[
II
Restrictions ]
- 35 -
HWE1517A
GB
2. Notes on pipe corrosion
Water treatment and water quality control
Poor-quality circulating water can cause the water-side heat exchanger to scale up or corrode, reducing heat-
exchange performance. Properly control the quality of the circulating water.
• Removing foreign objects and impurities in the pipes
During installation, keep foreign objects, such as welding and sealant fragments and rust, out of the pipes.
• Water Quality Control
(1)
Poor-quality water can corrode or scale up the heat exchanger. Regular water treatment is recommended.
Water circulation systems using open heat storage tanks are particularly prone to corrosion.
When using an open 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 1 mg/ ℓ.
(2) Water quality standard
(3)
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.
(4)
When replacing an air conditioner (including when only the heat exchanger is replaced), first analyze the water
quality and check for possible corrosion.
Corrosion can occur in water systems in which there has been no signs of corrosion. If the water quality level
has dropped, adjust the water quality before replacing the unit.
(5) Suspended solids in the water
Sand, pebbles, suspended solids, and corrosion products in water can damage the heating surface of the heat
exchanger and cause corrosion. Install a good quality strainer (60 mesh or better) at the inlet of the unit to filter
out suspended solids.
(6) Connecting pipes made from different materials
If different types of metals are placed in direct contact with each other, the contact surface will corrode.
Install an insulating material between pipes that are made of different materials to keep them out of direct
contact with each other.
Reference: Guideline of Water Quality for Refrigeration and Air Conditioning Equipment. (JRA GL02E-1994)
Items
Higher mid-range temperature water system
Water Temp. > 60ºC
Make-up water criteria
(with secondary side control enabled)
Water Temp. > 60ºC
Tendency
Recirculating water
Recirculating water
Corrosive
Scale-
forming
Standard
items
pH (25°C)
0
.
8
~
5
.
6
0
.
8
~
5
.
6
Electric conductivity
(mS/m) (25
s
s
e
l
r
o
0
3
s
s
e
l
r
o
0
3
)
°C
(μs/cm) (25
]
s
s
e
l
r
o
0
0
3
[
]
s
s
e
l
r
o
0
0
3
[
)
°C
Chloride ion
(mg Cl
-
/ℓ)
s
s
e
l
r
o
0
3
s
s
e
l
r
o
0
3
Sulfate ion
(mg SO4
2-
/ℓ)
s
s
e
l
r
o
0
3
s
s
e
l
r
o
0
3
Acid consumption
s
s
e
l
r
o
0
5
s
s
e
l
r
o
0
5
(pH4.8) (mg CaCO
3
/ℓ)
Calcium hardness
(mg CaCO
3
/ℓ)
6.5 ≤ pH ≤ 7.5 : 90 or less
7.5 ≤ pH ≤ 8.0 : 50 or less
250 or less
Ionic silica
(mg SiO
2
/ℓ)
s
s
e
l
r
o
0
3
s
s
e
l
r
o
0
3
Reference
items
/
e
F
g
m
(
n
o
r
I
ℓ
s
s
e
l
r
o
3
.
0
s
s
e
l
r
o
3
.
0
)
Copper
(mg Cu/ℓ
s
s
e
l
r
o
1
.
0
s
s
e
l
r
o
1
.
0
)
Sulfide ion
(mg S
2-
/ℓ)
d
e
t
c
e
t
e
d
e
b
o
t
t
o
N
d
e
t
c
e
t
e
d
e
b
o
t
t
o
N
Ammonium ion
(mg NH
4
+
/ℓ)
s
s
e
l
r
o
1
.
0
s
s
e
l
r
o
1
.
0
Residual chlorine
(mg Cl/ ℓ
s
s
e
l
r
o
1
.
0
s
s
e
l
r
o
1
.
0
)
Free carbon dioxide
(mg CO
2
/ℓ)
s
s
e
l
r
o
0
.
0
1
s
s
e
l
r
o
0
.
0
1
0000001906.book 35 ページ ２０１８年７月１９日 木曜日 午前７時２２分
Summary of Contents for QAHV-N560YA-HPB
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Page 175: ... X Attachments 168 HWE1517A GB 0000001906 book 168 ページ ２０１８年７月１９日 木曜日 午前７時２２分 ...
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