Specifications

Table 2 which corresponds to the measured flow rate to
the 77°F (25°C) standard as follows:
Adjusted Measured Temperature
Flow = Flow ÷ Correction
Rate Rate Factor
As an example, if the above system is producing 8 gpd at
60°F, the Temperature Correction Factor from Table 2 is 0.69.
8 gpd ÷ 0.69 = 11.6 gpd @ 77°F
The TDS levels of the product and feed water were
measured in the previous section. To accurately predict the
performance of the RO module, the feed water pressure must
be adjusted to account for osmotic pressure. Calculate
osmotic pressure as follows:
Osmotic Pressure = 1 psi for every 100 mg/L TDS
From the previous example system:
1000 ÷ 100 = 10 psi Osmotic Pressure
Since osmotic pressure acts as back pressure against the RO
process, it is subtracted from the measured feed water pres-
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AQUA-CLEER
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/GOOD WATER MACHINE
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DRINKING WATER SYSTEMS
sure to determine the effective module pressure. Measure
the feed water pressure and calculate the effective module
pressure as follows:
Effective Module = Measured - Osmotic
Pressure Pressure Pressure
If the pressure measured from our example system is 60 psi:
60 - 10 = 50 psi Effective Module Pressure
Using the effective module pressure, read the standard prod-
uct flow rate from the flow graph in (Fig. 13). For our
example system, we find the standard product flow is 35 gpd
at 50 psi. Comparing this to the adjusted flow rate, we find the
example system operating within the limits of the
published standard.
Checking Quantity Stored
To predict the volume of water which will be stored by the
system, it is necessary to determine the approximate product
water pressure at which the system considers the tank full
and the automatic shutoff actuates.
Feed Water Pressure x 0.6 = Shutoff Pressure
FIG. 13
=—