Permeate flux is the rate of permeate flow per unit membrane area, in gallons per square foot per day (GFD) or liters per square meter per hour (LMH). SWRO design flux is 7–9 GFD (12–15 LMH); BWRO 15–25 GFD (25–42 LMH). Flux is set by membrane area, feed pressure, temperature, and fouling state. Lower flux per element extends membrane life but raises capital cost; higher flux compresses capex but accelerates fouling. Design flux is the single biggest tradeoff in array sizing. Over-flux causes premature fouling and warranty problems; under-flux wastes capex. 1 GFD ≈ 1.7 LMH. To convert GFD → LMH multiply by 1.7; LMH → GFD multiply by 0.59. High flux accelerates concentration polarization and biofouling. Membrane manufacturers void warranty above 9 GFD on standard SWRO elements. Yes — temperature- and pressure-normalized flux is the standard fouling indicator. A 10% normalized flux drop is the industry CIP trigger. ForeverPure has supplied desalination, high-pressure pumps, and energy-recovery devices to commercial and industrial customers since 2003. Contact our engineers for sizing, quotes, or technical support.Permeate Flux (GFD / LMH)
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