Corrosion And Scale Control - BAC Vertex VRC A-1012N Series Operation & Maintenance Manual

Corrosion and Scale Control

•
To control corrosion and scale, maintain the water chemistry of the recirculating water within the parameters listed in
Table 5. The specific measures required vary from system to system and are dependent on the chemistry of the make-up
water, the metallurgy of the piping and heat transfer devices exposed to the recirculating water, and the temperatures at
which the system will be operating.
•
Bleed/blowdown, the continuous flow of a small portion of the recirculating water to a drain, is used to control the
concentration of dissolved solids. On rare occasions, this may be adequate to control scale and corrosion. More often,
chemical scale and corrosion inhibitors are necessary, which raise the allowable level of dissolved solids without the risk
of scale and corrosion.
•
Keep the chemically treated water within the guidelines given in Table 5. In cases where bleed/blowdown alone is being
employed for corrosion and scale control without chemical treatment your water treatment specialist may recommend
more conservative limits than those shown in Table 5.
Property of Water
pH
Total Suspended
Solids
Total Dissolved Solids
(TDS)
[9]
Conductivity
[9]
Alkalinity as CaCO3
Calcium Hardness as
CaCO3
Chlorides (CL)
Sulfates
Silica
The guidelines in Table 5 refer to the materials used in construction. Different combinations of materials may be used on the same unit.
5
Water chemistry will change with operating temperatures. The recommended guidelines listed in Table 5 refers to water temperature at 95˚F.
6
EVERTOUGH™ Construction units have a TriArmor
7
Galvanized steel units require passivation in order to prevent white rust (refer to "Passivation").
8
The conversion factor used to determine conductivity is 0.625 (TDS = 0.625 x Conductivity).
9
Hardness and alkalinity limits may be exceeded under certain circumstances. Consult your water treatment specialist for recommendations.
10
Vertex™ Evaporative Condenser Operation & Maintenance Manual – Corrosion Protection
Recommended Levels for Various Materials of Construction
Galvanized Thermosetting
Steel Hybrid Polymer
6.5 to 9.0 6.5 to 9.2
[8]
25 ppm 25 ppm
1,500 ppm 2,050 ppm
2,400 3,300
(micromhos/cm) (micromhos/cm)
[10]
500 ppm 600 ppm
[10]
50 to 600 ppm 50 to 750 ppm
250 ppm 300 ppm
250 ppm 350 ppm
150 ppm 150 ppm
Table 5. Quality Guidelines for treated Circulated Water
Corrosion Protection System basin.
®
Type 304
Stainless Steel
6.5 to 9.2
[8] [8]
25 ppm
2,050 ppm
3,300
(micromhos/cm)
[10] [10]
600 ppm
[10] [10]
50 to 750 ppm
300 ppm
350 ppm
150 ppm
[5][6]
TriArmor Corrosion
®
Protection System or
[7]
Type
316 Stainless Steel
6.5 to 9.5
[8]
25 ppm
2,500 ppm
4,000 (micromhos/cm)
[10]
600 ppm
[10]
50 to 750 ppm
750 ppm
750 ppm
150 ppm
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