Hach PHOSPHAX sigma Manuel D'utilisation De Base page 127

Functional description
Total phosphorus determination
In the measurement operation, the cuvette is first rinsed with the
sample, before reagent A and the homogenized sample is fed into the
cuvette. After successful mixing, the solution is briefly heated under
pressure and immediately cooled again. To determine the phosphorus
compounds now converted to orthophosphate, the reagents C and D are
fed simultaneously via the reagent dosing pump into the cuvette and
mixed. The LED photometer now determines through the intensity of the
developing blue coloration, taking into account the zero value
determined shortly before, the total phosphorus concentration.
Orthophosphate determination (depending on design)
In the measurement operation, the cuvette is first rinsed with the
sample. Then reagent A is fed into the cuvette. Through the heating, the
thermal conversion of the oxidant into sulfuric acid occurs. After the
cooling, the sample, reagent C and reagent D are fed in via the dosing
pumps. After the mixing- and reaction phase, the measurement occurs
via the LED photometer.
Calibration (approximately 15 minutes)
The process photometer PHOSPHAX Σ sigma is calibrated
automatically through a two-point measurement. The first measurement
point is determined in the course of zero point determination for each
individual measurement, the second measurement point is determined
in the course of calibration with the standard solution. The exact
concentration level for the standard solution is located on each individual
bottle
(1.95–2.05 mg/L P) and is entered in the [+SETTINGS] menu under
menu item [STANDARD].
Calibration should always then be triggered if changes have been made
to the following device components:
• Reagents
• Dosing hoses
• Dosing pumps
• Cuvette
• Electronics
The process of a calibration corresponds exactly to the process of a
normal measurement in the measurement operation. The only difference
is that instead of the current waste water sample the standard solution is
measured. The current output is not influenced by the calibration cycle.
The last measurement value before the calibration is recorded and is
only updated on completion of the calibration after a new measurement.
Automatic cleaning (approximately 15 minutes)
PHOSPHAX Σ sigma produces its cleaning solution by itself. To do this,
the digestion reagent A is fed into the cuvette. Then the thermal
conversion of the oxidant into sulfuric acid occurs. Now the entire
sample path to the end of the approximately 1.2 m long sample feed
hose outside the housing is filled with this hot acid. After 5 minutes of
reaction time, the used cleaning solution is rejected via the drain hose.
Safety panel
Within the digestion unit temperatures of over 100 °C are worked with,
under pressure and with a strongly acidic digestion agent. This requires
an increased safety effort.
For this reason, a safety panel is located in front of the entire analysis
part. On the internal side of the safety panel is the transparent safety
bolt, which is engaged in a special lock system behind the photometer
baseplate.
This lock only opens in the [+SERVICE] menu, after the device has
reached its default status (cuvette emptied, unpressurized and at
ambient temperature).
N O T I C E
For all work inside the analysis part (dosing- and connecting hoses, pumps,
valves, digestion unit), this safety panel must first be removed and must be
positioned back before the measurement operation!
Dosing pumps
The four hose dosing pumps used are responsible for the transport of all
fluids.
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