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HVG-2020B Instruction Manual
temperature. The span error cannot be eliminated, but is typically less than 0.2 % of reading above 10 Torr and
typically less than 2% of reading below 10 Torr over -20 to 70 °C.
Pirani and Gas Interactions
While the Piezo operates independently of any gas, the Pirani is affected by different gases. To allow for
accurate measurement of vacuum in a specific gas, there are six pre-defined gases with the option for two
custom gases. The values for the pre-defined gases are not variable, but the custom gas options can be
changed using the R9 and R10 commands when a custom gas is selected. The custom gas values can also be
used to perform a calibration in the actual gas as described in Section 4.7.
Gas Name
Gas Factor
Nitrogen
1
Air
0.999
Helium
1.089
Argon
1.512
Hydrogen
0.656
CF4
1.015
SF6
0.913
Custom 1
1
Custom 2
1
Calibration Procedure
NOTICE: The HVG-2020B is calibrated in nitrogen at the factory and any attempt to adjust the values
associated with it will void the calibration.
Nitrogen Calibration
The HVG-2020B calibration requires digital communication. See Section 5.
1. Attach the HVG-2020B to a vacuum system and pump down below 0.0001 Torr
2. Make certain the instrument has been warmed up for 2 hours before proceeding.
3. Unlock the instrument by typing FLOK=1234
4. Set the temperature to ambient temperature near the gauge if necessary: TEMPSET=##.#
5. Zero the instrument by sending the ZRO command.
6. Backfill with nitrogen to between 0.1 and 1 Torr. Set the Pirani mid value equal to the value indicated
by the pressure reference: RMID = 0.###
7. Backfill with nitrogen to between 20 and 50 Torr. Set the Pirani high value equal to the value indicated
by the pressure reference: RHIGH = ##.##
8. Backfill with nitrogen to atmospheric pressure. Set the instrument span to equal the value indicated by
the pressure reference: SPAN=###.#
EAR99 Technology Subject to Restrictions Contained on the Cover Page
Gas Bend Factor
1
1.052
-0.676
0.881
-0.545
2.853
0.4327
1
1
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