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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
Items
pH (25 ˚C)
Electric conductivity (mS/m) (25 ˚C)
(µ s/cm) (25 ˚C)
Chloride ion
(mg Cl
Sulfate ion
(mg SO4
Standard
Acid consumption (pH4.8)
items
(mg CaCO
Total hardness
(mg CaCO
Calcium hardness (mg CaCO
Ionic silica
(mg SiO
Refer-
Iron
(mg Fe/liter)
ence
Copper
(mg Cu/liter)
items
Sulfide ion
(mg S
Ammonium ion
(mg NH
Residual chlorine
(mg Cl/liter)
Free carbon dioxide (mg CO
Ryzner stability index
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
PWFY-P100VM-E-BU
500
400
300
200
Available water volume area
100
0
0
10
20
Total hardness [mg/L]
Condition: Water outlet temp. 70°C
Lower mid-range temperature water system
Water Temp. =< 60 ˚C
Recirculating water
7.0 ~ 8.0
30 or less
[300 or less]
-
/liter)
50 or less
2-
/liter)
50 or less
50 or less
/liter)
3
/liter)
70 or less
3
/liter)
50 or less
3
/liter)
30 or less
2
1.0 or less
1.0 or less
not to be
2-
/liter)
detected
+
/liter)
0.3 or less
4
0.25 or less
/liter)
0.4 or less
2
–
30
40
50
60
Higher mid-range temperature water system
Water Temp. > 60 ˚C
Recirculating water
Make-up water
7.0 ~ 8.0
7.0 ~ 8.0
30 or less
30 or less
[300 or less]
[300 or less]
50 or less
30 or less
50 or less
30 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
1.0 or less
1.0 or less
not to be
not to be
detected
detected
0.1 or less
0.1 or less
0.3 or less
0.1 or less
4.0 or less
0.4 or less
–
–
PWFY-P100/200VM-E1/E2-AU
3000
2500
2000
1500
1000
Available water volume area
500
0
70
0
10
Condition: Water outlet temp. 45°C
- 63 -
Corrosive Scale-forming
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
0.3 or less
1.0 or less
not to be
detected
0.1 or less
0.3 or less
4.0 or less
–
20
30
40
50
Total hardness [mg/L]
Tendency
60
70
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