Basic Principles
103
Cat. No. 01023095
The rest of the feed water contains the dissolved solids removed from the product water, in addition to the dissolved solids
already present in the feed water. This concentrate water is sent to drain.
The amount of total dissolved solids rejected by the system is expressed as a percentage. A 90% rejection means that
90% of the dissolved solids have been removed from the feed water by the system. To calculate the percent rejection, use
the following equation:
(Feed TDS - Product TDS)
(Feed TDS)
x 100 = % Rejection
Where Feed TDS is the total dissolved solids content of the water going into the system, and Product TDS is the total dis-
solved solids content of the high quality product water. The GBE RO controller displays the Product TDS (TDS OUT) on
the information screen. The feed TDS needs to be measured with a handheld meter.
For example, if the Feed TDS is 600 ppm and the Product TDS is 24 ppm,
600-24
600
x 100 = 96% Rejection
NOTE Numbers used in these examples might not reflect those of your unit.
The amount of high quality water recovered for use as a percentage of the water fed into the reverse osmosis system
is called percent recovery. The GBE RO controller displays the Feed Flow (FFLOW) and Product Flow (PFLOW) on the
Information screen. The Recovery is also displayed on an Information screen. Use the following equation to calculate
percent recovery:
Product Water Flow Rate (PFLOW)
Feed Water Flow Rate (FFLOW)
x 100 = % Recovery
CAUTION! An understanding of rejection/recovery percentages and temperature compensation
is essential for monitoring and evaluating the performance or condition of the reverse
osmosis system. DO NOT operate the system before becoming familiar with these
concepts.
Temperature Compensation
As the feed water temperature decreases so will the product water production. The rated product flow (gallons per minute,
gpm) as shown for the various models is based upon the feed water temperature equal to 77° F.
Feed Water Limits
used for pretreatment.
Property
Minimum
Maximum
Turbidity (NTU)
0.0
1.0
pH*
6
11
Chlorine (ppm)
0.0
0.1
Total Dissolved Solids (ppm)
50
2500
Temperature (°F)
33
100
Silt Density Index
0.0
5.0
Iron (ppm)
0.0
0.1
Table 10.
Feed water limits.
*Short term cleaning is acceptable for pH ranges between 2.0/12.0. Additional treatment is required when chloramines are
present and the pH levels exceed 9.0.
NOTICE
In some applications, a water softener is not required. Consult an independently operated Culligan
dealer for further information on these special applications.