Calibration; Nominal Cell Constants For 245 Sensors; Figure 1-2 Figure 1-2 245 Junction Box With Rtd Diagram - Emerson Rosemount 245 Instruction Manual

245 Sensor
June 2017
Figure 1-2 245 Junction Box with RTD Diagram (use of optional kit PN 24086-00 is
recommended)
1.5

Calibration

Before starting the calibration, enter the nominal cell constant into the analyzer. See Table
1-1. The accuracy of the nominal cell constant is probably no better than 10%. For greater
accuracy, calibrate the sensor.
Table 1-1 Nominal Cell Constants for 245 Sensors
1.5.1 Calibration against a standard solution
1. Obtain a suitable conductivity standard. If the sensor is being used to measure a broad
range of conductivity, choose a standard in the midpoint of the operating range.
Otherwise, choose a standard near the expected process conductivity.
2. Attach a blank flange to one end of the sensor. Stand the sensor on the sealed end.
3. Decide whether temperature correction is needed.
a. If the conductivity of the standard as a function of temperature is known, configure
the analyzer to measure raw conductivity (no temperature correction). Also, obtain
a calibrated thermometer. Place the thermometer in a beaker of water next to the
sensor. DO NOT PUT THE THERMOMETER IN THE SENSOR.
b. If the conductivity of the standard is known only at 25 ºC, leave the analyzer slope
temperature correction on and set the temperature coefficient to the appropriate
value. If the temperature coefficient is not given, consult the manufacturer of the
standard. Also, obtain a calibrated Pt 100 RTD and connect it to the analyzer. See
Wiring Diagrams. Place the RTD in a beaker of water next to the sensor. DO NOT PUT
THE RTD IN THE SENSOR
4. Fill the sensor with standard. Be sure no air bubbles are sticking to the liner and the sensor
is completely filled.
5. Wait for the standard and the water in the beaker containing the thermometer or RTD to
come to thermal equilibrium.
6. Refer to the analyzer instruction manual and adjust the analyzer display to match the
conductivity of the standard at either the temperature of the standard (step 3a) or at 25 ºC
(step 3b).
4
Sensor Size Nominal Cell Constant
½"
1"
1.5"
2"
8
2
1.6
1.3
Instruction Manual
LIQ-MAN-245
245 Sensor