3 Installation
757 VA Computrace – Hardware
30
3.3.6
Storing the MME
On completion of the measurements, the MME is stored in the 757 VA Computrace
Stand so that the tip of the glass capillary
88
is immersed in pure water (or in the
solvent used). This prevents blockage of the capillary by crystallized salts.
An electrode treated in this manner can be taken out of the 757 VA Computrace
Stand after a few hours and stored in air for a lengthy period without suffering any
damage. Always store the MME so that the glass capillary
88
is horizontal (see
Fig.
11-3
).
3.3.7
Replenishing the mercury (without changing capillary)
The multi-mode electrode
17
can also be refilled with mercury without having to re-
move the glass capillary
88
.
1 Dismantle multi-mode electrode
•
Unscrew FEP tubing
30
and
38
from the MME. Disconnect electrode
cable
16
from the MME.
•
Take multi-mode electrode
17
out of the measuring head
20
and tap the
MME gently to knock off any mercury drops on the glass capillary into the
measuring vessel.
•
Place multi-mode electrode
17
horizontally in the electrode holder
93
(see
Fig. 11-3
). The slotted screw
80
is now at the top.
2 Replenish mercury
•
Unscrew slotted screw
80
using a suitable coin. If the slotted screw
80
can not be loosened by hand, screw on locking ring
74
and pull out of
the MME.
•
Draw up mercury using the syringe
90
with attached needle
91
and expel
into the Hg reservoir
82
.
The Hg reservoir
82
must never be filled more than
2
/
3
full with mer-
cury.
•
Reinsert slotted screw
80
into screw thread
79
and screw flush to surface
using a suitable coin (this action may expel a few drops of mercury from
glass capillary
88
).
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!
