Yokogawa PH18 Differential pH Sensor - Manual (Page 15)

15
IM 12B6J4-E-A
The probe can be cleaned/sterilized inside the
reactor. For CIP cleaning it must be ensured that the
admissible alkali and acid concentration as well as the
maximum temperature or cleaning time are not
exceeded. Otherwise, the enamel of the electrode
would be subject to increased corrosion.
NOTE: With alkali cleaning, corrosion is doubled with
every temperature jump of 10 ºC. The use of
oxidizing acids, such as HNO3, is limited to
solutions of 1.5% at a maximum of 50 °C.
6-1. Acceptable CIP cleaning processes
1. 1.5 - 2% alkaline solution, max 85 ºC, max 1 hour.
2. 1.5% acid (HNO3), 50 ºC, max. 15 min.
3. Steam 134 ºC, max. 2 hours
After cleaning with alkaline solution without acid and
steam sterilization, a transitional measuring error may
occur if the wetting time is too short.
6-2. Sterilization methods
The probe is resistant to the following sterilization
methods:
• with product
• with steam
• with alcoholic solutions
• with antiseptic solutions
The PH18 does not normally require maintenance, as
long as it is kept clean. Buffer checks may be done if it
is suspected that the sensor performance has
drifted appreciably. It is best, however, simply to do
a single point “Manual” calibration against a grab
sample taken at the process temperature and normal
pH value.
For cleaning or removal of residues dilute acids may
be used for a short time at room temperature only.
Limescale may be removed with commercially
available “antiliming” agents. The non-abrasive
material intended for ceramic cookers may be used to
remove sticky coatings from the PH18 -
Do not use
any metallic or abrasive substances!
6. CLEANING/STERILIZATION 7. MAINTENANCE