Table 38 - Tendency Of Generation Of Scales And Corrosion By Quality Of Cooling Water - York EX Series Installation, Operation & Maintenance Instructions Manual

SECTION 7 – MAINTENANCE
TABLE 38 - TENDENCY OF GENERATION OF SCALES AND CORROSION BY QUALITY OF COOLING
WATER
QUALITY OF COOLING
Water of low PH number
Water of high PH number
Water contains many
calcium ions (Ca
magnesium ions(Mg
Factors of
Water contains many
Water Quality
chlorine ion (Cl
Water contains many
sulfuric ions (SO
silica (SiO
Water contains many iron
(Ferrous ion (Fe
ion (Fe ))
3+
Water smells bad
(Contains compounds of
sulfur, hydrogen sulfide
(H S), ammonium ion
2
(NH ), methane, etc.)
4+
Water contains organic
matters (High COD and
BOD)
Exhaust gases (Sulfurous
Environmental acid gas (SO
Factors oxide (NO
chloride (HCl), ammonia
(NH ), etc.) mixed in water
3
in cooling tower
Solid matter (Mud, sand,
fibers, dust, insects, etc.)
in water in cooling tower
Sea wind (District by sea)
152
WATER
SCALE AND ITS COLOR
Hard scales are generated
and iron bacteria propagate
Calcium carbonate scales
are generated easily.
Sulfuric ion SO
and 2 carbonate ion CO
) and
2+
combine together to generate
)
2+
hard scales.
──
)
-
Calcium sulfide (CaSO
calcium silicate (CaSiO
) and
2-
combine together to generate
4
)
hard scales.
2
Fe becomes ferric
3+
hydroxide (Fe(OH)
red water and sets red rust
),ferric
2+
of ferric dioxide (Fe
Iron bacteria propagate
remarkably.
Scales are generated easily,
and slime is generated.
Scales are generated easily,
and slime is generated.
If organic nitrogen and
), nitrogen inorganic nitrogen are
2
), hydrogen contained, algae propagate.
2
SO becomes SO
2
combines with Ca
to generate scales.
Scales are generated easily.
Solid matters set. Slime is
generated.
Scales are generated easily.
GENERAL TENDENCY
Pale
yellow
, silica SiO
2-
4 2
Pale
2-
3
yellow
) and
4
)
Gray
3
) to make
Reddish
3
brown-
O ).
Black
2 3
Greenish
Blue –
Dark
brown
Algae:
Green
and Pale
2-
4
and Mg yellow
2+ 2+
FORM 155.32-ICOM1.EN.GB
ISSUE DATE: 10/13/2017
CORROSION AND ITS COLOR
Dark brown
Bad corrosion of iron ~ Pale
and copper greenish
blue
──
──
Iron and copper
tubes are corroded
badly.
SO corrodes Greenish
2-
4
copper tubes badly. Blue
Reddish
Fe corrodes iron
3+
brown-
and copper tubes
Black
H S and NH Black –
+
2 4
corrodes copper Greenish
tubes badly. blue
──
Exhaust gas from
automobiles,
factories, sewage
plants, ammonia
refrigerating
machine, etc. lower
or heighten PH
number. As SO ,
2-
4
Cl and NH are
- +
4
increased, tubes are
corroded and pitted
very quickly.
────
Reddish
Tubes are corroded
brown-
badly.
Black
JOHNSON CONTROLS