10
2.5.
Feed Water Requirements
The following feed water requirements must be met before installing your new E4
machine to ensure quality permeate and extended membrane element life. Refer to
Table 3 for feed water information.
Table 3.
Feed Water Requirements
Temperature
Typical: 50-85
F (10-29
C)
Maximum: 32-104
F (0-40
C)
Inlet Pressure
Minimum 30 psig (2.1 bar)
Maximum 60 psig (4.1 bar)
Chlorine (continuous feed)
0 ppm
Operating pH
For soft water (less than 1 grain per gallon (gpg) or 17
mg/L hardness), acceptable pH is 4.0-11.0.
For unsoftened water (contact factory with water
analysis, acceptable pH is 5.5-6.0.
For short term (cleaning) a pH range of 2-12 is
acceptable.
Silt Density Index (SDI)
Less than or equal to 3 to minimize membrane fouling
and extend cleaning intervals. Refer to ASTM standard
D4189.
*American Standard for Testing Materials
2.6.
Transporting Pure Water (Permeate) to Point-of-Use
The pure water, or permeate, is in an aggressive state and should only be transported
from the machine to the point-of-use in food grade flexible nylon, stainless steel (SS)
tubing, or polyvinyl chloride (PVC) material for the inlet, permeate, and concentrate
piping sizes. Refer to Connections (Table 2) for inlet, permeate, and concentrate piping
sizes.
WARNING: MACHINE DAMAGE MAY OCCUR IF PERMEATE BACK PRESSURE EXCEEDS
60 PSIG (4.1 BARG) DURING OPERATION.
2.7.
Pressure Correction Factors
It is often necessary to operate RO machines with permeate back pressure. Permeate
back pressure will decrease permeate production. See Table 2.3 (Pressure Correction
Factors) to calculate loss of permeate.
Table 4.
Pressure Correction Factors
Back Pressure
% Loss of Permeate Flow
Pressure Correction Factor
E4/EZ4 E4LE
E4/EZ4
E4LE
10 psig (0.7 barg) 5%
10%
0.95
0.90
20 psig (1.4 barg) 10%
20%
0.90
0.80
30 psig (2.0 barg) 15%
30%
0.80
0.70
