SpectraPure
SpectraPure®Inc.
480.894.5437 Call us toll-free 1.800.685.2783
2167 East Fifth St, Tempe, Arizona 85281
®
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Membrane Output Calculation
Membranes produce the rated gallons per day (GPD) at 60 psi (4.1 bars)
operating pressure, 77°F (25°C) operating temperature and 500 ppm total
dissolved solids.
Membrane output gallons per day (GPD) depends on operating pressure, water
temperature and the ppm TDS in the feed water.
Expected GPD = Rated GPD × PCF × TCF
PCF is the pressure correction factor
TCF is the temperature correction factor
Calculation of Pressure Correction Factor (PCF): The output (GPD) from
the membrane is directly proportional to the applied pressure.
Note: The membrane is rated to produce the rated GPD at 60 psi. For any pres-
sure other than 60 psi the output GPD is multipled by the PCF.
PCF = Line Pressure (in psi) ÷ 60
Calculation of Temperature Correction Factor (TCF): The output (GPD)
also decreases with decrease in temperature. This is because water viscosity
increases with decrease in water temperature.
Temperature Correction Factor Table (TCF)
°F /°C TCF °F \°C TCF °F \°C TCF
41.0 /5 0.521 59.0 /15 0.730 77.0 /25 1.000
42.8 /6 0.540 60.8 /16 0.754 78.8 /26 1.031
44.6 /7 0.560 62.6 /17 0.779 80.6 /27 1.063
46.4 /8 0.578 64.4 /18 0.804 82.4 /28 1.094
48.2 /9 0.598 66.2 /19 0.830 84.2 /29 1.127
50.0 /10 0.620 68.0 /20 0.857 86.0 /30 1.161
51.8 /11 0.640 69.8 /21 0.884 87.8 /31 1.196
53.6 /12 0.661 71.6 /22 0.912 89.6 /32 1.232
55.4 /13 0.684 73.4 /23 0.941 91.4 /33 1.267
57.2/14 0.707 75.2 /24 0.970 93.2 /34 1.304
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