Nova-Tech DO 6+ - Manual (Page 35)

Instruction Manual DO 6+
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6. PROBE MAINTENANCE
The DO 6+ probe is a galvanic measuring element which produces an output
proportional to the oxygen present in the medium in which it is placed. The
galvanic probe design lets you take measurements immediately – without the
typical 15 minute wait of polargraphic dissolved oxygen probes.
The probe consists of two parts. The upper part consists of the anode, cathode,
and dual cable. The lower part consists of a pre-assembled cap, and electrolyte
solution.
Oxygen diffuses through the membrane onto the cathode, where it is
consumed. This process produces an electrical current which flows through the
cable to the meter. The electric current produced is proportional to the oxygen
that passes through the membrane and the layer of electrolyte. This makes it
possible to measure the partial pressure of oxygen in the sample at a given
temperature.
Since the DO in the sample is consumed by the cathode it is essential to have
flow past the membrane of the probe to prevent the occurrence of false
readings. The probe uses very little oxygen for its measurement. This enables it
to function correctly with liquid movement as low as 2 inch/sec across
membrane.
The permeability of the membrane to oxygen varies greatly with temperature.
Therefore compensation is needed for this variation. The DO 6+ probe comes
with built-in temperature compensation for the membrane variation.
Proper maintenance will help you maximize probe life and accurate readings.
Deposits on the membrane surface act as a barrier to oxygen diffusing through
the membrane, so clean the membrane to assure maximum reliability.
After each use, rinse the probe with clean water to avoid any hardening of
deposits. If growth develops on the probe, use a disinfecting chemical to clean.
NOTE: Although the membrane is strong and not easily damaged, wipe it gently
while cleaning it. If the membrane is punctured, damaged, or torn, the probe will
not function properly.
There are no special probe storage requirements.