LaMotte LTC3000wi Turbidity & Chlorine Lab Meter - Manual (Page 71)

for these reagents go to www.lamotte.com. To obtain a printed copy,
contact LaMotte by e-mail, phone or fax.
NOTE: For the most accurate results, samples over 6 ppm chlorine
should be diluted with chlorine demand free water and re-tested.
NOTE: The meter will remember the last scanned blank reading. It is not
necessary to scan a blank each time the test is performed. To use the
previous blank reading, instead of scanning a new one, scroll to Scan
Sample and proceed. For the most accurate results, the meter should
be blanked before each test and the same tube should be used for the
blank and the reacted sample.
DILUTION PROCEDURE
Samples and standards should be diluted with chlorine demand free
water.
TESTING TIPS
1. Wash tubes thoroughly after testing to prevent staining of tubes and
contamination of future test reactions with DPD residue.
2. When using liquid DPD reagents, invert bottle in a completely
vertical position to dispense uniform drops. Do not tilt bottle at an
angle.
3. Follow instructions. Obey time limits.
4. In samples with extremely high chlorine concentrations, above 10
ppm, the reagent system will show an initial fl ash of dark pink color
that will fade quickly. Dilute the sample and test again.
5. When testing salt water, double the amount of reagent used. Use ten
drops of each DPD liquid reagent or two DPD tablets.
6. Oxidized manganese (permanganate) will interfere with this test.
Iodine and bromine will give a positive interference.
7. A permanganate check standard is not recommended for calibration
when using the liquid DPD reagent system.
8. The averaging option is not available for the chlorine test.
9. When testing at low concentrations use the same tube for the blank
and the sample.
10. Always insert tube into the meter chamber with the same amount of
pressure and to the same depth.
11. Occasionally clean the chamber with a damp lint-free wipe, followed
by an alcohol dampened wipe. A clean chamber and tubes are
essential for reliable results.
71
Chlorine Analysis