GE XMO2, User Manual

Page: 47 / 196

Field Calibration 4-5
September 2007
One-Gas Field
Calibration
This simplified field calibration procedure uses a single (offset) gas to
recalibrate the XMO2. Then, the XMO2 compares the data from this
field recalibration to the original factory calibration data, and stores
the difference as an
Offset Curve .
The XMO2 is usually factory-programmed for the offset gas
pushbutton calibration method. The
Calibration Sheet shipped with
your unit specifies the recommended oxygen level (in %O
2
) for the
offset gas to be used. This is the same offset gas oxygen level that was
used for the factory calibration. If no offset gas %O
2
is specified on
the XMO2 Calibration Sheet, the factory calibration was done with
100% N
2
(0.00 %O
2
) and the field calibration should use the same
offset gas.
Choose one of the following offset gas field calibration methods:
•
pushbutton method
•
RS232 digital communication
Then, proceed to the appropriate section for instructions.
Pushbutton Method
To perform a pushbutton offset gas field calibration, complete the
following steps:
1. Verify that your XMO2 is configured for a one-gas calibration (see
Chapter 5,
Basic Programming , for details). This is the factory
default configuration for all units.
2. Using the sample system controls, stop the flow of sample gas to
the XMO2 inlet port and initiate a flow of the same offset gas
specified on the XMO2 Calibration Sheet. Establish the same flow
rate and pressure conditions used for the sample gas, and allow the
offset gas to flow through the XMO2 for at least three minutes.
3. Using Figure 4-2 on page 4-4 as a guide, locate the Calibration
Pushbutton (Switch S3). Depress the Calibration Pushbutton and
hold it down for 20 seconds. During this time, the green light
below the
Calibration Pushbutton will go out.
4. When the Calibration Pushbutton is released, the green light will
come back on and the XMO2 has been recalibrated.
You may now return the XMO2 to normal operation by using the
sample system controls to stop the offset gas flow and restart the flow
of sample gas.