IDC INDUCED DRAFT EVAPORATIVE CONDENSERS
MAINTENANCE
S140-500 IOM (FEB 08)
Page 25
be increased to eliminate as much excess particulate as
possible.
Possible Cause # 2: Water pH is Out Of Range
•
pH must be less than 9.0 and greater than 6.5. Water
treatment equipment is designed to slug feed biocides of
various pH levels to minimize bacterial counts. Skimping on
chemical will allow algae blooms and high bacterial counts.
Excessive or chlorine based biocides may lower pH and
shorten the life of Zinc-protected steel components.
•
Calibrate biocide chemical injection rate. Drain system and
make-up with clean water to rebalance pH. Run system
for 24 hours and observe any change in pH range.
•
Repeat above steps and determine if process is add-
ing bases/acids or is in some way affecting overall pH
levels in the cooling water flow. Eliminate any leaks
(process-to-cooling-water) that may be changing pH levels
in the water fl ow.
5.3 Condition: Excessive Slime Plugging Water
Air Passages
Possible Cause # 1: Low Blow-down Rate
•
Calibrate IDC cooling water blow-down controls. Readjust
if necessary to meet requirements specifi ed by cooling
system design engineer.
Possible Cause # 2: High Bacterial Count
•
Take sample for lab analysis. If analysis indicates high
bacterial count, start by physically removing excess slime.
Calibrate chemical biocide feed. Drain water from system
and make-up with fresh supply before returning system
to service.
Possible Cause # 3: High Nutrient Levels
•
Take sample for analysis. If analysis indicates excessive
nutrients, repeat above steps.
•
Take samples during operation to determine if source
of nutrients is airborne or leaked from process by heat
exchanger, etc. Eliminate source or increase blow-down
rates accordingly if discharge permit allows.
5.4 Condition: Low or High Water Level
Possible Cause # 1: Drain/Overfl ow Piping Clogged
•
Remove debris and refi ll basin to test fl ow.
Possible Cause # 2: Makeup Valve Malfunctioning
•
Replace makeup valve assembly and refi ll basin to operat-
ing level.
Possible Cause # 3: Pump Output Incorrect
•
Take fl ows and pressure readings from pump/piping in
question. Determine if pump may be throttled with means
of butterfl y valve. Make necessary throttle adjustments
and check basin after (1) hour of operation.
Possible Cause # 4: Equipment/Piping Leak
•
Make-up water pressure too high (maximum should be no
more than 60 PSI). If necessary, install regulator in city
water makeup piping.
•
Inspect all equipment and piping for water leak. If found,
shut off system. Fix leak or bypass if possible before re-
turning system to operation.
5.5 Condition: Excessive Noise or Vibration
Possible Cause # 1: Debris-laden Fan Blades
•
Clean/remove debris from fan and retest unit operation.
Possible Cause # 2: Improperly Aligned Drive
Components
•
Inspect fan and drive assembly for improperly aligned drive
components. Replace failed components and realign drive
assembly per maintenance instructions.
Possible Cause # 3: Damaged Noise Control Device
•
Check device for damage to insulation, door, wall panels,
or damaged inlet louvers.
Possible Cause # 4: Loose Tower Components
•
Inspect for loose components/fasteners and repair or
replace as necessary.
Possible Cause # 5: Out Of Specifi cation Fan Speed
•
Determine actual drive ratio by turning fan slowly by hand
and comparing the number of motor sheave revolutions
for one revolution of the fan. Multiply actual ratio by the
speed (RPM) noted on the IDC unit’s motor nameplate.
•
Contact factory for order information regarding original fan
speed. If different than actual, replace existing, improper
replacement sheaves or belt.
Possible Cause # 6: Out Of Specifi cation IDC Unit
Structural Steel or Supports
•
Failed structural steel/support beams, isolators, or attach-
ing hardware. Replace any component having excess
corrosion or fatigued connections.
Possible Cause # 7: Excessive Background Noise/
Refraction
•
Turn off IDC and have accurate sound readings taken
during “noisy” hours of operation. Turn on IDC and take
simultaneous readings with unit in operation. If background
noise exceeds IDC sound levels, consider sound isolation
of background noise sources.