140.925-IOM (APR 2019)
Page 29
XLP3 EVAPORATIVE CONDENSERS
MAINTENANCE
Gray Water and Reclaimed Water
The use of water reclaimed from another process as a source
of makeup water for evaporative cooling equipment can be
considered as long as the resultant recirculating water chemistry
conforms to the parameters noted in Table 5. It should be noted
that using water reclaimed form other processes may increase
the potential of corrosion, microbiological fouling, or scale for-
mation. Gray water or reclaimed water should be avoided unless
all the associated risks are understood and documented as part
of the site specific treatment plan.
NOTICE
1. Galvanized steel units require passivation in order to
prevent white rust (refer to “Passivation”).
2. Hardness and alkalinity limits may be exceeded under
certain circumstances. Consult your water treatment
specialist for recommendations.
3. The conversion factor used to determine conductivity
is 0.625 (TDS = 0.625 x Conductivity).
4. DuraTest™ Construction units have a TripleGuard®
Corrosion Protection System basin.
5. The guidelines above refer to the materials used in
construction. Different combinations of materials may be
used on the same unit.
6.
Water chemistry will change with operating
temperatures. The recommended guidelines listed in
Table 2 refers to water temperature at 95˚F.
Chemical Treatment Requirements
Chemical treatment programs must meet the following require-
ments:
• The chemicals must be compatible with the unit materials
of construction as well as other materials used in the
system (pipe, heat exchanger, etc.).
• Frick discourages acid dosing as means of scale control
except for open circuit cooling towers with remote sump
applications or towers constructed from stainless steel.
This should be done at a point in the system where total
mixing and dilution occur before reaching the evaporative
Table 5 — Quality Guidelines for Treated Circulated Water
Property of Water
Recommended Levels for Various Materials of Construction
Galvanized
Steel
Thermosetting
Hybrid Polymer
Type 304
Stainless Steel
TripleGuard®
Corrosion Protection
System or Type 316
Stainless Steel
pH
6.5 to 9.0[1]
6.5 to 9.2[1]
6.5 to 9.2[1]
6.5 to 9.5[1]
Total Suspended Solids
25 ppm
25 ppm
25 ppm
25 ppm
Total Dissolved Solids (TDS)
1,500 ppm
2,050 ppm
2,050 ppm
2,500 ppm
Conductivity
2,400
(micromhos/cm)
3,300
(micromhos/cm)
3,300
(micromhos/cm)
4,000
(micromhos/cm)
Alkalinity as CaCO3
500 ppm[2]
600 ppm[2]
600 ppm[2]
600 ppm[2]
Calcium Hardness as CaCO3
50 to 600 ppm[2]
50 to 750 ppm[2]
50 to 750 ppm[2]
50 to 750 ppm[2]
Chlorides (CL)
250 ppm
300 ppm
300 ppm
750 ppm
Sulfates
250 ppm
350 ppm
350 ppm
750 ppm
Silica
150 ppm
150 ppm
150 ppm
150 ppm
cooling equipment. The preferred injection point for
chemical scale and corrosion inhibitors is on the discharge
side of the system circulating pump(s). These chemicals
should not be batch fed directly into the unit’s cold water
basin or water distribution system, as this can severely
damage areas directly contacted.
• When chlorine is added to the system, free residual
chlorine should not exceed 1 ppm, except as noted in start-
up and shutdown section on Page 15. Exceeding this limit
may accelerate corrosion.
Passivation
When new systems are first commissioned, special measures
should be taken to ensure that galvanized steel surfaces are
properly passivated to provide maximum protection from corro-
sion. Passivation is the formation of a protective, passive, oxide
layer on galvanized steel surfaces. To ensure the galvanized steel
surfaces are passivated, the pH of circulating water should be
kept between 6.5 and 8.2 and calcium hardness between 50 and
600 ppm (as CaCO
3
) for four to eight weeks after start-up, or until
new zinc surfaces turn dull gray in color. If white deposits form
on galvanized steel surfaces after the pH is returned to normal
service levels, it may be necessary to repeat the passivation
process. In case the pH can’t be kept below 8.2, a secondary
approach is to conduct a chemical passivation using inorganic
phosphate or film-forming passivation agents. Consult your water
treatment specialist for specific recommendation.
NOTICE
Stainless steel cold water basins and basins protected by
the TripleGuard® Corrosion Protection System or
thermosetting hybrid polymer do not require passivation.
However, if the upper structure is galvanized steel,
passivation is required on the galvanized area including
any Hot Dip Galvanized After Fabrication (HDGAF) coil(s).
Biological Control
• The warm, oxygen and nutrient rich environment
inside evaporative cooling equipment provides an ideal
environment conducive to the growth of algae, slime, and
other micro-organisms. Uncontrolled, this can reduce heat