Metrohm 746 VA Trace Analyzer - Manual (Page 45)

3 Installation
746 VA Trace Analyzer / 747 VA Stand
3-18
3.4.4 Filling the capillary without vacuum
The glass capillary 109 109 can normally be filled with mercury by the method de-
scribed here without vacuum. However, if difficulties regarding stability or repro-
ducibility arise with a capillary filled in this manner, try to fill the capillaries by the al-
ternative method with vacuum (section 3.4.5).
To fill the mounted glass capillary 109
109 (section 3.4.3) with Hg without vacuum, pro-
ceed as follows:
1 Install multi-mode electrode in 747 VA Stand
• With the measuring head arm 40 40 tilted back, slide the empty measuring
vessel 28 28 into the holder 26 26 of the 747 VA Stand and then lower the
measuring head arm 40 40.
• Carefully insert multi-mode electrode 38 38 in opening 76 76 of the measuring
head 41 41 (during insertion, the tip of the capillary 109 109 must not touch the
measuring head) and push in carefully as far as it will go. Avoid water
drops touch the tip of the capillary.
2 Connect multi-mode electrode
• Screw FEP tubing 51 51 for the inert gas supply into connection 93 93 of the
multi-mode electrode 38 38.
• Screw FEP tubing 59 59 for the inert gas supply into connection 94 94 of the
multi-mode electrode 38 38.
• Attach electrode cable 37 37 (WE) to screw connection 110 110 of the multi-
mode electrode 38 38: push cable lug under the screw and then tighten
screw firmly.
3 Fill capillary with mercury
• Switch on 746 VA Trace Analyzer with mains switch 11 11 (746 VA Trace
Analyzer and 747 VA Stand must first be installed properly as described
in section 3.2 and section 3.3).
• Select dialog page "STAND" and then switch on the inert gas supply to
the 747 VA Stand by pressing the softkey . This pressurizes
the multi-mode electrode 38 38 and the mercury begins to flow slowly out of
the capillary.
• Gently tap the MME with your finger (to remove any air bubbles) and
allow the mercury to flow out of the capillary into the empty measuring
vessel for approx. 2 min.
• Fill measuring vessel 28 28 with 10 mL ultrapure water and add 1 drop KCl
solution (in pure water, mercury drops from the capillary only with diffi-
culty).
• Allow mercury to flow out of the capillary for ca. 2 min while checking the
drop formation: The drop time should be ca. 3 s.
4 Adjusting the sealing needle 97 97
• Turn slotted screw 96 96 using a suitable coin slowly in a clockwise direction
until the mercury flow stops.
• Open slotted screw 96 96 slightly in an anticlockwise direction until the
mercury flow restarts.