Fluke Calibration 4322-SYS-NAVAIR, Service Manual

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4322
Service Manual
2-16
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Gauge and vacuum pressure measurement with the intrinsically absolute pressure
module (A150K): AutoZero tares the reading to zero gauge pressure at vent. At all
other pressures, the output is dynamically compensated for small changes in
atmospheric pressure measured by the barometer module.
•
Absolute pressure measurement with the intrinsically absolute pressure module
(A150K): AutoZero tares the absolute pressure reading to align with the barometer
module at vent. This tare is used for all subsequent measurements until the next vent
routine.
The BaroCheck feature also utilizes the stability of the barometer module to ensure
measurement performance at low pressure. The BaroCheck function compares the
outputs of the A150K pressure module and the barometer module at several points in the
atmospheric pressure range. If the pressure modules agree within the expected tolerance,
the BaroCheck function will compensate the output of the A150K pressure module by the
difference. If the pressure modules do not agree within the expected tolerance, one of the
components may be failing or exceeding measurement tolerance, so compensation will
not be applied and the Controller will alert the user to a potential measurement issue.
The BaroCheck function is recommended to be run at least once every 30 days. The
Controller keeps track of when BaroCheck has been run, and will indicate if 30 days has
been exceeded with a “BaroChk” indication in the top left of the Main menu.
The BaroCheck function can be performed by selecting “BaroCheck” under the
Calibration tab in the Settings Menu while in Advanced Mode. If the user selects to run a
test procedure or perform a calibration while the Controller is displaying the BaroCheck
indication, the operator will be prompted to first perform the BaroCheck routine. If more
than 35 days has passed since the last successful BaroCheck routine, the Controller will
force BaroCheck to be performed before proceeding with a test procedure or calibration.
Once initiated, the BaroCheck runs automatically. As the BaroCheck function runs, the
Controller prompts the user to cap the test port and asks to proceed. The Controller shows
that BaroCheck is in progress for approximately 15 to 45 minutes as it automatically sets
several test points and verifies measurement. The variation in time needed to complete
BaroCheck is influenced by the Controller temperature stability which is affected by how
the system has been warmed up and used prior to running BaroCheck. In some cases, the
process can take up to an hour. The Controller beeps three times at the conclusion of the
test to alert that the function is complete. When BaroCheck detects damage or an out of
tolerance condition, the Controller notifies the user to run the BaroCheck function again
or to check calibration of the A150K and barometer modules.
Emergency Pressure Relief
For emergency pressure relief, the red

key immediately vents all pressure and cancels
the test. When the red

key is pushed, the Controller closes any open menus and
returns to the Main menu.
The Controller has an automatic pressure relief function that releases pressure if it
exceeds the upper or lower pressure limits. If an over pressure occurs, the Controller
sounds an alarm for 8 seconds, aborts the test, and logs an event in the Event Log. In
addition, if the display is rotated to access the Pressure Transducer Modules and pressure
control is active, the Controller performs an automatic emergency pressure relief to
protect the user.
To recover from an over pressure, correct the over pressure condition and then cycle
Controller power.