Aalborg XFM Digital - Manual (Page 27)

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7.2.2 ZERO Check/Adjustment
Using Aalborg® supplied calibration and maintenance software open Back Door
access:
Query/BackDoor/Open
When software prompts with Warning, click the [YES] button. This will open the
access to the rest of the Query menu.
Start Sensor Compensated Average reading:
Query/Read/ SensorCompAverage
This will display Device Sensor Average ADC counts.
With no flow conditions, the sensor Average reading must be in the range 120±
10 counts. If it is not, perform Auto Zero procedure (see section 5.3.10 “Zero
Calibration”).
7.2.3 Gas Linearization Table Adjustment
Gas flow calibration parameters are separately stored in the Gas Dependent por-
tion of the EEPROM memory for each of 10 calibration tables. See APPENDIX I
for complete list of gas dependent variables.
The XFM gas flow calibration involves building a table of the actual flow values
(indexes 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134) and correspon-
ding sensor readings (indexes 113, 115, 117, 118, 119, 121, 123, 125, 127, 129,
131, 133).
Actual flow values are entered in normalized fraction format: 100.000 % F.S. cor-
responds to 1.000000 flow value and 0.000 % F.S. corresponds to 0.000000 flow
value. The valid range for flow values is from 0.000000 to 1.000000 (note: XFM
will accept up to 6 digits after decimal point).
Note: Your XFM Digital Mass Flow Meter was calibrated at the factory
for the specified gas and full scale flow range (see device’s front label).
There is no need to adjust the gas linearization table unless linearity
adjustment is needed, flow range has to be changed, or new additional
calibration is required. Any alteration of the gas linearization table will
VOID calibration warranty supplied with instrument.
Note: Make sure the correct gas number and name selected are
current. All adjustments made to the gas linearization table will be
applied to the currently selected gas. Use Gas Select command via
digital communication interface (see paragraph 8.3 ASCII Command
Set “XFM SOFTWARE INTERFACE COMMANDS”) or Aalborg®
supplied calibration and maintenance software to verify current gas
table or select a new gas table.