Hanna Instruments HI 95717 - Manual (Page 7)

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
or
INTERFERENCES
• Calcium (Ca
2+ ):
• Chloride (Cl - ):
• Ferrous iron (Fe 2+ ):
• Magnesium (Mg 2+ ):
• Sulfide (S 2- )
above 10,000 mg/L as CaCO
3
.
above 150,000 mg/L as Cl - .
above 100 mg/L as Fe 2+ .
above 40,000 mg/L as CaCO
3
.
• Add the content of one packet of HI
93717B-0 Phosphate HR Reagent B to
the cuvet. Replace the cap and shake
gently until dissolution is complete.
• Replace the cuvet into the holder and
ensure that the notch on the cap is
positioned securely into the groove.
• Hold READ/TIMER for three seconds. The
display will show the countdown prior to
measurement.
Alternatively, wait for 5 minutes and
just press READ/TIMER.
In both cases “SIP” will blink during
measurement.
• The instrument directly displays
concentration in mg/L of phosphate on
the Liquid Crystal Display