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NOTES
28
CL
DPD-3 Total Chlorine Test Procedure
This procedure is only valid when run as a continuation of the
®
eXact
Strip Micro CL (DPD-1 Free Chlorine ) Test Procedure
located on the previous page.
REMOVE STRIP
7
Remove one (1) eXact
®
Strip Micro CL (DPD-3), Part No. 486638 from the bottle before
beginning the test. Set the strip in a dry, convenient place and recap the bottle immediately.
DIP STRIP AND PRESS "READ"
8
Dip the eXact
®
Strip Micro CL (DPD-3) into the CELL and immediately press READ. This
starts the 20 SECOND countdown timer. During this time move the strip in a gentle back
and forth motion. Remove and discard the strip when the time displays 1. The cursor will
move across the display, informing you that it is about to measure the sample. This result is
automatically stored in CL1.
PRESS READ AGAIN
9
Press READ again and the meter will count down and display the next reading. If this
reading matches the previous result, then record this as the Total Chlorine result. This value
is automatically stored in CL1. If reading has increased by 0.01, press READ again and
repeat as before. After testing is completed, rinse cell immediately. Record the Total Chlorine
as the highest value the meter displayed.
*NOTE: Standard Method (4500-Cl G, procedure for total chlorine) requires the reading to
be made after 2 minutes from the time the KI is added. For compliance testing, you must
time the two minutes and then make your measurement. NOTE: From testing in our lab,
water samples above 70°F (20°C), generally, reach a stabilized reading quickly.
eXact
Strip Micro CL (DPD-1/DPD-3/DPD-4) Interferences (part nos. 486637/486638/486670)
®
Interfering Substance
Interfering Levels & Treatments
Acidity
If sample has acidity above 150mg/L CaCO
full color. Neutralize to pH 6.0 to 7.0 with 0.5N Sodium hydroxide.
Alkalinity
If sample has alkalinity above 200mg/L CaCO
full color. Neutralize to pH 6.0 to 7.0 with 0.5N Sulfuric acid.
Bromine & Bromamines, Br
Color similar to free chlorine reaction at all levels.
2
Chlorine Dioxide, ClO
Color similar to free chlorine reaction at all levels.
2
Copper, Cu
+2
Color development is reduced above 10 ppm (mg/L).
Iodine, I
Color similar to free chlorine reaction at all levels.
2
Manganese, oxidized (Mn
+4
, Mn
+7
)
See AWWA procedure 4500-CL F, 1(d) for removal of interferences.
or Chromium, oxidized (Cr
+6
)
Monochloramines (NH
Cl)
Monochloramine interferences are known to occur in free chlorine
2
(applies to DPD-1 only)
DPD methods. This interference is dependent on temperature and
monochloramine concentration.
Ozone, O
Color similar to free chlorine reaction at all levels.
3
Peroxides
Interference is possible.
pH
Typical pH samples of potable water with a pH of 6.0 to 9.0 are
OK. If outside this range adjust to pH 6.0 to 7.0 using acid
(0.5N Sulfuric acid) or base (0.5N Sodium hydroxide).
test may not develop
3
test may not develop
3
5
CL1
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