5
DISSOLVED OXYGEN PROBE,
continued
Maintenance
Membrane cap replacement and refilling are required at scheduled
intervals or if the probe does not function properly, e.g. in the case of a
damaged membrane or contaminated DO probe. If the membrane is not
damaged, the recommended time interval for replacing the Electrolyte
Filling Solution is 1-2 months.
Note: Hach supplies a
DO probe service kit
that includes one
50-mL bottle of
Dissolved Oxygen
Electrolyte Filling
Solution, two
Membrane Module
Caps and a
Polishing cloth.
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 replacements if the performance of the probe seems to
have degraded over time.
BOD Measurement
Adapt the Model 51970 Dissolved Oxygen Probe for BOD
measurements using the BOD Accessary Kit (Cat. No. 51971-00). The
kit includes a funnel and spacer that fit the Model 51970 DO Probe and
a standard 300 mL BOD bottle. The funnel has a stir bar incorporated
into the end which, when used with a stir stand, creates the proper
stirring motion required for BOD measurement. The spacer positions
the DO probe properly in the funnel. The funnel allows for sample
displacement with insertion of the DO probe and limits exposure to
atmospheric oxygen. Consult the sens
ion
6 Dissolved Oxygen Meter
Instruction Manual for more information.
Barometric Pressure Correction
The values presented in Table 1 are based on the assumption that the
barometric pressure at sea level is 760 mm Hg. Use Table 1 to
determine the barometric pressure at specific elevations or obtain the
current barometric pressure from a local weather service. See the
sens
ion
6 Dissolved Oxygen Meter Instruction Manual for specific
calibration instructions when using Table 1.
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