IM 12A06S01-00EN-P
32
6 OPERATION OF SC (Specific Conductivity)
6.1 SA11 quick setup
Select a Yokogawa specific conductivity sensor equipped with an ID-chip which is suitable
for the process. When connected to the SA11 and powered, part of the setup of the SA11
will be done automatically by reading the content of the ID-chip of the sensor. These are
sensor characteristics, factory calibration data, customer calibration data, diagnostics and
loggings of calibration and events. See sections 7 and 8 for details.
Other setups have to be done by the Yokogawa HOST system, for details see the belonging
User’s Manual.
6.2 Measurement setup
6.2.1 Parameter setting
The SA11 measures and calculates process parameters, for details see section 7.
The suitable measurement parameter(s) for display and process control can be set by the
Yokogawa HOST system, for details see the belonging User’s Manual.
6.2.2 Temperature setting
The SA11 measures process temperature in Celsius (ºC) or Fahrenheit (ºF). Setup of the
temperature unit is done by the Yokogawa HOST system, for details see the belonging
User’s Manual.
6.3 Cell constant & polarization
6.3.1 Cell constant
The SA11 device will be set automatically to the last calibrated cell constant value when
connected to the sensor. When sensor is used the first time this last calibrated cell
constant is the calibrated factory cell constant. This value is printed also on the label of
the sensor. Beware that the information on the label, printed in a cell constant unit cm-1,
can differ with the information displayed by the HOST due to the possibility to set cell
constant unit in cm-1 or m-1.
6.3.2 Polarization
Applying an electrical current to electrodes in solution may cause an accumulation of
ionic species near the electrode surfaces and chemical reactions at the surfaces. Thus, a
polarization resistance arises on the electrode surface, which may lead to erroneous results
as it is a parasitic component to the solution resistance. This effect is monitored by analyzing
the signal of the conductivity sensor. If the effect of polarization leads to a difference in
percentage from the actual value, the SA11 device will flag an error. Setting of percentage
from 0% up to 50% is done by the Yokogawa HOST system, for details see the belonging
User’s Manual.
6.4 Diagnostics
6.4.1 Device state
The operating mode of the SA11 is reflecting the device state. Except from the standard
operating mode there are four other modes:
• Sleep mode (all calculations disabled)
• Calibration
• HOLD
• Safely remove (this is not a function of Yokogawa HOST systems)