Calibration Setup - Emerson Rosemount Analytical HART 5081-A-HT Instruction Manual

MODEL 5081-A

7.8 CALIBRATION SETUP

7.8.1 Purpose
This section describes how to do the following:
1. Enter stabilization criteria for calibration
2. Enter an upper limit for sensor zero
3. Enter a salinity value for air calibration of dissolved oxygen sensors
4. Enable dual slope calibration for free and total chlorine sensors.
7.8.2 Definitions
1. STABILIZATION CRITERION. The transmitter can be programmed not to accept calibration data until the reading has
remained within a specified concentration range for a specified period of time. For example, a stability criterion of
0.05 ppm for 10 seconds means that calibration data will not be accepted until the reading changes less than 0.05 ppm
over a 10-second period. The transmitter calculates the concentration using the present calibration data, or in the case
of a first time calibration, the default sensitivity.
2. SENSOR ZERO LIMIT. Even in the complete absence of the substance being determined, all amperometric sensors
generate a small current called the zero or residual current. The transmitter compensates for the residual current by
subtracting it from the measured current before converting the result to a concentration value. The zero current varies
from sensor to sensor. The transmitter can be programmed not to accept a zero current until the value has fallen below
a reasonable limit.
3. SALINITY (DISSOLVED OXYGEN ONLY). The solubility of oxygen in water depends on the concentration of dissolved
salts in the water. Increasing the concentration decreases the solubility. If the salt concentration is greater than about
1000 ppm, the accuracy of the measurement can be improved by applying a salinity correction. Enter the salinity as
parts per thousand (‰). One percent is ten part per thousand.
4. DUAL SLOPE CALIBRATION (FREE AND TOTAL CHLORINE ONLY). Free and total chlorine sensors from
Rosemount Analytical (Model 499ACL-01 and 499ACL-02) become non-linear at high concentrations of chlorine. Dual
slope calibration allows the analyzer to correct for the non-linearity of the sensor. For more information see Section
10.4 or 11.4.
7.8.3 Procedure
PROGRAM
Cal setUp
EXIT NEXT ENTER
PROGRAM
span Cal
EXIT NEXT ENTER
PROGRAM
stabilise
EXIT NEXT ENTER
PROGRAM
tIME
10
EXIT ENTER
42
1. Press PROG on the remote controller.
2. Press NEXT until the CAL SEtUP submenu appears. Press ENTER.
3. The screen displays the SPAn CAL prompt. To set the stabilization criteria, press
ENTER.
4. The screen displays the StABiLiSE prompt. Press ENTER.
5. Set the stabilization time between 0 and 99 seconds. The default value is 10 sec-
onds. Press ENTER to save.
PROGRAMMING
Procedure continued on following page.
SECTION 7.0