TM 5-6630-215-12
g. If a second filling of the micro burette is necessary, as men-
tioned above, make certain that the final result includes the value of
the original divisions as well as the additional quantity added.
For example, a color endpoint is reached at the 13.4 (two subdivisions
below the 13 line) mark on the second filling of the micro burette.
The result is 13.4 plus 20 or a total of 33.4 divisions. This number
of divisions is then multiplied by the specific constant factor listed
in each titrimetric procedure to yield the concentration of the
parameter being tested.
h.
As soon as the specific color change is observed (endpoint),
stop any further movement of the micro burette plunger.
i. Read the result of the test at that point on the scale that is
directly opposite the bottom of the plunger tip.
j. If additional tests, using the same reagents, are to be per-
formed, the burette is refilled to the zero graduation.
If no addi-
tional tests are to be made, the titration solution in the burette is
discarded and the burette and titration vial are thoroughly rinsed
with demineralized water and returned to the kit.
2-12.
WASH BOTTLE WITH RESIN.
The wash bottle contains mixed bed
demineralize resin which will provide water of a purity beyond that
of ordinary distilled water.
a.
Refill the wash bottle with resin with the cleanest water
available.
If the water is turbid filter with turbidity - free water
filter equipment (para 2-21).
b.
The wash bottle with resin may be used until the resin changes
from blue to yellow.
On rare occasions, a raw water may carry an
anaerobic bacteria which will grow in the resin and liberate a rotten
odor.
If this happens, the wash bottle with resin must be replaced.
2-13.
CONVERSION FACTORS.
a.
Hardness-Alkalinity Calcium Carbonate (CaCo3) (table 2-4).
b.
Oxygen, Dissolved.
Table 2-5 lists the mg/l dissolved oxygen
in water at saturation for various temperatures and atmospheric
pressures.
The table was formulated in a laboratory using pure water;
thus the values given should be considered as only approximations when
estimating the desired oxygen content of a particular body of surface
water.
2-12
