UFC 3-240-13FN
25 May 2005
The COC is:
Bmhos
C = 7uy8
Mmhos
C = 800 300 = 2.67
NOTE: The parameters of conductivity or chloride concentration are used commonly
for such measurements. Other water quality parameters can be used, but sometimes
with inaccurate results (i.e., calcium, magnesium, alkalinity, and silica can form
deposits, meaning they drop out of solution). COC based on these parameters could be
considerably less than that based on conductivity or chlorides. Similarly, chemical
additions of sulfuric acid can yield higher sulfate levels than those species cycled up
naturally.
4-2.1.2.3
Controlling COC. A simple, sometimes overlooked rule: To increase
COC, decrease blowdown; to decrease COC, increase blowdown.
4-2.1.2.4
Relationship Between COC and Makeup. COC and makeup
requirements are related to the temperature drop across a cooling tower and to the
recirculating rate of the tower. As shown in Figure 4-15, for a recirculating tower with
water temperature drops of 5.5 C (10 F), 11 C (20 F), and 16.5 C (30 F), the
makeup water requirement decreases rapidly as COC is increased to about 4 or 5, with
lower incremental reductions at higher COC; therefore, COC can be adjusted
(increased) to allow for reductions in water use (water conservation) and for reductions
in the amount of water treatment chemicals used.
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