Installation guide
RO-MAN REVERSE OSMOSIS SYSTEM INSTALLATION GUIDE
14
P
ERFORMANCE OF THE REVERSE OSMOSIS MEMBRANE ELEMENT IS AFFECTED BY TWO KEY FACTORS;
TEMPERATURE OF THE FEED WATER AND THE NET DRIVING PRESSURE ACROSS THE ELEMENT
. THESE TWO
FACTORS MUST BE TAKEN INTO ACCOUNT BEFORE COMPARING OR EVALUATING THE PERFORMANCE OF A
MEMBRANE ELEMENT OR A REVERSE OSMOSIS SYSTEM
.
T
HE WATER TEMPERATURE IS ONE OF THE KEY FACTORS IN THE PE5RFORMANCE OF THE REVERSE OSMOSIS
MEMBRANE ELEMENT
. THE HIGHER THE TEMPERATURE, THE MORE THE PRODUCT FLOW AND VICE VERSA. ALL
REVERSE OSMOSIS MEMBRANE ELEMENTS AND SYSTEMS ARE RATED AT
77º FAHRENHEIT (25ºCELSIUS). TO
FIND THE MEMBRANE PERMEATE RATE AT A DIFFERENT TEMPERATURE
, FOLLOW THESE STEPS:
F
IND THE TEMPERATURE CORRECTION FACTOR (TCF) FROM THE TABLE BELOW.
D
IVIDE THE RATED PERMEATE FLOW AT 77 DEGREES FAHRENHEIT BY THE TEMPERATURE CORRECTION
FACTOR
. THE RESULT IS THE PERMEATE FLOW AT THE DESIRED TEMPERATURE.
Feed Water
Temperature
ºC ºF
Correction Factor
5 41.0 2.58
6 42.8 2.38
7 44.6 2.22
8 46.4 2.11
9 48.2 2.00
10 50.0 1.89
11 51.8 1.78
12 53.6 1.68
13 55.4 1.61
14 57.2 1.54
15 59.0 1.47
16 60.8 1.39
17 62.6 1.34
Feed Water
Temperature
ºC ºF
Correction Factor
18 64.4 1.29
19 66.2 1.24
20 68.0 1.19
21 69.8 1.15
22 71.6 1.11
23 73.4 1.09
24 75.2 1.04
25 77.0 1.00
26 78.8 0.97
27 80.6 0.94
28 82.4 0.91
29 84.2 0.88
30 86.0 0.85
EXAMPLE
QUESTION
F
OR A THIN-FILM MEMBRANE PERMEATE RATE AT 77 DEGREES FAHRENHEIT = 100 GALLONS/DAY. WHAT IS
THE PERMEATE RATE AT
59 DEGREES FAHRENHEIT?
ANSWER
T
EMPERATURE CORRECTION FACTOR (FROM TABLE) = 1.47
P
ERMEATE FLOW AT 59 DEGREES FAHRENHEIT = 100÷1.47 = 68.03 GALLONS (US)/DAY
Net Pressure Correction
P
ERFORMANCE OF THE REVERSE OSMOSIS MEMBRANE ELEMENT IS AFFECTED BY TWO KEY FACTORS;
TEMPERATURE OF THE FEED WATER AND THE NET DRIVING PRESSURE ACROSS THE ELEMENT
. THESE TWO
FACTORS MUST BE TAKEN INTO ACCOUNT BEFORE COMPARING OR EVALUATING THE PERFORMANCE OF A
MEMBRANE ELEMENT OR A REVERSE OSMOSIS SYSTEM
.
T
HE HIGHER THE NET PRESSURE ON A MEMBRANE ELEMENT, THE HIGHER THE PERMEATE RATE. THE OSMOTIC
PRESSURE OF WATER CAN BE CALCULATED ROUGHLY BY THE FOLLOWING RULE OF THUMB
:
O
SMOTIC PRESSURE (PSI) = TOTAL DISSOLVED SOLIDS (TDS) ÷ 100
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