WARNING
TM 5-6630-215-12
i.
Turbidity Test Kit (fig. 2-20).
(1) Turbidity interferes with color analysis. This test is made
by comparing the turbidity of measured amount of the sample being
analyzed with an identical amount of turbidity-free water to which an
accurately measured amount of standardized turbidity reagent has been
added.
The readings are made by looking down through the column of
liquid.
If turbidity is present, it will interfere with the passage
of light through the column of liquid.
Small amounts of turbidity will
cause a “blurring”
of the black dot in the bottom of the tube.
Large
amounts of turbidity may provide sufficient “cloudiness” so that it is
not possible to see the black dot when looking down through the column.
Any color that may be present in the sample should be disregarded.
This determination is concerned only with the haziness or cloudy
nature of the sample.
Do not allow reagents to come in contact with
skin or eyes.
Do not ingest.
Most chemical
reagents are corrosive or poisonous.
NOTE
Store reagent in a cool, dark place away from
direct sunlight.
Shake reagent vigorously before
using.
(2) Turbidity Test Procedure.
(a) Fill one turbidity tube to the 50 ml graduation (top line)
with the water to be tested.
If the black dot in the bottom of the
tube is not visible when looking down through the column of liquid,
pour out a sufficient amount of the test sample so the tube is filled
to the 25 ml graduation (top line).
Most determinations are made with
a 50 ml sample.
(b) Fill the second turbidity tube with an amount of turb-
idity-free water that is equal to the amount of sample being measured
(25 or 50 ml).
See instructions for turbidity-free water which
follows in para 2-22j.
(c) Place the two tubes side-by-side and note the differnece
of clarity.
(d) Add 0.5 ml of the standard turbidity reagent to the “clear
water” turbidity tube.
Seal with thumb or other stopper, invert both
tubes to get equal distribution of the turbid particles.
Inspect as in
step (a).
If the turbidity in the sample being tested is greater than
the turbidity in the treated mixture in the second turbidity tube,
continue to add the standard turbidity reagent in increments of 0.5 ml
2-80
