unit of time. It is important to remember that Salt flux is a function of concentration gradient and not driving pressure. Therefore with increasing driving pressure, the concentration of salts in the permeate decreases due to constant salt leakage (e.g., milligrams) and increased water flux (e.g. liters). The net effect of increased drive pressure is to dilute a constant amount of salt with more pure water.

Note: 1 GFD = 1.66 l/m2/hr

Technical support and advice

Reverse Osmosis Chemicals International work closely with a diverse range of global organisations, intelligently combining advanced treatment technologies with practical solutions to resolve complex issues. If you have a project you would like to discuss, or you require technical support and assistance; or if you simply have a question about our reverse osmosis technology solutions please contact one of our specialist advisors using our Technical Support page or call us on +44 (0) 330 223 31 31.