Quality guidelines for circulating and
additive water
Circulating water Additive water
1)
Apperance Colourless, clear,
no sediments
Colourless, clear,
no sediments
pH value
2)
7.5 - 8.5 -
Total salt content < 2,500 ppm < 1,250 ppm
Conductivity < 3,000 µS/cm -
Calcium > 20 ppm > 10 ppm
Carbonate hard-
ness without hard-
ness stabilation
< 4 ûdH
< 71 ppm
CaCO
3
< 2 ûdH
< 35 ppm
CaCO
3
Carbonate hard-
ness with hard-
ness stabilation
< 20 ûdH
< 356 ppm
CaCO
3
< 10 ûdH
< 178 ppm
CaCO
3
Chloride < 200 ppm < 100 ppm
Sulphate < 300 ppm < 150 ppm
KMnO
4
< 100 g/m
3
-
Germ number < 10,000 /ml -
Table 1: Quality guidelines for circulating and additive water
1)
Minimum requirements in the case of contration
factor 2. At a higher concentration the values are
accordingly lower.
2)
When using chemical additives, the pH values
may be located outside the specified range.
Monitoring of the water quality
pH Value, water hardness and conductivity of the
circulating water should, at least, be measured
every 2 weeks. Based on the conductivity, it can be
checked whether the prescribed concentration fac-
tor is kept. Regular checks must include the values
stated in
Table 1
.
Utilisation of biocides
Intensive venting of the water in the cooling tower
and insulation will, above all, during the warm sea-
son, cause algeas and microorganisms, which clog
the cooling system, support corrosion and clearly
reduce the cooling efficiency.
Growth by algeas, shells and bacteria colonies
must, therefore, be eliminated by vaccination with
chlorine or effective biocides.
The selection and application of biocides depends
on the occurring microorganisms. Close coopera-
tion with the manufacturer, resp. supplier, would be
recommendable as they dispose of suitable test
processes for micro organism detection as well as
the necessary experience.
Environmental protection, safety
The locally applicable environmental requirements
are, in cooling tower operation, to be taken into
consideration for the discharge of blow-down water
and disposal of the substances (hardness stabilis-
ers, biocides, corrosion inhibitors, dispersants) used
for cooling water treatment.
When using chemical additives, the safety regula-
tions of the manufactures must, by all means, be
observed.
MAN Diesel & Turbo
B 13 00 0
Quality of raw-water in cooling tower operation
(additive and circulating water)
1699250-5.0
Page 2 (2)
L28/32S, L27/38S, L23/30S, L21/31S, L16/24S, V28/32S, L16/24, L21/31,
L23/30H, L27/38, L28/32H
2008.10.27
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