October 2012
6-13
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Make sure the tower fill valve cuts off cleanly when the tower basin is full to mini-
mize wasted water from leaks.
Choosing aWater Treatment Vendor
When considering a water treatment vendor, select one that focuses on water ef-
ficiency. Request an estimate of the quantities and costs of treatment chemicals, vol-
umes of make-up and blowdown water expected per year, and the expected cycles
of concentration that the vendor plans to achieve. Select a vendor that can achieve
high cycles of concentration while keeping costs for chemicals low.
Maximizing Cycles of Concentration
In addition, to maximize cycles of concentration, consider the following:
••
Calculate and understand the cooling tower’s cycles of concentration. Check the
ratio of make-up water to blowdown water. Then check the ratio of conductiv-
ity of blowdown water and make-up water. Use a handheld conductivity meter
if the tower is not equipped with permanent conductivity meters. These ratios
should match the target cycles of concentration. If both ratios are not roughly
the same, check the tower for leaks. If the tower is not maintaining target cycles
of concentration, check the conductivity controller, the make-up water valve, and
the blowdown valve for proper operation.
••
Work with the cooling tower water treatment vendor to maximize the cycles
of concentration. Many systems operate at two to four cycles of concentration,
while six cycles or more might be possible. Increasing cycles from three to six re-
duces cooling tower make-up water by 20 percent and cooling tower blowdown
by 50 percent.
••
Work with the water treatment vendor to add chemicals to the system to control
scaling and chemical buildup. Critical water chemistry parameters that require re-
view and control include pH, alkalinity, conductivity, hardness, microbial growth,
biocide, and corrosion inhibitor levels.
••
When increasing cycles of concentration, ensure that discharged water meets
allowable water quality standards.
ReadingWater Chemistry Reports
The water treatment vendor should produce a report every time he or she evaluates
the water chemistry in the cooling tower. When these reports are received, read them
to ensure that monitoring characteristics, such as conductivity and cycles of concen-
tration, are within the target range. By paying proper attention to the water chemis-
try reports, problems within the system can be identified quickly.
6.3
Cooling Towers
