Hanna Instruments HI 4105 - Manual (Page 5)

8 9
•
If sensor has been stored or shipped dry, it should be
“conditioned” by soaking the pH/reference assem-
bly 1 hour or more in one of the pH test solutions.
•
Avoid touching the pH glass with your fingers.
•
Attention: The pH/reference assembly is fragile!
Support the upper portion of the internal cell while
immersing the glass and reference assembly. A tall
narrow container with weighted bottom is best. The
pH test solution should cover the bottom of the large
black band.
Test: Connect the BNC connector on the electrode cable to a
pH/mV (mV or ORP mode) meter. Carefully immerse
the sensor assembly into one of the buffers. When the
measurment stabilizes record the mV generated. Rinse
sensor tip in deionized water and dab dry between
buffers to prevent solution carry-over. Do not rub the
glass. Take a measurement in the second buffer and
record mV. Pay attention to minus sign if present.
Calculate the difference in mV between the two solutions.
Example of typical values:
HI 4000-47- 7 -90.2 mV
HI 4000-47-4 80.66 mV
Difference 170.8 mV= 80.6-(-90.2)
A calculated value equal or greater than 160 mV is ac-
ceptable for ambient temperatures between 20
° and 25°C.
VIII. VIII. VIII. VIII. VIII. Inner Electrode Check Inner Electrode Check Inner Electrode Check Inner Electrode Check Inner Electrode Check
Prior to assembling the electrode for the first time first time first time first time first time or
subsquently reactivating it after extended periods of dry
storage, the inner electrode assembly should be hydrated
and then tested as a pH electrode.
Prepare pH test solutions HI 4000-47-4 and HI 4000-47-
7 by mixing and dissolving each buffer packet in separate
containers with 50 mL deionized water. These pH solutions
contain chloride ions and pH buffers that are used to verify
the inner electrode (pH internal) is operational. See
Section XVII for replacement accessories and maintenance
items.
For a new sensor:
Remove the protective shipping cap from the glass inner
electrode.
For existing sensor:
Unscrew the upper cap on the top of the electrode and
carefully withdraw the internal pH/reference assembly.
Use test
tube or
graduated
cylinder
(weighed
Bottom) when
testing or
conditioning
pH internal
Test buffer
can be
used as a
conditioning
solution
for the
pH internal
Protective shipping cap
For stable readings, glass should be covered to the
bottom of the long black band.