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Total Chlorine Test Procedure
7. REMOVE STRIP
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.
8. DIP STRIP AND PRESS "READ"
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.
9. PRESS READ AGAIN
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 quicker then 2 minutes.
eXact® Strip Micro CL (DPD-1/DPD-3/DPD-4) Interferences (part nos. 486637/486638/486670) 9
| Interfering Substance | Interfering Levels & Treatments |
| Acidity | If sample has acidity above 150mg/L CaCO3 test may not develop full color. Neutralize to pH 6.0 to 7.0 with 0.5N Sodium hydroxide. |
| Alkalinity | If sample has alkalinity above 200mg/L CaCO3 test may not develop full color. Neutralize to pH 6.0 to 7.0 with 0.5N Sulfuric acid. |
| Bromine & Bromamines, Br2 | Color similar to free chlorine reaction at all levels. |
| Chlorine Dioxide, ClO2 | Color similar to free chlorine reaction at all levels. |
| Copper, Cu+2 | Color development is reduced above 10 ppm (mg/L). |
| Iodine, I2 | Color similar to free chlorine reaction at all levels. |
| Manganese, oxidized (Mn+4, Mn+7) or Chromium, oxidized (Cr+6) | See AWWA procedure 4500-CL F, 1(d) for removal of interferences. |
| Monochloramines (NH2Cl) (applies to DPD-1 only) | Monochloramine interferences are known to occur in free chlorine DPD methods. This interference is dependent on temperature and monochloramine concentration. |
| Ozone, O3 | Color similar to free chlorine reaction at all levels. |
| 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). |
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