Reverse Osmosis Permeate Flux & Recovery Calculator
Model industrial RO membrane flux (GFD / LMH), system recovery rate, feed and reject brine flows, and temperature correction factor (TCF).
Permeate Production & Recovery
Membrane Element Quantity & Area
Flux & Hydraulic Performance
Temperature & Membrane Area
Membrane Life & Scaling Assessment
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
What is Permeate Flux in Reverse Osmosis and why is it measured in GFD?
Permeate flux is the rate of purified water flow passing through a unit area of membrane surface per day, expressed as GFD (Gallons per Square Foot per Day) or LMH (Liters per square meter per hour). It is the central parameter governing membrane longevity, fouling rate, and cleaning frequency.
Why must feed water temperature be corrected with TCF?
As water cools, its viscosity increases (water is ~40% more viscous at 50°F than at 77°F). In colder water, higher net driving pressure is required to push the same volume of water through the polyamide polymer pores. Sizing without TCF will leave a plant starved for water in winter months.
What is the relationship between recovery rate and brine concentration factor?
System recovery (Y) is the percentage of incoming feed water converted into pure permeate. The reject concentration factor equals 1 / (1 - Y). At 75% recovery, minerals in the concentrate stream are concentrated 4 times; at 85% recovery, they are concentrated 6.67 times, greatly increasing calcium sulfate and silica scaling potential.
What happens if design flux is set too high?
Excessive flux causes severe concentration polarization—an impenetrable boundary layer of concentrated salts and colloids right against the membrane surface. This causes rapid irreversible mineral scaling, biofouling, and loss of salt rejection.