(c) Add one crushed orthotalidine tablet (crush it with the top of the test
tablet bottle), cover the end of the tube, and shake it until the orthotolidine is completely
(d) Compare the shade of the water with the shade of the yellow band
on the tube. If the color of the water is the same shade or darker than that of the band,
the chlorine residual is equal to or greater than the number printed on the tube. If the
water has a lighter color or no color, the chlorine residual is insufficient and more
chlorine must be added.
c. Care of the Chlorination Kit. The orthotolidine tablets in the chlorination kit
will deteriorate when exposed to sunlight and/or moisture. Therefore, when the kit is not
in use, the vials of orthotolidine tablets should be tightly closed and stored in a dark
place. The bands on the comparator tubes wiII aIso fade when exposed to sunlight, so
they should be protected accordingly. It is not recommended that testing be conducted
in the direct rays of the sun.
2-9. NEW CHLORINATION KIT
improves the determination of chlorine residual and uses the N, N-diethyl-p-Phenyl-
enediamine (DPD) method.
Figure 2-3. New chlorination kit.
b. Components. The new kit contains: (1) 100 calcium hypochlorite ampules,