Metrohm 757 VA Computrace - Manual (Page 166)

7 How to ...?
757 VA Computrace – Software
156
7.9 Diagnostic procedures
Check the purging
1. Connect the inert gas to the 757 VA Computrace Stand (see
Hardware Manual).
2. Make sure that the inert gas pressure is 1 ± 0.2 bar.
3. Add 20 mL ultrapure water to the empty measuring vessel at
the 757 VA Computrace Stand.
4. Click on or MAIN WINDOW / Utility / Computrace control to
open the COMPUTRACE CONTROL window.
5. Select HMDE and click on .
6. Make sure that inert gas bubbles are purging through the so-
lution.
Check the stirring
1. Click on or MAIN WINDOW / Utility / Computrace control to
open the COMPUTRACE CONTROL window.
2. Select HMDE and click on .
3. Change the rotational speed by clicking on the buttons of
the RDE/stirrer speed field.
Check the MME
1. Install the MME at the 757 VA Computrace Stand (see Hard-
ware Manual).
2. Make sure that the inert gas pressure is 1 ± 0.2 bar.
3. Add 10 mL ultrapure water to the empty measuring vessel at
the 757 VA Computrace Stand.
4. Add 0.25 mL potassium chloride c(KCl) = 1 g/L (Metrohm
No. 6.2308.020) to the measuring vessel.
5. Click on or MAIN WINDOW / Utility / Computrace control to
open the COMPUTRACE CONTROL window.
6. Select DME and click on .
7. Mercury flows out of the capillary. The typical natural drop
time is in the range of 1 - 5 sec. If the natural drop time is
smaller than 0.5 sec, change the capillary and/or needle at
the MME (see Hardware Manual).