Here is the procedure for DO membrane replacement:
- Rinse the probe in water and wipe clean.
- Unscrew the cap and rinse the probe internals with water
- Inspect the anode (U shaped piece bolted to probe). Clean off any loose white deposits with a non-metallic brush (toothbrush). DO not scrape the anode with any metallic object.
- Unscrew the retaining ring using a coin or membrane cap as follows:
Unscrew the retaining ring using a coin.
Remove the old membrane and O-ring. Rinse with water and wipe dry.
Install a new O-ring and membrane.
NOTE: The O-ring must be installed first with the membrane place on top of it.
Screw in the retaining ring and tighten firmly. After installation the membrane must be flat - if it wrinkles remove it and try again until the membrane is taught and flat. Turning the membrane over often helps. If not replace with a new one.
NOTE: A membrane can only be used once. A membrane cap should not be re-used without replacing the membrane and O-ring. When a membrane cap is screwed onto the probe, the membrane is stretched by the cathode. If the same cap and membrane is used s second time it will not fit perfectly onto the cathode and will result in erratic readings, and will not fit perfectly a second time.
- Fill a new membrane cap to the brim with electrolyte, and fit to the upper part by holding the upper part with the vent hole away from you. Engage the cap with the upper part and slowly screw the cap into place without turning backwards at any time. Ensure that the large O-ring seats properly. Excess electrolyte should dribble out of the vent hole.
- Tighten the cap firmly by hand.
When calibrating the probe, you must install the DO calibration adapter, otherwise you will get the 'defective probe' error.
Curt
