Hanna Instruments hi 95729 Manual Do Utilizador

7

A microprocessor controlled special tungsten lamp emits radiation which is first optically
conditioned and beamed to the sample contained in the cuvet. The optical path is fixed by the
diameter of the cuvet. Then the light is spectrally filtered to a narrow spectral bandwidth, to
obtain a light beam of intensity 

I

o

 or 

I

.

The photoelectric cell collects the radiation 

I

 that is not absorbed by the sample and converts

it into an electric current, producing a potential in the mV range.
The microprocessor uses this potential to convert the incoming value into the desired measuring
unit and to display it on the LCD.
The measurement process is carried out in two phases: first the meter is zeroed and then the
actual measurement is performed.
The cuvet has a very important role because it is an optical element and thus requires particular
attention. It is important that both the measurement and the calibration (zeroing) cuvets are
optically identical to provide the same measurement conditions. Whenever possible use the same
cuvet for both. It is necessary that the surface of the cuvet is clean and not scratched. This to
avoid measurement interference due to unwanted reflection and absorption of light. It is
recommended not to touch the cuvet walls with hands.
Furthermore, in order to maintain the same conditions during the zeroing and the measuring
phases, it is necessary to close the cuvet to prevent any contamination.

1) Liquid Crystal Display (LCD)
2) Cuvet Holder
3) Cuvet alignment indicator
4) ON/OFF key

5) ZERO key
6) READ/TIMER key

7) CAL CHECK

 

key

FUNCTIONAL DESCRIPTION

14

INTERFERENCES

Chlorine interferes at all levels: to eliminate Cl

2

 interference add to the 10 mL unreacted

sample, 1 drops of the optional HI 93703-53 Chlorine Remover, for each 2 mg/L of chlorine.
Negative interferences may be caused by:
Alkalinity (as CaCO

3

) above 5000 mg/L

Aluminum above 0.1 mg/L

Iron, ferric above 10 mg/L
Positive interferences may be caused by:
Chloride above 7000 mg/L

Phosphate, ortho above 16 mg/L

Sodium hexametaphosphate above 1.0 mg/L

Sulfate above 200 mg/L

• Replace the cap to the cuvet, and shake gently

a couple of times.

• Place the cuvet with the reacted sample into

the holder and ensure that the notch on the cap
is positioned securely into the groove.

• Hold READ/TIMER 

for three seconds

 and the

display will show the countdown  or,
alternatively, wait for two minutes.

• Press READ/TIMER and “SIP” will blink during

measurement.

• The instrument directly displays concentration

in mg/L (ppm) of fluoride on the Liquid Crystal
Display.

Note

:

For wastewater or seawater samples, before
performing measurements, distillation is
required.

r

e

a

c

t

e

d

s

a

m

p

l

e