Hach-Lange PHOSPHAX sigma Basic User Manual - Manual (Page 95)

English 95
• 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).
Dosing pumps
The four hose dosing pumps used are responsible for the transport of all
fluids.
They are stepper motor-controlled and variable in speed and direction of
rotation. The dosing hoses are routed with the help of pump cassettes
via the pump rollers. For the feeding of the reagents C and D, a two-
channel pump (two pump cassettes) is used, for the other pumps a one-
channel pump (one pump cassette) is used.
Wear on the pump rollers is indicated by strong groove formation, which
can lead to defective dosing. In this case, the exchange of the pump
rollers is recommended as a precaution.
Figure 9 Dosing pump head during roller exchange
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!
N O T I C E
For a long-term shutdown (over 48 hours) the
pump cassettes must be released in order to relieve the dosing hoses — but
because of the return flow risk the hoses should first be removed from the
screw caps (canister lids)! Please observe during the handling of the reagents the
safety notes under
section Exchange of the reagents .
Pump cassette
Pump roller