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5-5
Water quality standard for chilled water
Water quality standard for hot water
(1) The item appellation and its definition and the unit belong to JIS K 0101.
(2) The “yes” in the chart show the factor relevant to corrosion or scale genesis.
(3) When high temperature (over 40
o
C);generally, using corrosive steel, materials which have no
protective coating against water, anticorrosive measure shall be done such as adding corrosion
prevention material, degasser and etc.
(4) Under the Cooling water system with hermetically-closed cooling tower; the closed-circuit
circulating water and its Makeup water are based on Hot water standard, spreading water and
its Makeup water are based on circulating Cooling water system.
(5) Supplied / replenished water needs to be tap water or industrial water or groundwater.
Deionized water, regeneration treated water and softening treated water are excluded.
(6) Upper15 items are shown as a typical factor for corrosion and/or scale genesis.
[Note 1] Each item of the standard values may cause a failure due to corrosion or scale and if any
item deviates from the standard value, it is assumed that corrosion or scale tends to be
caused, therefore, these should be periodically managed.
[Note 2] As the range of the water quality which may become usable if the water is processed
differs depending on the chemicals to be used, it is not given here. It is desirable to set
the appropriate water quality management values under the guidance of a water
processing specialist and periodically manage the water quality.
Circulation
T=<20C(68F)
pH(at 25C(77F))
6.5 - 8.0
6.0 - 8.0
Yes
Yes
Electrical conductivity 25C
ms/m
40 or less
30 or less
Yes
Yes
Chloride ion
mgCl
-
/l
50 or less
50 or less
Yes
Sulfuric acid ion
mgSO
4
2-
/l
50 or less
50 or less
Yes
Acid consumption pH 4.8
mgCaCO
3
/l
50 or less
50 or less
Yes
Total hardness
mgCaCO
3
/l
70 or less
70 or less
Yes
Calcium hardness
mgCaCO
3
/l
50 or less
50 or less
Yes
Ion silica
mgSiO
2
/l
30 or less
30 or less
Yes
Iron
mgFe/l
1.0 or less
0.3 or less
Yes
Yes
Copper
mgCu/l
1.0 or less
0.1 or less
Yes
Sulfide ion
mgS
2-
/l
No detected
No detected
Yes
Ammonium ion
mgNH
4
+
/l
1.0 or less
0.1 or less
Yes
Residual chlorine
mgCl/l
0.3 or less
0.3 or less
Yes
Free carbon dioxide
mgCO
2
/l
4.0 or less
4.0 or less
Yes
Ryzner stability index
RSI
***
***
Yes
Yes
S
tanda
rd
R
e
fe
rence
Tendency
Make up
Chilled water line
Corrosion
Scale
Circulation
Make up
Circulation
Make up
pH(at 25C(77F))
7.0 - 8.0
7.0 - 8.0
7.0 - 8.0
7.0 - 8.0
Yes
Electrical conductivity 25C
ms/m
30 or less
30 or less
30 or less
30 or less
Yes
Chloride ion
mgCl
-
/l
50 or less
50 or less
30 or less
30 or less
Yes
Sulfuric acid ion
mgSO
4
2-
/l
50 or less
50 or less
30 or less
30 or less
Yes
Acid consumption pH 4.8
mgCaCO
3
/l
50 or less
50 or less
50 or less
50 or less
Total hardness
mgCaCO
3
/l
70 or less
70 or less
70 or less
70 or less
Calcium hardness
mgCaCO
3
/l
50 or less
50 or less
50 or less
50 or less
Ion silica
mgSiO
2
/l
30 or less
30 or less
30 or less
30 or less
Iron
mgFe/l
1.0 or less
0.3 or less
1.0 or less
0.3 or less
Yes
Copper
mgCu/l
1.0 or less
0.1 or less
1.0 or less
0.1 or less
Yes
Sulfide ion
mgS
2-
/l
No detected
No detected
No detected
No detected
Yes
Ammonium ion
mgNH
4
+
/l
0.3 or less
0.1 or less
0.1 or less
0.1 or less
Yes
Residual chlorine
mgCl/l
0.25 or less
0.3 or less
0.1 or less
0.3 or less
Yes
Free carbon dioxide
mgCO
2
/l
0.4 or less
4.0 or less
0.4 or less
4.0 or less
Yes
Ryzner stability index
RSI
***
***
***
***
Yes
Hot water line
60C(140F)=<T<90C(194F)
Yes
Yes
Yes
Yes
Yes
S
ta
ndar
d
Re
fe
re
n
c
e
20C(68F)=<T<60C(140F)
Yes
Tendency
Scale
Corrosion
Yes
Yes