8
installation
This is the recommended operating water level. Adjust the float valve so
that it is essentially closed at that level. Continue filling the system until
the water reaches a level approximately 4mm below the lip of the overflow.
5. If the tower equipped with flow-control valves (by others) completely open
flow-control and makeup valves. Start your pump(s) and observe system
operation. Since the water system external to the tower will have been
filled only to the level achieved in the cold water basin, a certain amount of
“pump-down” of the basin water level will occur before water completes
the circuit and begins to fall from the fill. The amount of initial pump-down
may be insufficient to cause the makeup valve to open. However, you can
check its operation and make sure reaching operating level. Then shut off
the makeup valves.
6. Some trial and error adjustment of the makeup float valve may be required
to balance the makeup water with tower operation. Ideally, the makeup float
valve setting will be where no water is wasted through the cold water basin
at pump shutdown. Overflow through the overflow is acceptable however
the water level after pump start-up must be deep enough to assure positive
pump suction.
7. If the tower is equipped with flow-control valves (by others) adjust to equalize
hot water depth in the distribution basins after reaching design water flow
rate. Each basin should have 72mm to 140mm water depth with uniform
depth from basin to basin. Fix valves in this position when depth is correct.
8. Continue pump operation for about 15 minutes after which it is recommended
the water system be drained, flushed, and refilled.
9. While operating the condensing water pump(s) and prior to operating the
cooling tower fan, execute one of the two alternative biocidal treatment
programs described in the following:
• Resume treatment with the biocide which had been used prior to shutdown.
Utilize the services of the water treatment supplier. Maintain the maximum
recommended biocide residual (for the specific biocide) for a sufficient period
of time (residual and time will vary with the biocide) to bring the system under
good biological control or
• Treat the system with sodium hypochlorite to a level of 4 to 5 mg/L free chlo-
rine residual at a pH of 7.0 to 7.6. The chlorine residual must be held at 4 to
5 mg/L for six hours, measurable with standard commercial water test kits.
If the cooling tower has been in operation and then shut down for a duration
of time and not drained, perform one of the two previous biocidal treatment
programs directly to the cooling water storage vessel (cooling tower sump,
drain down tank, etc.) without circulating stagnant water over the cooling tower
fill or operating the cooling tower fan.
After biocidal pretreatment has been successfully completed, cooling water
may be circulated over the tower fill with the fan off.
When biocidal treatment has been maintained at a satisfactory level for at
least six hours, the fan may be turned on and the system returned to service.
Resume the standard water treatment program, including biocidal treatment.
