GE XMTC User Manual page 78

Appendix B. Typical Applications
B.2.7b Calibration
Refer to Chapter 4, Calibration, for the complete XMTC calibration procedure. The procedures below are only a
supplement to that procedure. These procedures show the valve configurations necessary to bring the calibration gases
to the XMTC.
Zero Gas Calibration:
1. Fully close N1 and/or N3.
2. Slowly open N2 until the sample outlet flowmeter reads mid-scale. The pressure gauge at the sample outlet
should read 0 psig.
Note:
If N3 was closed in this step and if the flow in the reference gas outlet flowmeter increased when N3 was
closed, adjust N4 to bring the flow to mid-scale.
Allow enough time for the tubing to be cleared of the sample gas or calibration span gas before making any
adjustments to the transmitter.
Span Gas Calibration:
1. Fully close N1 and/or N2.
2. Slowly open N3 until the sample outlet flowmeter reads mid-scale. The pressure gauge at the sample outlet
should read 0 psig.
Note:
If the flow in the reference gas outlet flowmeter decreased when N3 was opened, adjust N4 to bring the flow to
mid-scale.
Returning to Standard Operation:
1. Fully close N2 and/or N3.
Note:
If N3 was closed in this step and if the flow in the reference gas outlet flowmeter increased when N3 was
closed, adjust N4 to bring the reference gas flow to mid-scale.
2. Slowly open N1 until the sample outlet flowmeter reads mid-scale. The pressure gauge at the sample outlet
should read 0 psig.
After the system has come to equilibrium, the sample system should be checked periodically to insure that there is flow
through both flow meters.
68 XMTC User's Manual