Emerson Rosemount FCL-01 Reference Manual page 48

Programming the transmitter
October 2023
Resolution
4.5.3 pH/ORP definitions
ORP
Redox
Preamplifier
Solution
temperature
correction
Resolution
Filter
Reference
impedance
4.5.4 Configure chlorine measurement
Complete the following steps to configure the transmitter to measure free chlorine.
Procedure
1. Press MENU.
2. Move the cursor to
48
relatively steady or subject to only seasonal changes, manual pH correction
is adequate.
If the chlorine concentration is less than 1.00 ppm (mg/L), the display
resolution can be set to
ORP is oxidation-reduction potential. It is the voltage difference between
a noble metal indicator electrode (like platinum) and a silver/silver
chloride reference electrode.
Redox is redox potential. It has the opposite sign from the ORP.
The pH signal has a high impedance. Before it can be used, it must be
converted into a low impedance signal. The preamplifier accomplishes
this task, and it can be located in either the transmitter or the sensor. In
the Rosemount FCL-02, the preamplifier is located in the transmitter.
The pH of a solution, particularly an alkaline one, is a function of
temperature. If the temperature changes, so will the pH, even though
the concentration of the acid or base remains constant. Solution
temperature compensation converts the pH at the measurement
temperature to the pH at a reference temperature (77 ° F [25 °C]).
Generally, solution temperature compensation is used only in the
determination of pH in condensate, feedwater, and boiler water in steam
electric power plants.
The pH display resolution is user selectable:
The transmitter applies a software filter to the raw voltage value coming
from the pH sensor. The filter reduces noise, but increases the response
time. See Chlorine definitions
Usually, the impedance of the reference electrode in a pH sensor is low.
However, a few pH sensors have high reference impedance, and the
transmitter must be told that the reference impedance is high. The pH
sensor used in the FCL-02 has low reference impedance.
The main Menu screen appears.
Program
or .
0.XX 0.XXX
for more information.
and press ENTER.
Reference Manual
00809-0100-3412
or .
XX.X XX.XX
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