Mass Flux Density Converter

Mass Flux Density (also known as Mass Flux Rate, Mass Velocity, or Superficial Mass Velocity, symbolized by G, j_m, or J) measures the rate of mass flow passing perpendicularly through a unit cross-sectional area per unit of time (G = ˙m ÷ A = (dm ÷ dt) ÷ A = ρ · v, where ρ is fluid density and v is mean fluid velocity). Across industrial reverse osmosis (RO) membrane water desalination, chemical packed absorption column gas-liquid contacting, industrial convective drying, fluidized bed combustion, environmental lake evaporation, and rocket nozzle gas dynamics, mass flux density is categorized across three major engineering unit families: International System of Units (SI metric fundamental: Kilograms per Second per Square Meter / kg/(s·m²), Grams per Second per Square Meter / g/(s·m²), Kilograms per Hour per Square Meter / kg/(h·m²)), Imperial / US Customary standards (Pounds per Hour per Square Foot / lb/(h·ft²), Pounds per Second per Square Foot / lb/(s·ft²), Kilograms per Hour per Square Foot / kg/(h·ft²)), and high-intensity laboratory metrics (Grams per Second per Sq. Centimeter / g/(s·cm²)).

Our free online Mass Flux Density Converter provides instant, high-precision conversions across all SI metric, Imperial chemical process, membrane filtration, and mass transfer units:

• Pounds per Hour per Square Foot to g/(s·m²) [Process Mass Transfer Standard]: Multiply lb/(h·ft²) by 1.35622991 (1 lb/(h·ft²) = 1.35623 g/(s·m²) = 0.00135623 kg/(s·m²) = 4.88243 kg/(h·m²)).
• Grams per Second per Square Meter to lb/(h·ft²): Multiply g/(s·m²) by 0.7373383 (1 g/(s·m²) = 0.73734 lb/(h·ft²) = 0.001 kg/(s·m²) = 3.60 kg/(h·m²)).
• Kilograms per Second per Square Meter to g/(s·m²) & lb/(h·ft²): 1 kg/(s·m2) = 1,000.0 g/(s·m2) = 737.3383 lb/(h·ft2) = 3,600.0 kg/(h·m2).
• Kilograms per Hour per Square Meter to g/(s·m²) [Membrane Flux Standard]: Multiply kg/(h·m²) by 0.27777778 (1 kg/(h·m²) = 0.27778 g/(s·m²) = 0.20482 lb/(h·ft²)).
• Grams per Second per Sq. Centimeter [g/(s·cm²)] to kg/(s·m²): Multiply by 10.0 (1 g/(s·cm²) = 10.0 kg/(s·m²) = 10,000 g/(s·m²) = 7,373.38 lb/(h·ft²)).
• Pounds per Second per Square Foot [lb/(s·ft²)] to g/(s·m²): Multiply by 4,882.42769 (1 lb/(s·ft²) = 4,882.43 g/(s·m²) = 4.88243 kg/(s·m²) = 3,600 lb/(h·ft²)).

Master Mass Flux Density Conversion Table

The table below displays exact mathematical conversion relationships, SI g/(s·m²) multipliers, and imperial lb/(h·ft²) equivalents relative to 1 Gram per Second per Square Meter (1 g/(s·m²) = 0.001 kg/(s·m²)):

Step-by-Step Industrial RO Desalination Membrane Water Flux Calculation Example

To convert an industrial Reverse Osmosis (RO) seawater desalination membrane producing a clean permeate water flux of 25.0 Kilograms per Hour per Square Meter (25.0 kg/(h·m²) or Liters/m²/h – LMH) into SI g/(s·m2), SI kg/(s·m2), and Imperial lb/(h·ft2):

Step 1 (SI g/(s·m2) Conversion): G = 25.0 × 0.27777778 = 6.9444 g/(s·m2) (6.94 g/(s·m2))

Step 2 (SI kg/(s·m2) Conversion): G = 6.9444 ÷ 1,000 = 0.0069444 kg/(s·m2)

Step 3 (Imperial lb/(h·ft2) Conversion): G = 25.0 × 0.204816 = 5.1204 lb/(h·ft2)

Thus, an RO membrane flux of 25.0 kg/(h·m²) yields 6.94 g/(s·m²) or 5.12 lb/(h·ft²) of clean permeate water.

Real-World Membrane & Process Mass Flux Density Benchmarks

Below is a comparative reference chart showing mass flux density values (G) across RO membranes, surface evaporation, packed columns, and rocket nozzles:

History & Physics: 1855 Adolf Fick Diffusion Law vs Superficial Mass Velocity (G = ρ · v)

1855 Adolf Fick & Fick’s First Law of Mass Diffusion (J = -D · (dC ÷ dx))

In 1855, German physiologist and physicist Adolf Fick published Ueber Diffusion, establishing the fundamental law of molecular mass transfer: J = -D · (dC ÷ dx). Fick proved that mass diffusion flux density J (in g/(s·m²) or kg/(s·m²)) is directly proportional to concentration gradient dC ÷ dx, establishing the physical foundation of mass transfer theory.

Superficial Mass Velocity in Heat & Mass Transfer Correlations (G = ρ · v)

In chemical process engineering and multiphase fluid dynamics, fluid movement through packed beds, heat exchangers, and distillation columns is calculated using Superficial Mass Velocity (G = ρ · v) in kg/(s·m²) or lb/(h·ft²). Because mass flux density G remains constant along variable-area or changing-density conduits under steady state, using G simplifies Reynolds (Re = G · D ÷ μ), Nusselt, and Sherwood number empirical correlations.

Popular direct tools:

• Conversion Calculator Main Directory
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Frequently Asked Questions (FAQ)

How do you convert lb/(h·ft²) to g/(s·m²)?

To convert Mass Flux Density from lb/(h·ft²) to g/(s·m²), multiply by 1.356230. For example, 100 lb/(h·ft²) × 1.356230 = 135.62 g/(s·m²).

How do you convert kg/(h·m²) (LMH) to g/(s·m²)?

To convert Reverse Osmosis membrane flux in kg/(h·m²) to g/(s·m²), divide by 3.6 (or multiply by 0.277778). For example, an RO flux of 18 kg/(h·m²) ÷ 3.6 = 5.0 g/(s·m²).

What is the difference between Volumetric Flow Rate (Q) and Mass Flux Density (G)?

Volumetric Flow Rate (Q in m³/s or GPM) measures total volume per unit time. Mass Flux Density (G in kg/(s·m²) or lb/(h·ft²)) measures mass flow rate per unit cross-sectional area: G = (Q · ρ) ÷ A = ρ · v.

Why is Mass Flux Density important in Reverse Osmosis (RO) membranes?

In RO membrane water treatment, permeate water flux is measured in kg/(h·m²) (LMH) or lb/(h·ft²). Operating within optimal mass flux limits prevents membrane fouling, concentration polarization, and structural compaction.