Hanna Instruments HI 96725 - Manual (Page 4)

6 7
PRINCIPLE OF OPERATION
Absorption of Light is a typical phenomenon of interaction between electromagnetic radiation and
matter. When a light beam crosses a substance, some of the radiation may be absorbed by
atoms, molecules or crystal lattices.
If pure absorption occurs, the fraction of light absorbed depends both on the optical path length
through the matter and on the
physical -chemical characteristics of the substance according to the
Lambert-Beer Law:
-log I / I
o
=
ε
λ
c d
or
A =
ε
λ
c d
Where:
-log I / I
o
= Absorbance (A)
I
o
= intensity of incident light beam
I = intensity of light beam after absorption
ε
λ
= molar extinction coefficient at wavelength λ
c = molar concentration of the substance
d = optical path through the substance
SPECIFICATIONS
Range Free Cl
2
0.00 to 5.00 mg/L
Total Cl
2
0.00 to 5.00 mg/L
Cyanuric Acid 0 to 80 mg/L
pH 6.5 to 8.5
Resolution 0.01 mg/L from 0.00 to 3.50 mg/L Cl
2
0.10 mg/L above 3.50 mg/L Cl
2
1 mg/L Cyanuric Acid
0.1 pH
Accuracy Free Cl
2
±0.03 mg/L ±3% of reading @ 25°C
Total Cl
2
±0.03 mg/L ±3% of reading @ 25°C
Cyanuric Acid ±1 mg/L ±15% of reading @ 25°C
pH ±0.1 pH @ 25°C
Typical EMC Deviation ±0.01 mg/L Cl
2
±1 mg/L Cyanuric Acid
±0.1 pH @ 7.0 pH
Light Source Tungsten lamp
Light Detector Silicon Photocell with narrow band interference filter @ 525nm.
Method For Cl
2
: Adaptation of the USEPA method and Standard Method 4500-
Cl G. The reaction with reagents causes a pink tint in the sample.
For Cyanuric Acid: Adaptation of the turbidimetric method. The reac-
tion between cyanuric acid and the reagent causes a white suspension
in the sample.
For pH: Phenol red method. The reaction with reagents causes a red
tint in the sample.
Environment 0 to 50°C (32 to 122°F)
max 95% RH non-condensing
Battery Type 1 x 9 volt
Auto-Shut off After 10' of non-use in measurement mode;
after 1 hour of non-use in calibration mode;
with last reading reminder.
Dimensions 192 x 104 x 69 mm (7.6 x 4.1 x 2.7")
Weight 360 g (12.7 oz.).
REQUIRED REAGENTS
Code Unit
Description Quantity/test
HI 93701-0 Free Cl
2
DPD Powder Reagent 1 packet
HI 93711-0 Total Cl
2
DPD Powder Reagent 1 packet
HI 93722-0 Cyanuric Acid 1 packet
HI 93710-0 pH 5 drops
PRECISION AND ACCURACY
Precision is how closely repeated measurements
agree with each other. Precision is usually
expressed as standard deviation (SD).
Accuracy
is defined as the nearness of a test
result to the true value.
Although good precision suggests good accuracy,
precise results can be inaccurate. The figure
explains these definitions. In a laboratory using
a standard solution of 1.00 mg/L chlorine and a
representative lot of reagent, an operator obtained
with a single instrument a standard deviation of
0.02 mg/L.