Barometric Pressure - Emerson Rosemount Analytical HART 5081-A-HT Instruction Manual

MODEL 5081-A

7.11 BAROMETRIC PRESSURE

7.11.1 Purpose
This section describes how to do the following
1. Set the units for barometric pressure
2. Enter a pressure other than the calibration pressure for percent saturation measurements.
7.11.2 Definitions
1. BAROMETRIC PRESSURE. Because the current generated by an amperometric oxygen sensor is directly propor-
tional to the partial pressure of oxygen, the sensor is generally calibrated by exposing it to water saturated air. See
Section 9.1 for more information. To calculate the equivalent concentration of oxygen in water in ppm, the transmitter
must know the temperature and barometric pressure. This submenu lets the user specify the units for barometric pres-
sure.
2. PERCENT SATURATION PRESSURE. Oxygen is sometimes measured in units of percent saturation. Percent satu-
ration is the concentration of oxygen divided by the maximum amount of oxygen the water can hold (the saturation
concentration) at the temperature and pressure of the measurement. Generally, the pressure during the measurement
is assumed to be the same as the pressure when the sensor was calibrated. If the measurement and calibration pres-
sures differ, the measurement pressure can be entered as a separate variable.
PROGRAM
bar press
EXIT NEXT ENTER
PROGRAM
Unit
nnHG
EXIT ENTER
PROGRAM
% sat p
EXIT NEXT
PROGRAM
p man
760
EXIT ENTER
48
The barometric pressure submenu appears only if
the transmitter has been configured to measure oxygen.
7.11.3 Procedure
1. Press PROG on the remote controller.
2. Press NEXT until the bAr PRESS submenu appears. Press ENTER.
3. The Unit prompt appears. Press é or ê to scroll through the list of units:
nnHG mm Hg
1000PA kPa
Atn atm
bAr bar
InHG in Hg
Press ENTER to save.
4. If % saturation units were selected in Section 7.5, the % SAt P (saturation pressure)
prompt appears. Press NEXT.
5. Use the arrow keys to enter the desired pressure. The transmitter will use this pres-
sure to calculate percent saturation. Press ENTER.
6. Press RESET to return to the main display.
NOTE
SECTION 7.0
PROGRAMMING