(g) Expel, with force,
the dropper full of orthotolidine
(yellow cap) into the cell in the left opening of the comparator.
Immediately expel, with force, the dropper of arsenite (red cap) into
the same cell.
The immediate addition of the arsenite is important to
make a correct residual reading.
This solution in the left opening is
(h) Hold the comparator to your eye, and face a good light
source (daylight but not the direct rays of the sun, daylight illumina-
tor, or artificial light reflected from a white surface).
your fingers do not cover the light window in the back of the compara-
Rotate the chlorine color comparator disc until a color on the
disc matches the color of the indicator cell (left hand).
can be made directly from the round window in front of the comparator.
The value is expressed in milligrams per liter (mg/l).
(i) If the color of the indicator (left hand) cell is between
two colors on the chlorine color comparator disc, the value must be
estimated between the readings.
(j) When test has been completed, remove both sample cells
from the comparator, empty the samples and wash the cells with clean
In the event that your WQAS-ENGR is received
equipped with Color Comparator NSN6630-01-044-0334
2-16.1) the test for free chlorine residual
is as para.
22 e (2).
(2) Color Comparator, Hydrogen Ion and Residual Chlorine
(a) Determination of free Chlorine Residual - In
determining these values, the Comparator measures them in simple
numbers in the reading window.
A prism eyepiece is furnished and
must be positioned on the bosses in order to insure accuracy.
DPD (Diethyl-P-Phenylene Diamine) poison -- may
be fatal -- induce vomiting.
Wide range DpH Indicator Solution -- poison --
may be fatal or cause blindness if swallowed.
Cannot be made nonpoisonous.
Flammable -- keep
away from sparks.
If swallowed -- call a physi-
Induce vomiting by giving a
tablespoon of salt in a glass of warm water.
two (2) tablespoons of soda in a glass of warm
Have patient lie down and cover the eyes
to exclude light.