6. Logistics (Things to Keep in Mind)
Storage
The pH or ORP Electrode’s sensing end should never
be stored dry. Always maintain moisture at the
sensor and reference junction. Proper electrode
storage maximizes electrode performance and
extends electrode life. It is best to store electrodes
in clean containers with its storage bottle filled
with soaking liquid. Oftentimes a soaker bottle will
have a sponge or cotton ball in the bottom – the
purpose of the sponge is to maintain some solution
in the event of a spill. However, it is best to store the
electrode with solution present.
Do not store an electrode in deionized water - this
will cause ions to leach out of the pH glass sensing
bulb and the reference junction, destroying
the electrode over time. Improper storage will
cause the same type of issues mentioned in the
troubleshooting minor issues section mentioned
above.
After a few months of storage, check the condition
of the probe to detect any issues. If there is mold
or crystal formation, clean the probe and replace
the storage solution
Handling
During shipment it is possible for air bubbles to form
in the glass pH sensing bulb. The presence of such
a bubble can cause a host of problems on the meter
display ranging from inaccuracy to instability,
to no reading at all. To remove air bubbles,
shake the electrode’s sensing end down in the same
manner as a clinical thermometer until the bubble
is dislodged and the glass sensor bulb is filled with
solution. This is not an issue for ORP Electrodes.
Rinse electrodes with deionized water (distilled or
deionized water) before and after measuring
a sample. Blot the end of the electrode with
lint - free paper to remove excess water.
NOTE Never wipe or rub the electrode to remove
excess water - wiping can create static charges
that interfere with correct pH measurement.
Potential failure modes and causes
Cracked glass membrane:
Reading could be all over the range or none
Slope out of range:
Inaccurate reading: when slope becomes low, pH
becomes high in acid and low in base
Impedance out of range:
The pH response can become sluggish or non-stable
Biofouling:
The pH can become erratic
To Next Page
Loading...
