Application: Man Hours 2
This is applicable to both condenser water and chilled water systems. Included
are open recirculating systems, closed systems, air washers, and sprayed coil
unit and evaporative condensers. Once through systems are not applicable.
Note: This maintenance guide does not eliminate daily testing where it is an
established policy.
Special Instructions:
1. Chemicals must comply with the Environmental Protection Agency (EPA)
regulations and handled in accordance with occupational safety requirements.
Employ personal protection against corrosive or hazardous treatment chemicals
as appropriate.
2. Be familiar with the Material Safety Data Sheets of any chemicals used in the
water treatment program.
3. Water treatment specialists must be properly trained.
4. Water treatment must be based on proven standard engineering practices.
Treatment methods that claim mysterious magnetic or catalytic forces shall
not be used.
5. Follow treatment as directed by manufacturer or water treatment company.
6. Maintenance includes chemicals, chemical feeding, maintaining proper water
conditions, controlling bleed off, protecting idle equipment, and
record keeping.
7. Select water treatment methods which protect the life of equipment, maximize
heat transfer, and minimize scale, corrosion, solid matter buildup, algae,
fungi, biological growth, and water usage. Alternate biocides. Changes to
higher dosage levels may be required to control growth.
8. Ensure chemicals are properly stored, test equipment clean, and that
chemicals have not passed expiration date.
9. Special attention must be paid to wooden towers and solar heating systems
which can be more difficult to properly maintain.
10. Physical inspections of towers and piping systems are to be made to
determine water treatment effectiveness.
11. Maintain records and test results.
Items to Check & Initial Completion:
1.___ Inspect cooling tower and piping system to determine effectiveness of water
treatment.
2.___ Test each system for proper pH, total dissolved solids, conductivity,
biological dosage level, scale and corrosion inhibitors; test supply water
for base conditions.
3.___ Test for biological growth using either on-site or laboratory. Include
iron-related bacteria, sulfate reducing bacteria, slime forming bacteria,
fluorescing pseudomonas, and blue-green algae.
4.___ Add or adjust chemical and biological treatment dosage and water bleed off
rate as appropriate.
a.___ Follow treatment as directed by manufacturer or water treatment
company.
5.___ If makeup is excessive, determine source of leak and correct.
6.___ Monitor and test corrosion coupons as applicable.
7.___ Record test results, action taken, type of chemicals, and treatment
quantities used.
8.___ If treatment is not effective, it may require a change in the treatment
used or cleaning and preservation of the cooling tower and piping system.
Make-up Water:
1.___ It is advisable to frequently test the quality of make-up water used. Have
the water tested and a report performed to show the results. The following
is an example of such a report.
REPORT OF
WATER ANALYSIS
DATE:
SOURCE:
DATE ANALYZED:
TOTAL DISSOLVED SOLIDS ppm CALCIUM ppm
ORGANIC MATTER ppm MAGNESIUM ppm
SUSPENDED MATTER ppm SODIUM &
CHLOROFORM (Oil, etc.) ppm POTASSIUM ppm
pH BICARBONATE ppm
PHENOLPHTHALEIN ALK. ppm CARBONATE ppm
METHYL ORANGE ALK. ppm HYDROXIDE
HYDROXIDE ALK. ppm (as OH) ppm
HARDNESS ppm SULPHATE ppm
SPECIFIC CONDUCTANCE ppm NITRATE ppm
SILICA ppm CARBON DIOXIDE ppm
IRON ppm TURBIDITY ppm
OTHER ppm OTHER ppm
2.___ Adjust the application of chemicals as determined by the water analysis.
Cycles of Concentration:
The cycles of concentration is determined by the bleed-off rate. Typically, a
cooling tower is run between 4 to 6 cycles of concentration. Bleed-off may need
to be increased if other indicators determine adverse impact on the tower. The
following table may be used to adjust the bleed-off rate to get the cycles of
concentration needed for effective water treatment. Note that the bleed-off rate
must be substantially increased as the cycles of concentration approaches two
(2). Since bleed-off adversely impacts water conservation, try to be as
conservative as possible while still achieving an effective program.
BLEED RATE (GAL./MIN.) VS. TOWER TONNAGE
FOR VARIOUS CYCLES OF CONCENTRATION
TOWER
TONNAGE
CYCLES OF CONCENTRATION
2
3
4
5
6
7
8
BLEED RATE - GAL./MIN.
50
1.5
.75
.5
.37
.3
.25
.210
100
3.0
1.5
1.0
.75
.6
.5
.425
200
6.0
3.0
2.0
1.5
1.2
1.0
.850
250
7.5
3.75
2.5
1.87
1.5
1.25
1.060
300
9.0
4.5
3.0
2.25
1.8
1.5
1.270
400
12.0
6.0
4.0
3.0
2.4
2.0
1.700
500
15.0
7.5
5.0
3.75
3.0
2.5
2.120
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