Maintenance
Calibration
6
6-11
6-5.bmp
Figure 6-5. Zero Set
Absolute Instruments
A vacuum pump must be connected to the reference port.
A vacuum gauge should be installed for measuring the case reference pressure. This
gauge should be installed as close to the sensor as possible. There is an 1/8-inch NPT
fitting available for this installation inside the PPI near the sensor
1.
Select the desired pressure units using the UNITS key. You can change both the unit
of measure that the PPI is displaying, Pressure, and the unit of measure, for the
vacuum sensor. It is not required to have the PPI 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 MENU | CALIBRATE.
3.
Select Zero [F1]. Do NOT press the Calibrate button. When initiating the zeroing
command in the PPI, 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 PPI 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 PPI would also increase if zeroed at higher
vacuum levels.
4.
Wait for the vacuum level on the test port to stabilize.
5.
Press OK [F6].
6.
Do not disturb the instrument while zeroing is in process.
7.
Wait for the zeroing procedure to finish.
8.
Press PREVIOUS to return to the Main Menu.
Summary of Contents for RUSKA 7050
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