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CHEMICALS AND CHEMICAL HANDLING 15.17

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FIGURE 15.6 Freezing temperatures
NaOCt Concentration (trade percent)
of hypochlorite solutions.
TABLE 15.3 Influence of Temperature and Strength on
Decay of Hypochlorite Solutions
Half-life (days)
% CI2 100 ° C 60 ° C 25 ° C 15 ° C
10.0 0.079 3.5 220 800
5.0 0.25 13 790 5000
2.5 0.63 28 1800 --
0.5 2.5 100 6000 --

Storage temperatures should not exceed about 85 ° F (30 ° C) because above that level,
the rate of decomposition increases rapidly. Although storage in a cool, darkened area
greatly limits the deterioration rate, most manufacturers recommend a maximum shelf life
of 60 to 90 days.
All hypochlorite solutions are corrosive to some degree and can affect the skin, eyes,
and other body tissues. Accordingly, rubber gloves, aprons, goggles, and similar suitable
protective apparel should be provided for preparing and handling hypochlorite solutions.
Areas of skin contact should be promptly flushed with large quantities of water. Every
precaution should be observed to protect containers against physical damage, to prevent
container breakage, and to minimize accidental splashing.

CHEMICAL FEED AND METERING SYSTEMS

The types of chemical feed equipment for the water treatment plant must be part of the
decision of whether gaseous, dry, or liquid chemicals are to be used.