York YHAU-CL Series, Установка, эксплуатация и обслуживание

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JOHNSON CONTROLS
147
SECTION 7 – MAINTENANCE
FORM 155.30-ICOM2.EN.UL
ISSUE DATE: 12/21/2018
7
TABLE 33 - TENDENCY OF GENERATION OF SCALES AND CORROSION BY QUALITY OF COOLING
WATER
QUALITY OF COOLING
WATER
GENERAL TENDENCY
SCALE AND ITS COLOR CORROSION AND ITS COLOR
Factors of
Water Quality
Low water PH
Hard scales are generated
and iron bacteria propagate.
Severe corrosion of
iron and copper.
Dark brown
~ Pale
greenish
blue
High PH water
Calcium carbonate scales
are generated easily.
Pale
yellow
──
Water contains many
calcium ions (Ca
2+
) and
magnesium ions(Mg
2+
)
Sulfuric ion SO
4
2-
, silica SiO
2
and 2 carbonate ion CO
3
2-
combine together to generate
hard scales.
Pale
yellow
──
Water contains many
chlorine ions (Cl
-
)
──
Iron and copper
tubes are corroded.
Water contains many
sulfuric ions (SO
4
2-
) and
silica (SiO
2
)
Calcium sulfide (CaSO
4
) and
calcium silicate (CaSiO
3
)
combine together to generate
hard scales.
Gray
SO
4
2-
corrodes
copper tubes.
Greenish
Blue
Water contains many iron
(Ferrous ion (Fe
2+
),ferric
ion (Fe
3+
))
Fe
3+
becomes ferric
hydroxide (Fe(OH)
3
) to make
red water and sets red rust
of ferric dioxide (Fe
2
O
3
). Iron
bacteria propagate.
Reddish
brown-
Black
Fe
3+
corrodes iron
and copper tubes.
Reddish
brown-
Black
Environmental
Factors
Water smells bad
(Contains compounds of
sulfur, hydrogen sulfide
(H
2
S), ammonium ion
(NH
4
+
), methane, etc.)
Scales are generated easily,
and slime is generated.
Greenish
Blue –
Dark
brown
H
2
S and NH
4
+
corrodes copper
tubes severely.
Black –
Greenish
blue
Water contains organic
matter (High COD and
BOD)
Scales are generated easily,
and slime is generated.
──
Exhaust gases (Sulfurous
acid gas (SO
2
), nitrogen
oxide (NO
2
), hydrogen
chloride (HCl), ammonia
(NH
3
), and so on) mixed in
water in cooling tower
If organic nitrogen and
inorganic nitrogen are
contained, algae propagate.
SO
2
becomes SO
4
2-
and
combines with Ca
2+
and Mg
2+
to generate scales.
Algae:
Green
Pale
yellow
Exhaust gas from
automobiles,
factories, sewage
plants, ammonia
refrigerating
machine, and so on,
lower or heighten PH
number. As SO
4
2-
,
Cl
-
and NH
4
+
are
increased, tubes are
corroded and pitted
rapidly.
Solid matter (Mud, sand,
fibers, dust, insects,and
so on) in water in cooling
tower
Scales are generated easily.
Solid matters set. Slime is
generated.
────
Sea wind (District by sea) Scales are generated easily.
Tubes are corroded
severely.
Reddish
brown-
Black