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Old 11/06/2009, 12:42 PM   #1
SpectraPure
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Join Date: Jun 2003
Posts: 4,657
How do I calculate my membrane production?

How do I calculate my membrane output?
Membranes produce the rated gallons per day (GPD) at 60 psi (4.1 bars)
operating pressure, 77F (25C) 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 pressure
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

bruce


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