Honeywell Mini-AT, User Manual, Page: 64 / 156

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Page 64
Mini-AT User Guide
11) If the Mini-AT's absolute pressure reading is acceptable, click the “
Span” button to change to the
Span Calibration sequence.
12) The screen title should have changed to; "Pressure Span Calibration". At this point, the software is
waiting to sample the applied pressure that exceeds the zero reference pressure by at least 50% of
the rated pressure transducer range. Increase the pressure applied to the Mini-AT to the span
reference pressure.
Example #1; If the zero reference pressure on a 100 PSIA transducer equals 14.73 PSIA, then the span
reference pressure must be between 64.73 and 100.00 PSI.
Example #2; If the zero reference pressure on a 100 PSIA transducer equals 13.25 PSIA, then the span
reference pressure must be between 63.25 and 100.00 PSI.
Example #3; If the zero reference pressure on a 600 PSIA transducer equals 14.73 PSIA, then the span
reference pressure must be between 314.73 and 600.00 PSI.
13) The span calibration also displays a live pressure reading to allow the user to determine if the span
reference pressure has stabilized. When the absolute pressure has stabilized, click the “
Average
Pressure Now” button when it becomes active to obtain a pressure sample. NOTE; The span
reference pressure is equal to the sum of the dead weight tester pressure, plus the atmospheric
pressure obtained in step 9 above.
14) If the average absolute pressure reading is not equal to the sum of the reference pressure, plus the
atmospheric pressure, click the “
Change” button when it becomes active. Enter the pressure value
for the span reference pressure (see NOTE i n step 13 above). As the computer screen updates, the
Mini-AT will calculate the required span (gain), store this calculated value at Item Code 020,
display the new values for items 017 (414) and 020 (417), display the previous values at items 018
(415) and 021 (418) before returning to a live pressure reading. Obtain as many pressure samples
as necessary until an acceptable span pressure reading is displayed.
15) Compare the average absolute pressure reading to the span reference pressure. If the average
absolute pressure reading is equal to the sum of the applied pressure plus the atmospheric
pressure, the pressure calibration process is complete. As a suggestion, recheck the pressure zero
reading and any number of pressure points within the transducer range, or click “Done” to exit the
calibration sequence.