General operating procedure – LaMotte DCL-20 Colorimeter User Manual
Page 7
GENERAL OPERATING PROCEDURE
1. Rinse a clean colorimeter tube (0967) with sample water. Fill to the 10 mL line with sample.
2. Select the appropriate wavelength (1 to 7) from the “Select Wavelength” knob. Insert tube into the colorimeter
chamber. (Press firmly on the tube, overcoming the slight resistance, to make sure the tube rests on the bottom of the
chamber.)
3. Press the “30 Second Read” button (the BAT and ~ symbols will flash on briefly). Adjust instrument with “Set Blank”
control until meter reads exactly 100%T. The instrument is now ready to read an unknown sample.
NOTE: See Battery Replacement section for more information.
4. Perform test outlined in the recommended procedures.
5. Insert sample into the colorimeter and press the “30 Second Read” button. As soon as the reading stabilizes
(usually 5–7 seconds), record the reading.
6. Consult the calibration chart for the corresponding concentration. For example, a reading of 75%T would be found by
reading 70%T on the left column of the chart and 5 across the top of the chart. Read down the column until the
columns intersect. The value at the intersection represents concentration in parts per million (ppm) or milligrams per
liter (mg/L).
TYPICAL CALIBRATION CHART
%T
9
8
7
6
5
4
3
2
1
0
90
80
70
0.00
0.01
0.01
0.02
0.02
0.02
0.03
0.03
60
0.04
0.04
0.04
0.05
0.05
0.06
0.06
0.06
0.07
0.07
50
0.08
0.08
0.08
0.09
0.09
0.10
0.10
0.10
0.11
0.11
40
0.11
0.12
0.12
0.13
0.13
0.13
0.14
0.14
0.14
0.15
30
0.15
0.16
0.16
0.16
0.17
0.17
0.18
0.18
0.19
0.19
20
0.20
0.20
0.21
0.22
0.22
0.23
0.24
0.25
0.26
0.27
10
0.28
0.30
NOTE:
The num ber of dec i mal places in each num ber in the cal i bra tion chart is pro vided for in ter po la tion pur poses
only and does not nec es sar ily re flect the sen si tiv ity of each test.
NOTE:
%T read ings above the high est %T value on the chart should be in ter preted as 0 ppm. For ex am ple, on the
above chart, read ings above 77%T would cor re spond to 0 ppm. Some tests may have re sults above 100%T.
7
BAT
1985-01 • 10/01