Aalborg XFM Digital - Manual (Page 20)

17
5.3.6 K Factors Settings
Conversion factors relative to Nitrogen for up to 36 gases are stored in the XFM
(see APPENDIX II). In addition, provision is made for a user-defined conversion
factor. Conversion factors may be applied to any of the ten gas calibrations via
digital interface commands.
The available K Factor settings are:
• Disabled (K = 1).
• Internal Index The index [0-35] from internal K factor table
(see APPENDIX II).
• User Defined User defined conversion factor.
5.3.7 Zero Calibration
The XFM includes an auto zero function that, when activated, automatically
adjusts the mass flow sensor to read zero. The initial zero adjustment for your
XFM was performed at the factory. It is not required to perform zero calibration
unless the device has zero reading offset with no flow conditions.
Shut off the flow of gas into the Digital Mass Flow Meter. To ensure that no seep-
age or leak occurs into the meter, it is good practice to temporarily disconnect the
gas source. The Auto Zero may be initiated via digital communication interface or
locally by pressing the maintenance push button, which is located on the right side
of the flow meter inside the maintenance window above the 15 pin D-connector
(see Figure c-1 “XFM configuration jumpers”).
To start Auto Zero locally, press the maintenance push button. The status LED will
flash not periodically with the RED light. On the XFM with optional LCD, the fol-
lowing screen will appear:
Note: The conversion factors will not be applied for % F.S.
engineering unit.
Note: Before performing Zero Calibration, make sure the device is
powered up for at least 15 minutes and absolutely no flow condition is
established.
Note: The same maintenance push button is used for Auto Zero
initiation and Totalizer reset. The internal diagnostic algorithm will
prevent initiating Auto Zero function via the maintenance push button
before the 6 minutes sensor warm up period has elapsed.