Hach CL17 User Manual

Page 58
General Information
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General Information
Figure 22 CL17 Chlorine Analyzer
Method of Analysis
Free available chlorine (hypochlorous acid and hypochlorite ions) oxidizes the
DPD indicator reagent at a pH between 6.3 and 6.6 to form a magenta-
colored compound. The depth or intensity of the resulting color is proportional
to the concentration of chlorine in the sample. A buffer solution specifically for
free chlorine maintains the proper pH.
Total available chlorine (free available chlorine plus combined chloramines)
is determined by adding potassium iodide to the reaction. Chloramines in
the sample oxidize iodide to iodine, which, along with any free available
chlorine, oxidizes DPD indicator to form the magenta color at a pH of 5.1.
A different buffer solution containing potassium iodide maintains reaction pH.
After the chemical reaction is complete, the optical absorbance at 510 nm is
compared to the absorbance measured through the sample before the
reagents were added. Chlorine concentration is calculated from the difference
in absorbance.
EX
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Chlorine
m
g/L
M
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Hach CL17 Specifications

General

Power Requirements	100-240 V AC, 50/60 Hz
Outlet Pressure	Atmospheric
Measurement Method	Colorimetric DPD method
Sample Interval	2.5 minutes
Operating Temperature	5 - 40 °C (41 - 104 °F)
Parameter	Free or Total Chlorine
Operating Humidity	5 - 95% non-condensing
Sample Temperature	0 to 40°C (32 to 104°F)
Sample Flow Rate	200 to 500 mL/min
Power Consumption	Approximately 50 W
Output	4-20 mA, RS-232
Relays	Two relays
Enclosure	NEMA 4X
Resolution	0.01 mg/L
Accuracy	±5% or ±0.03 mg/L (whichever is greater)