Yokogawa PH18 Differential pH Sensor - Manual (Page 11)

11
IM 12B6J4-E-A
3. THE TYPE 18 PH PROBE
3-1. Typical applications
• Fermentation
• Continuous reactions
• Production of diary products
• Product monitoring
3-2. Handling information for the glass
lined pH probe.
The differential pH probes are pressure and thermal
shock resistant due to the fused steel/enamel
construction. The probes have a very high mechanical
stability and are extremely strong.
Inappropriate handling, e.g. hitting and scratching the
probe on steel, ceramics, glass or stone may cause
damage to the probe. Depending on the scope of the
damage, the probe may not fail immediately but
rather when the temperature changes. If a defective
measuring probe remains in aqueous solutions for
prolonged periods of time enamel may flake.
Enable the EXA impedance monitoring. If sensor
damage is indicated, the measuring probe must be
immediately removed (within 24h) after an alarm
message. All probes for use in the food sector are
tested with a voltage of 12 kV and conditioned for 5
hours in steam at a temperature of 134 °C.
3-3. Storage and hydration
The PH18 Probe can be stored dry for an indefinite
period of time at temperatures between -30 and +80
ºC. After prolonged storage or if this is a new probe
from the factory a simple steam sterilization should
be performed for 15-30 minutes prior to calibration.
This procedure revitalizes the probes giving it a stable
reference potential. If steaming is not possible soak
the PH 18 for 45-60 minutes in hot water (65 to 85 ºC).
If steaming or a hot soak can not be done, place the
Probe in a standard pH7 Buffer solution for 24 hours
prior to installation. The probe must be immersed
so that both measuring elements are covered with
buffer.
3-4. Installation
Procedure:
1. Remove the probe from the packaging, remove the
protective plastic hose and carefully introduce the
probe into the nozzle.
2. Fasten probe with union nut
3. Connect cable. For this purpose, loosen the heavy
gauge conduit connection at the protective plastic
cover, push out the connector, put the connector in
the proper position, and firmly press it into the
female connector of the probe (water- tight
interlock). Push the protective cover and O ring
sealing onto the probe until the stop and tighten the
heavy gauge conduit connection again manually.
4. The cable with high temperature stability (blue) must
be fastened vibration free. The cable must not be
laid together with power cables.
Only suitable transmitters with symmetrical
high impedance inputs may be used. The
following units are approved:
• Yokogawa EXA PH 202
• Yokogawa EXA PH 402w