Owner's manual

ManualsBrandsMetrohm ManualsSoftware797 VA Computrace

2 Installation

797 VA Computrace / Hardware-Manual 8.797.8001EN

can also lead to leakage of the MME, i.e. the mercury flow cannot be stopped any

more.

Proceed as follows:

1 Remove Multi-Mode Electrode from 797 VA Computrace Stand

• Unscrew FEP tubing 34 and 42 from the MME, disconnect electrode cable

20 from MME.

• Take Multi-Mode Electrode

21 out of measuring head 24 while gently tap-

ping the MME to knock off any mercury drops on the glass capillary into

the measuring vessel.

• Place Multi-Mode Electrode in a horizontal position in the electrode holder

92 (see Fig. 11-3).

2 Unscrew slotted screw 74

• Using a suitable coin, unscrew slotted screw 74 out of screw thread 76 un-

til the contact surface of the black O-ring at the Plexiglas wall (thin, black

stripe) is just visible below the metal thread.

3 Replace sealing needle 75

If problems with leaks arise owing to a worn, deformed or damaged sealing

needle, it must be replaced. Three spare needles are supplied separately in a

protective plastic package. After unpacking a needle, please avoid any contact

whatsoever with the needle tip. The spare needle

75 is installed as follows:

• Carefully pull old sealing needle out of PTFE membrane of the slotted screw

74.

• Carefully insert new sealing needle without tilting into the hole in the PTFE

membrane of the slotted screw.

NOTE: Do not touch the needle with bare fingers but use the plastic package

4 Dismantle old capillary

• Position Multi-Mode Electrode vertically in the electrode holder (see Fig. 11-

1).

• Undo retaining nut

86 completely by turning anticlockwise and lift up until

the lower part of the glass capillary

87 with the wide opening is visible.

• Gently tap the glass capillary to knock off any residual mercury in the wide

opening into the MME.

• Press the retaining nut downward with one hand and with your other hand

take glass capillary completely out of the mount.

5 Dispose of old capillary

• Connect filling tubing 93 with the tubing coupling 96 to the two gas wash

bottles

95 and the vacuum pump (see Fig. 10).

• Insert glass capillary

87 (capillary end) in the filling cone 94 of the filling

tubing.

• Remove mercury from capillary with the vacuum pump.

6 Replenish mercury if necessary

Proceed as described in section 2.3.2.