Fluke RUSKA 7252, User Manual

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RUSKA 7252
Users Manual
6-12
glb46.bmp
Figure 6-5. Zeroing in Progress
6. Press PREVIOUS to return to the Main Menu.
Absolute Instruments
A high capacity vacuum pump must be connected to the rear reference port connector.
Units that were purchased with the Vacuum Sensor option, have an internal vacuum
sensor mounted internal to the primary sensor housing that monitors the vacuum level
when the instrument is being zeroed in the absolute mode. This sensor reading will
display a value of 350 mtorr when the vacuum level is at or greater than 350 mtorr.
1.
Select the desired pressure units using the Units key. You can change both the unit
of measure that the Calibrator is displaying Pressure and the unit of measure for the
vacuum sensor. It is not required to have the Calibrator displaying pressure in the
same unit of measure as the vacuum sensor. To change the unit of measure for the
Vacuum sensor, press the Unit key and then the Vacuum [ F2 ] key.
2. Enter the Calibration screen by selecting [MODE] MENU | CALIBRATE .
3. Select Zero [ F1 ]. Do not press the Calibrate button. When initiating the zeroing
command in the Calibrator, it will cycle the internal valves allowing the external
vacuum pump to pull a hard vacuum on the RUSKA sensor. It is recommended that
the sensor be pulled down to a vacuum of less than 200 mTorr (preferably less than
100 mTorr) in order to obtain a proper zero. The Calibrator can be zeroed at higher
vacuum levels, however, the uncertainty of vacuum sensors tend to increase at higher
vacuum levels, therefore, the uncertainty in the Calibrator would also increase if
zeroed at higher vacuum levels.
4. Wait for the vacuum level to stabilize as read by the internal vacuum sensor.
5. Verify that the primary sensor pressure and temperature are stable.
6. Press OK [ F6 ] when stable.
7. Do not disturb the instrument while zeroing is in process.
8. Wait for the zeroing procedure to finish.
9. Press PREVIOUS to return to the Main Menu.