SPX Cooling Technologies CoolingTower Marley MCW - Manual (Page 19)

19
The following table shows 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
temperature 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 belts are adjusted by means of a hinged base with tensioning bolts
accessible through the access panel/fan guards. Check tension frequently
during the first 24-48 hours of run-in operation. To properly adjust the
belt tension, position the fan motor so that moderate pressure on the belt
midway between the sheaves will produce a
1 ⁄
2
"deflection. 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
Cooling Range
Number of Concentrations
1.5X 2.0X 2.5X 3.0X 4.0X 5.0X 6.0X
5°F .78 .38 .25 .18 .11 .08 .06
10°F 1.58 .78 .51 .38 .25 .18 .14
15°F 2.38 1.18 .78 .58 .38 .28 .22
20°F 3.18 1.58 1.05 .78 .51 .38 .30
25°F 3.98 1.98 1.32 .98 .64 .48 .38
Multipliers are based on drift of 0.02% of the circulating water rate.
Note