Metrohm 757 VA Computrace - Manual (Page 27)

3.3 Multi-mode electrode (MME)
757 VA Computrace – Hardware
23
3.3.2 Filling the MME with mercury
When handling mercury, it is necessary to take special precautionary
measures. These are described in detail in section 4.2.
All actions involving the electrode and mercury vessels must be
performed in or over the drip pan 92 supplied (see Fig. 10).
The Hg reservoir 82 of the multi-mode electrode 17 is filled with mercury of the
highest degree of purity (mass fraction w ≥ 0.99999) as follows:
1 Prepare multi-mode electrode
• Unscrew locking ring 74 from slotted screw 75 (this gray PVC ring is
needed only to remove the slotted screws 75 or 80, see section 3.3.7 and
section 3.3.9).
• Turn slotted screw 75 in or out of the screw thread 77 using a suitable
coin until the contact surface of the black O-ring at the Plexiglas wall (thin,
black stripe) is just visible below the metal thread 77.
• Remove the plastic cap used as a transport safeguard from the retaining
nut 87.
• Undo retaining nut 87 fully and remove from screw thread 83.
• Place multi-mode electrode 17 with the capillary opening facing upwards
in the electrode holder 93 (see Fig. 9).
90
91
92
17
93
Hg
Fig. 9: Adding the mercury
17 Multi-mode electrode
(6.1246.0020)
92 Drip pan (6.2711.030)
90 Syringe (6.2816.020) 93 Electrode holder
(6.2615.030)
91 Needle (6.2816.030)