22
the minimum amount of blowdown (percent of flow) required to maintain different
concentrations with various cooling ranges*:
* Range = Difference between hot water temperature coming to tower and cold water tem-
perature leaving tower.
EXAMPLE:
700 GPM circulating rate, 18°F cooling range. To maintain 4
concentrations, the required blowdown is 0.458% or .00458 times 700 GPM,
which is 3.2 GPM.
If tower is operated at 4 concentrations, circulating water will contain four
times as much dissolved solid as the makeup water, assuming none of the
solids form scale or are otherwise removed from the system.
When water treatment chemicals are added, they should not be in-
troduced into the circulating water system via the cold water basin
of the cooling tower. Water velocities are lowest at that point, which
results in inadequate mixing.
Belt Tensioning
The belt tension is adjusted by loosening the 8 bolts that secure the motor
mount frame to the belt drive frame, then loosen the retaining nuts on the two
threaded rods and turn the threaded rods to apply proper tension. Apply the
same quantity of turns to each threaded rod to insure that the tensioning frame
remains parallel to the mechanical support beams. Retighten hardware. Ideal
tension is the lowest tension at which the belt will not slip under peak load
conditions. Check tension frequently during the first 24-48 hours of run-in
operation. Overtensioning shortens belt and bearing life. Keep belts free from
foreign material which may cause slipping. Never apply belt dressing as this will
damage the belt and cause early failure. A Dodge
®
V-Belt Tension Tester is an
alternate method for tensioning V-belts. Check with you local belt supplier.
maintenance
Note
Cooling Range
Number of Concentrations
1.5X
2.0X
2.5X
3.0X
4.0X
5.0X
6.0X
5º F
.78
.38
.25
.18
.11
.08
.06
10º F
1.58
.78
.51
.38
.25
.18
.14
15º F
2.38
1.18
.78
.58
.38
.28
.22
20º F
3.18
1.58
1.05
.78
.51
.38
.30
25º F
3.98
1.98
1.32
.98
.64
.48
.38
Multipliers are based on drift of 0.02% of the circulating water rate.