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Water Quality Management
A brazing plate water heat exchanger is built in a way that does not allow dismantling and cleaning or
component replacement.
Care must be exercised concerning the quality of the water used in a water heat exchanger in order to
prevent corrosion and scaling.
The minimum requirements for the quality of water used in a plate water heat exchanger are those
stipulated by the "Water Quality Guidelines for Cooling and Air Conditioning Devices"
(JRA-GL-02-1994) of The Japan Refrigeration and Air Conditioning Industry Association.
When using a rust inhibitor, scale inhibitor, or any other type of agent, make sure that it is a type that will
not corrode cast iron, stainless steel, copper, bronze, rubber and gasket.
Water quality standard values of chilled (warm) water and supplementary water
(1) (6)
Item
Circulation
water
pH (25ºC）
6.5 to 8.2
Electrical conductivity
(mS/m)(25°C）
80 or less
(1)
{μS/cm} (25°C ）
{800 or less} {300 or less} {400 or less} {400 or less} {300 or less}
-
Chloride ion (mgCl
/l)
200 or less
2-
Sulphate ion (mgSO
/l)
200 or less
4
Acid consumption (pH4.8)
(mgCaCO
/l)
100 or less
3
Total hardness (mgCaCO
/l)
200 or less
3
Calcium hardness
(mgCaCO
/l)
150 or less
3
Ionic silica (mgSiO
/l)
50 or less
2
Iron (mgFe/l)
1.0 or less
Copper (mgCu/l)
0.3 or less
2-
Chloride ion (mgS
/l)
Undetectable
+
Ammonium ion (mgNH
/l)
1.0 or less
4
Residual chlorine (mgCl/l)
0.3 or less
Free carbon (mgCO
/l)
4.0 or less
2
Stability index
6.0 to 7.0
Note (1) Item names, term definitions, and units are in accordance with JIS K 0101. Units and values in brackets ({ }) are conventional
units provided for reference.
(2) A circle (○) in a cell indicates a factor related to corrosion or scaling.
(3) High temperatures (40°C or higher) generally result in a striking increase in corrosion. In the case of ferrous metal materials
in particular, if such material will come into direct contact with the water it is best to perform effective corrosion protection
measures, such as the addition of an anti-corrosion agents, deterioration, etc.
(4) Cooling water systems that uses a sealed cooling tower, closed-circuit circulation water and other supplementary water
depend on warm water system water quality standards, while sprinkler water and other supplementary water depend on
circulative water system water quality standards.
(5) Supply and supplementary source water means tap water (water supply), industrial water, or ground water. Purified water,
grey water, and softened water are not included.
(6) The above 15 items show representative factors of corrosion and scale impairment.
※ For details, refer to the "Water Quality Guidelines for Cooling and Air Conditioning Devices" (JRA-GL-02-1994) of The Japan
Refrigeration and Air Conditioning Industry Association.
(4)
Cooling water system
Chilled water system
Once-
Circulation
through
Once-
Circulation
Make up
through
[20°C or
water
water
lower]
6.0 to 8.0
6.8 to 8.0
6.8 to 8.0
30 or less
40 or less
40 or less
50 or less
50 or less
50 or less
50 or less
50 or less
50 or less
50 or less
50 or less
50 or less
70 or less
70 or less
70 or less
50 or less
50 or less
50 or less
30 or less
30 or less
30 or less
0.3 or less
1.0 or less
1.0 or less
0.1 or less
1.0 or less
1.0 or less
Undetectable
Undetectable
Undetectable
0.1 or less
1.0 or less
1.0 or less
0.3 or less
0.3 or less
0.3 or less
4.0 or less
4.0 or less
4.0 or less
-
-
Low-grade medium temperature
water system
Circulation water
Make up
[Greater than 20°C,
water
less than 60°C]
6.8 to 8.0
7.0 to 8.0
30 or less
30 or less
{300 or less}
50 or less
50 or less
50 or less
50 or less
50 or less
50 or less
70 or less
70 or less
50 or less
50 or less
30 or less
30 or less
0.3 or less
1.0 or less
0.1 or less
1.0 or less
Undetectable
Undetectable
0.1 or less
0.3 or less
0.3 or less
0.25 or less
4.0 or less
0.4 or less
-
-
-
- 77 -
(3)
Warm water system
High-grade medium temperature
water system
Circulation water
Make up
Make up
[Greater than 60°C,
water
water
less than 90°C]
7.0 to 8.0
7.0 to 8.0
7.0 to 8.0
30 or less
30 or less
30 or less
{300 or less}
{300 or less}
{300 or less}
50 or less
30 or less
30 or less
50 or less
30 or less
30 or less
50 or less
50 or less
50 or less
70 or less
70 or less
70 or less
50 or less
50 or less
50 or less
30 or less
30 or less
30 or less
0.3 or less
1.0 or less
0.3 or less
0.1 or less
1.0 or less
0.1 or less
Undetectable
Undetectable
Undetectable
0.1 or less
0.1 or less
0.1 or less
0.3 or less
0.1 or less
0.3 or less
4.0 or less
0.4 or less
4.0 or less
-
-
(2)
Tendency
Scale
Corrosion
formation
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
-
○
○
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