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11. SYSTEM DESIGN
11-3-6. Water Processing and Water Quality Control
To preserve water quality, use closed water loops for the 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.
•
Remove of foreign objects or impurities within the pipes.
During installation, take extreme care 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 77 ˚F (25 ˚C)
Electric conductivity ( mS/m) 77 ˚F (25 ˚C)
(µ s/cm) 77 ˚F (25 ˚C)
Chloride ion
(mg Cl
Standard
Sulfate ion
(mg SO4
items
Acid consumption
(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.
Do not exceed the maximum of 100L circulating water in the water pipe.
Lower mid-range temperature water
system Water Temp. =< 140 ˚F (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
50 or less
-
/liter)
50 or less
50 or less
2-
/liter)
(pH4.8)
50 or less
50 or less
/liter)
3
70 or less
70 or less
/liter)
3
50 or less
50 or less
/liter)
3
30 or less
30 or less
/liter)
2
1.0 or less
0.3 or less
1.0 or less
1.0 or less
not to be
not to be
/liter)
2-
detected
detected
+
0.3 or less
0.1 or less
/liter)
4
0.25 or less
0.3 or less
0.4 or less
4.0 or less
/liter)
2
–
PWFY-P-NMU-E-BU/PWFY-P-NMU-E-AU (Sept. 2010)
Higher mid-range temperature water
system Water Temp. > 140 ˚F (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]
30 or less
30 or less
30 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
1.0 or less
0.3 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
0.1 or less
0.3 or less
0.4 or less
4.0 or less
–
–
–
Tendency
Corrosive Scale-forming
PWFY-37
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