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(8) Water processing and water quality control
To preserve water quality, use the closed type of cooling tower for unit. When the circulating water quality is poor, the
water heat exchanger can develop scales, leading to a reduction in heat-exchange power and possible corrosion of the
heat exchanger. Please pay careful attention to water processing and water quality control when installing the water
circulation system.
•
Removal of foreign objects or impurities within the pipes.
During installation, be careful that foreign objects, such as welding fragments, sealant particles, or rust, do not enter
the pipes.
•
Water Quality Processing
a) Depending on the quality of the cold-temperature water used in the air-conditioner, the copper piping of the heat
exchanger may become corroded. We recommend regular water quality processing.
Cold water circulation systems using open heat storage tanks are particularly prone to corrosion.
When using an open-type heat storage tank, install a water-to-water heat exchanger, and use a closed-loop
circuit on the air conditioner side. If a water supply tank is installed, keep contact with air to a minimum, and
keep the level of dissolved oxygen in the water no higher than 1mg/liter.
b) Water quality standard
Reference : Guideline of Water Quality for Refrigeration and Air Conditioning Equipment. (JRA GL02E-1994)
c) Please consult with a water quality control specialist about water quality control methods and water quality
calculations before using anti-corrosive solutions for water quality management.
d) When replacing a previously installed air conditioning device (even when only the heat exchanger is being
replaced), first conduct a water quality analysis and check for possible corrosion.
Corrosion can occur in cold-water systems even if there has been no prior signs of corrosion.
If the water quality level has dropped, please adjust water quality sufficiently before replacing the unit.
Refer to the below graph for the maximum amount of circulating water in the water pipe. Make sure that this
amount does not exceed.
[
Fig. IV. 3. (8).1] Maximum circulating water
pH (25 ˚C)
Electric conductivity (mS/m) (25 ˚C)
(µ s/cm) (25 ˚C)
Chloride ion
(mg Cl
-
/liter)
Sulfate ion
(mg SO4
2-
/liter)
Acid consumption (pH4.8)
(mg CaCO
3
/liter)
Total hardness (mg CaCO
3
/liter)
Calcium hardness (mg CaCO
3
/liter)
Ionic silica
(mg SiO
2
/liter)
Iron
(mg Fe/liter)
Copper
(mg Cu/liter)
Sulfide ion
(mg S
2-
/liter)
Ammonium ion
(mg NH
4
+
/liter)
Residual chlorine
(mg Cl/liter)
Free carbon dioxide (mg CO
2
/liter)
Ryzner stability index
Standard
items
Refer-
ence
items
Items
Lower mid-range temperature water system
Water Temp.
=<
60 ˚C
7.0 ~ 8.0
30 or less
[300 or less]
50 or less
50 or less
50 or less
70 or less
50 or less
30 or less
1.0 or less
1.0 or less
not to be
detected
0.3 or less
0.25 or less
0.4 or less
–
7.0 ~ 8.0
30 or less
[300 or less]
50 or less
50 or less
50 or less
70 or less
50 or less
30 or less
0.3 or less
1.0 or less
not to be
detected
0.1 or less
0.3 or less
4.0 or less
–
Tendency
Recirculating water
Make-up water
Corrosive Scale-forming
Higher mid-range temperature water system
Water Temp. >
60 ˚C
Recirculating water
Make-up water
7.0 ~ 8.0
30 or less
[300 or less]
30 or less
30 or less
50 or less
70 or less
50 or less
30 or less
1.0 or less
1.0 or less
not to be
detected
0.1 or less
0.1 or less
0.4 or less
–
7.0 ~ 8.0
30 or less
[300 or less]
30 or less
30 or less
50 or less
70 or less
50 or less
30 or less
0.3 or less
1.0 or less
not to be
detected
0.1 or less
0.3 or less
4.0 or less
–
0
100
200
300
400
500
0
10
20
30
40
50
60
70
Total hardness [mg/L]
Water volume limitation [L
]
0
500
1000
1500
2000
2500
3000
0
10
20
30
40
50
60
70
Total hardness [mg/L]
Water volume limitation [L
]
PWFY-P100VM-E-BU
Condition: Water outlet temp. 70°C
Condition: Water outlet temp. 45°C
PWFY-P100/200VM-E1/E2-AU
Available water volume area
Available water volume area
