Owner manual

3.5 Reference electrode
757 VA Computrace – Hardware
37
3.5.2 Startup procedure
The reference electrode
22
is supplied in modular form as the reference system
101
and the electrolyte vessel
102
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 gas bubbles interrupt the electrical connec-
tion.
•
Hold reference system
101
so that diaphragm
108
faces upwards.
•
Unscrew diaphragm support
107
.
•
Fill electrolyte compartment
106
completely with the desired internal
electrolyte. Expel any air bubbles by tapping shaft gently.
•
Screw diaphragm support
107
back on, the electrolyte solution thus
displaced is expelled through the vent opening
104
.
2 Add bridge electrolyte
•
Fill internal compartment
110
of the electrolyte vessel
102
with a suitable
bridge electrolyte whose composition depends on the analyses to be per-
formed (aqueous or non-aqueous solution, composition of the supporting
electrolyte, etc.).
If you use the same solution for the bridge electrolyte and the internal
electrolyte (single-junction operation), the inner diaphragm 108 can
be omitted to reduce the electrical resistance: Unscrew diaphragm
support 107 with diaphragm 108 from the reference system 101.
3 Screw reference electrode together
•
Insert the filled reference system
101
in the vessel
102
filled with bridge
electrolyte and screw tight. The electrolyte solution thus displaced is ex-
pelled through the vent opening
109
.
4 Install reference electrode in 757 VA Computrace Stand and
connect
•
Insert reference electrode
22
in opening
58
of the measuring head
20
(see
Fig. 6
).
•
Attach electrode cable
27
(RE) to reference electrode
22
:
push cable lug under the screw and then tighten screw firmly.
•
Turn reference electrode
22
so that the electrode cable
27
points to the
rear and not to the side (in the latter position it may become kinked and
damaged when cover
1
is closed).
•
Wait approx. 20 min before first measurement (it takes some time for a
new reference electrode to become wet).