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19
SpectraPure
®
Membrane Output Calculation
Membranes produce the rated gallons per day (GPD) at 60 psi (4.1 bars) operat-
ing 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
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
TESTING THE QUALITY OF THE MEMBRANE:
