SPX Cooling Technologies MH Fluid Cooler User Manual page 21

Note
maintenance
The structure and coil of your fluid cooler consists primarily of
galvanized steel, therefore your water treatment program must be
compatible with zinc. In working with your water treatment supplier,
it is important that you recognize the potential effects on zinc of
the specific treatment program you choose.
Blowdown:
A fluid cooler cools water by continuously causing a portion of it to evaporate.
Although the water lost by evaporation is replenished by the makeup system,
it exits the fluid cooler as pure water—leaving behind its burden of dissolved
solids to concentrate in the remaining water. Given no means of control, this
increasing concentration of contaminants can reach a very high level.
In order to achieve water quality which is acceptable to the fluid cooler, the
selected water treatment company must work from a relatively constant level
of concentrations. This stabilization of contaminant concentrations is usually
accomplished by blowdown, which is the constant discharge of a portion of
the circulating water to waste. As a rule, acceptable levels on which to base
a treatment schedule will be in the range of 2-4 concentrations. The following
table shows the minimum amount of blowdown (percent of flow) required to
maintain different concentrations with various cooling ranges*:
C o o n i l g R a n g e
1 5 .
3°C 7 .
6°C 1 5 .
8°C 2 3 .
11°C 3 1 .
14°C 3 9 .
M u t l p i e i l s r a e r b a
* Range = Difference between hot water temperature and cold water temperature.
EXAMPLE: 160 m 3 /hr circulating rate, 10°C cooling range. To maintain 4
concentrations, the required blowdown is 0.458% or .00458 times 160 m
which is .73 m 3 /hr.
If fluid cooler is operated at 4 concentrations, circulating water will contain
four times as much dissolved solid as the makeup water, assuming none of
the solids form scale or are otherwise removed from the system.
N u m b r e f o C o
X 2 0 . X 2 5 . X 3 0 .
3 . 8 2 . 5 1 . 8
7 . 8 5 . 1 3 . 8
1 1 . 8 7 . 8 5 . 8
1 5 . 8 1 0 . 5 7 . 8
1 9 . 8 1 3 . 2 9 . 8
s e d o n r d t f i f o 0 0 . 2 % f o h t e i c
n c e n r t t a o i n s
X 4 0 . X 5 0 . X 6 0 . X
1 . 1 0 . 8 0 . 6
2 . 5 1 . 8 1 . 4
3 . 8 2 . 8 2 . 2
5 . 1 3 . 8 3 . 0
6 . 4 4 . 8 3 . 8
c r l u t a n i g w a e t r r t a . e
3 /hr,
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