3.3 Multi-mode electrode (MME)
757 VA Computrace – Hardware
33
6 Replace sealing needle
76
if need be
If problems with leaks arise owing to a worn, deformed or damaged sealing
needle
76
, this must be replaced. Three spare needles are supplied sepa-
rately in a protective plastic package. After unpacking a needle, please avoid
any contact whatsoever with the needle tip. The spare needle
76
is installed
as follows:
•
Carefully pull old sealing needle
76
out of PTFE membrane of the slotted
screw
75
.
•
Carefully insert new sealing needle
76
without tilting into the hole in the
PTFE membrane of the slotted screw
75
.
When the sealing needle
76
is changed, it is always necessary to
change the glass capillary
88
!
7 Replace sealing ring
85
if need be
•
If the sealing ring
85
is contaminated or damaged in any way, it must be
replaced for the subsequent assembly of the MME. Two new sealing
rings
85
are enclosed in the package with the 6.1226.030 glass capillar-
ies.
8 Reassemble MME
•
Screw slotted screw
80
using a suitable coin flush into screw thread
79
.
Do not turn so tightly that the cemented-in steel threaded ring
79
becomes loose and hence jeopardizes the tightness and safety of the
MME!
•
Using a suitable coin, screw slotted screw
75
into the screw thread
77
until the contact surface of the black O-ring at the Plexiglas wall (thin,
black stripe) is just visible below the metal thread
77
.
•
Place multi-mode electrode
17
with the opening
83
facing upwards in the
electrode holder
93
(see
Fig. 11-1
).
•
Insert insert ring
84
in opening
83
.
•
Push sealing ring
85
onto locking ring
86
and insert both in the opening
83
.
•
Screw retaining nut
87
by hand into screw thread
83
until a slight resis-
tance is felt.
9 Add mercury
Proceed as described in
section 3.3.2
.
10 Mount new capillary
Proceed as described in
section 3.3.3
.
11 Fill capillary
Proceed as described in
section 3.3.4
or
section 3.3.5
.
