GE XMO2, User Manual

Page: 45 / 196

Field Calibration 4-3
September 2007
Required Calibration
Materials
To perform a field calibration, the following materials are required:
•
offset gas - for a one-gas %O
2
calibration
•
zero gas - for a two-gas %O
2
calibration and/or a 4-20 mA analog
output calibration
•
span gas - for a two-gas %O
2
calibration and/or a 4-20 mA analog
output calibration
Note:
Suggestions for suitable calibration gases are listed on the
XMO2
Calibration Sheet provided with your unit. Also, be
aware that the accuracy of the calibration will only be as good
as the accuracy of the calibration gas(es) used.
•
GE Sensing XMO2 Calibration Sheet
•
a sample system or individual components (e.g. flowmeter, needle
valve, pressure gauge, etc.) for introducing the calibration gas(es)
to the XMO2 transmitter at the required pressure and flow rate. See
Chapter 2,
Installation , for specific recommendations.
•
a multimeter/ammeter (for a 4-20 mA analog output calibration)
!WARNING!
Avoid using explosive gas mixtures as your XMO2
calibration gas(es).
Preparing for Field
Calibration
To prepare the XMO2 for a field calibration, refer to Figure 4-1 on
page 4-4 and perform the following preliminary steps:
1. Turn the power on and allow at least 30 minutes for the XMO2 to
reach temperature stability.
2. Loosen the set screw that locks the XMO2 cover in place, and
unscrew the cover.
IMPORTANT:
Remember to replace the cover after the field
calibration has been completed.
3. Refer to Figure 4-2 on page 4-4, and locate the following items:
•
calibration pushbutton (Switch S3)
•
zero/span selector (Switch S1)
•
terminal block TB1
Note:
If you plan to perform the field calibration at a computer
terminal via the XMO2’s RS232 digital output, you do not
need to access the above items. Skip Steps 1-2 above.