Thermo Fisher Scientific CyberScan PD 300 - Manual (Page 60)

Instruction Manual PD 300
9.5 Membrane/O-ring Replacement (Optional Procedure)
It is recommended only experienced service personnel can perform this procedure.
This procedure is OPTIONAL, and should only be performed if you have new membrane and
O-ring. You are also required to have a membrane installation tool. These items are available
as optional accessories in the Accessories section.
1. Pull off the probe guard. See figure on right.
2. Unscrew the membrane cap from the probe.
3. Hold the probe under hot running water and brush away the
white oxide on the cylindrical anode with a stiff plastic brush –
do not use metal cleaning material.
4. If the cathode has any deposits, remove them with a light
scouring powder. Do not polish the cathode.
5. Using the installation tool, unscrew and remove the membrane
lock from the membrane cap. See Figure 44.
6. Remove the membrane and O-ring. Discard both.
7. Rinse the membrane cap and membrane lock in tap water.
8. Install a new O-ring inside the membrane cap.
9. Install a new membrane. Make sure the membrane covers the
O-ring all around its circumference. See Figure 45.
Figure 43: DO Probe & its
various parts
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