Metrohm 746 VA Trace Analyzer - Manual (Page 57)

3 Installation
746 VA Trace Analyzer / 747 VA Stand
3-30
3.6.2 Startup procedure
The reference electrode 43 43 is supplied in modular form as the reference system
122 122 and the electrolyte vessel 123 123 and has first to be filled and assembled as fol-
lows:
1 Add internal electrolyte
Filling of the reference system is necessary only when the optional
6.0728.010 Reference system supplied dry is used, if the internal electrolyte
solution has to be renewed or if the electrical connection is interrupted by
gas bubbles.
• Hold reference system 122 122 so that diaphragm 129 129 faces upwards.
• Unscrew diaphragm support 128 128.
• Fill electrolyte compartment 127 127 completely with the desired internal
electrolyte. Expel any air bubbles by tapping shaft gently.
• Screw diaphragm support 128 128 back on, the electrolyte solution thus
displaced is expelled through the vent opening 125 125.
2 Add bridge electrolyte
• Fill internal compartment 131 131 of the electrolyte vessel 123 123 with a suitable
bridge electrolyte whose composition depends on the analyses to be
performed (aqueous or non-aqueous solution, composition of the sup-
porting electrolyte, etc.).
If you use the same solution for the bridge electrolyte and the internal
electrolyte (single-junction operation), the inner diaphragm 129 129 can
be omitted to reduce the electrical resistance: Unscrew diaphragm
support 128 128 with diaphragm 129 129 from the reference system 122 122.
3 Screw reference electrode together
• Insert the filled reference system 122 122 in the vessel 123 123 filled with bridge
electrolyte and screw tight. The electrolyte solution thus displaced is ex-
pelled through the vent opening 130 130.
4 Install reference electrode in 747 VA Stand and connect
• Insert reference electrode 43 43 in opening 79 79 of the measuring head 41 41
(see Fig. 9).
• Attach electrode cable 48 48 (RE) to reference electrode 43 43:
push cable lug under the screw and then tighten screw firmly.
• Turn reference electrode 43 43 so that the electrode cable 48 48 points to the
rear and not to the side (in the latter position it may become kinked and
damaged when cover 24 24 is closed).
• Wait approx. 20 min before first measurement (it takes some time for a
new reference electrode to become wet).