Grundfos DIT, Инструкция по установке и эксплуатации

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13
9.3.3 Blank test
For some parameters an additional blank test is necessary, as the
reagents have a certain inherent colour, which occurs even if
there is no co-reactant at all. The zero value described above is
based upon the characteristics of the system "photometer, vial
and sample" and therefore is the same for all parameters.
For doing the blank test, the measurement has to be executed
with the diluting water instead of the sample in order only to
determine the colouring caused not by the reaction. All analysis
steps, such as reagent-adding and waiting times, are the same.
It is also possible to choose either detailed operator guidance or
expert mode.
After the blank test, no result will be shown. It is, however, stored
by the instrument and will later be subtracted from the measuring
result.
See section
13. Error messages and error correction
.
9.3.4 Dilution
If the measuring result exceeds the measuring range (the error
message "value exceed" is displayed), the sample water can be
diluted with distilled water. See section
6.5 Measuring ranges and
tolerances
.
In this case, proceed as follows:
• At the step "fill in 10 ml sample" requested on the display, first
add 9 ml distilled water with the syringe.
• Then add 1 ml sample water with the syringe, close the vial
and shake.
• Continue with the measurement as requested on the display.
• Multiply the measuring result by 10: result in mg/l or ppm.
9.4 Aluminium
Reagent not for sea-water use!
Before determining the aluminium concentration, a blank
test has to be made. See section
9.3.3 Blank test .
9.4.1 Aluminium determination
1. Select "photom." in the main menu, and press [OK].
2. Select "aluminium", and press [OK].
3. Select "measure" or "blanktest", and press [OK].
4. Fill a standard vial with 10 ml of the water sample. In case of
blank test: 10 ml of the diluting water. Press [OK].
5. Add one level spoon (grey) of Al reagent 1, close the vial and
shake. Press [OK].
6. Add three drops of Al reagent 2, close the vial and shake.
Press [OK].
7. Add four drops of Al reagent 3, close the vial and shake.
Press [OK].
8. Wait for seven minutes.
9. Insert the vial, start the measurement with [OK], and read the
result.
–
Result: aluminium concentration in mg/l or ppm
.
10.Press [OK].
– Printer or memory being selected: Print or save result.
Measurement is finished.
– Printer or memory not being selected: Measurement is
finished.
Caution
The blank test is necessary after commissioning,
after battery exchange or recharging of a totally
discharged accumulator and before the use of
new reagent batches.
Caution
Carry out the dilution process very carefully in
order to guarantee the utmost accuracy.
Determination
method
Reaction of Al
3+
with Chromazurol-S in
weakly acetate-buffered medium with
production of a red-violet colorant
Measuring range 0.02 to 0.5 mg/l Al
3+
Reagent
temperature range
Higher than 25 °C
Analysis time About seven minutes
Number of
analyses per
reagent set
About 200
Warning
Reagent 2 contains dimethylsulfoxide.
R 36/38: Irritating to eyes and skin.
S 26: In case of contact with eyes, rinse
immediately with plenty of water and seek
medical advice.
Note
At storage under 20 °C the elements of reagent 2
crystallise. If that is the case, warm up the
reagent slightly and shake.