Procedure - Air Calibration - Emerson Rosemount Analytical HART 5081-A-HT Instruction Manual

MODEL 5081-A
9.3 PROCEDURE — AIR CALIBRATION
1. Remove the sensor from the process liquid. Use a soft tissue and a stream of water from a wash bottle to clean
the membrane. Blot dry. The membrane must be dry during air calibration.
2. Pour some water into a beaker and suspend the sensor with the membrane about 0.5 inch (1 cm) above the
water surface. To avoid drift caused by temperature changes, keep the sensor out of the direct sun.
3. Monitor the dissolved oxygen reading and the temperature. Once readings have stopped drifting, begin the
calibration. It may take 10 -15 minutes for the sensor reading in air to stabilize. Stabilization time may be even
longer if the process temperature is appreciably different from the air temperature. For an accurate calibration,
temperature measured by the sensor must be stable.
CALIBRATE
Sensor Cal
EXIT NEXT ENTER
CALIBRATE
A ir Cal
EXIT NEXT ENTER
CALIBRATE
nnHG
EXIT NEXT
CALIBRATE
Press
760 . 0
EXIT ENTER
CALIBRATE
time delay
EXIT ENTER
CALIBRATE
Cal dOne
EXIT
4. Press CAL on the remote controller.
5. Press NEXT. The SEnSor CAL submenu appears. Press ENTER.
6. The Air CAL prompt appears. Press ENTER.
7. The screen shows the units selected for barometric pressure. Press
NEXT.
8. Use the arrow keys to enter the barometric pressure. Press ENTER.
Be sure to enter the actual barometric pressure. Weather
forecasters and airports usually report barometric pressure
corrected to sea level; they do not report the actual baro-
metric pressure. To estimate barometric pressure from alti-
tude, see Appendix A.
9. The tiME dELAy message appears and remains until the sensor read-
ing meets the stability criteria set in Section 7.8. To bypass the time
delay, press ENTER.
10. This screen appears when the calibration is complete. The concentration
shown in the main display is the solubility of atmospheric oxygen in
water at ambient temperature and barometric pressure. Press EXIT.
11. To return to the main display, press RESET.
12. During calibration, the transmitter calculates the sensitivity (nA/ppm) of
the sensor. To check the sensitivity, go to the main display. Press DIAG.
Press NEXT until the SenSitvty (sensitivity) prompt appears. Press
ENTER to display the sensitivity in nA/ppm. Typical values at 25°C are
given in the table.
Sensor
499ADO
499ATrDO
Hx438 and Gx448
NOTE
nA/ppm
1,800 - 3,100
3,600 - 6,100
4.8 - 9.8
SECTION 9.0
CALIBRATION — OxyGEN
53