60
SECTION 5,
continued
6. Use a clean lab wipe to blot the moisture from the electrode
anode and cathode.
7. Thread the membrane cap assembly loosely onto the body of
the probe.
8. Replace the membrane protector on the membrane cap.
5.5.4
Maintenance
Membrane cap replacement and refilling are required at
scheduled intervals or whenever the membrane has been damaged
or fouled. If the membrane is not damaged or fouled, the
recommended time interval for replacing the electrolyte filling
solution is 1–2 months.
Prior to replacing a membrane cap, rub the anode (the outer
metallic stem of the probe that is visible when the membrane cap
is removed) with the polishing cloth supplied with the probe.
The polishing cloth will remove deposits that may decrease the
performance of the probe. Polish the anode whenever the
membrane cap is replaced or between membrane cap
replacement, if probe performance seems to have degraded over
time.
5.6
Using the BOD Accessory Kit
The optional BOD Accessory Kit, which includes an overflow
funnel with a built-in stirring bar, serves three purposes:
•
The kit eliminates the need to retrieve magnetic stirring bars
from BOD sample bottles.
•
The funnel provides an overflow reservoir to hold sample
displaced when the DO probe is inserted in the bottle.
This permits the measurement to be made without spilling the
sample. When the DO probe is withdrawn, the displaced
solution can drain back into the bottle.
•
The funnel is designed to act as an electrode holder. This kit
is designed for use with Hach Model 51970 DO probe only.
