Instructional manual- HBPH-MK2
– UK-004
Page 6
1.
Disconnect the red wire at the instrument or power supply and connect it to the multimeter (-)
black.
2.
Connect the multimeter (+) red to the instrument or power supply red wire output terminal.
3.
Rinse the probe and place it in 7 pH buffer. Allow the temperature of the buffer and probe to
stabilize at room temperature.
4.
Check the offset of the probe by reading the multimeter. The reading should be between 11 and
13 mA. If not, the probe is defective, or the salt bridge needs to be replaced. If the offset is OK,
please note the exact reading and proceed to the next step.
5.
Rinse the probe and place it in 4 pH or 10 pH buffer. Allow the temperature of the probe and
buffer to stabilize at room temperature. Now check the span of the probe by reading the
multimeter. If the probe is in 4 pH buffer, the reading should be between 2.75 and 3.5 lower than
the reading obtained in 7 pH buffer.
6.
If the probe is in 10 pH buffer, the reading should be between 2.75 and 3.5 higher than the reading
obtained in 7 pH buffer.
7.
If this test is not satisfied the probe is defective, or the salt bridge needs to be replaced.
8.
If the span of the probe drops below 2.75mA than the probe still can be used. Adjustments will
have to be made to the receiving device to compensate for the low span.
Probe Cleaning
The probe should be kept reasonably clean to avoid measurement errors. Frequency of cleaning can only
be determined by experience.
To
clean proceed as follows:
1.
Rinse with clean warm water.
2.
Soak the end of the probe in warm water and dish detergent for 3 or 4 minutes.
3.
Brush the end of the probe, particularly the three electrodes with a soft bristle brush such as a
toothbrush. Take care not to scratch the glass electrode.
4.
If the probe is still not clean, it may have to be cleaned with acid.
CAUTION: Do not acid clean
probes used in processes containing cyanide solutions.
Some experimentation may be required to
determine the most suitable acid for your process. Use the most dilute acid, which is effective.
Normally 10 parts of water to one-part muriatic acid (HCl) is sufficient.
Do not use hydrofluoric
acid.
5.
Soak the probe for not more than 5 minutes in the chosen acid; then rinse thoroughly with clean
warm water and soak in water for 3-5 minutes.
6.
Calibrate the system in accordance with the instrument instruction manual.