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Indicated vs. true total pressure (test gases N
2
, Ar, He)
Gas Correction Chart
The Y- axis of the above chart is actual pressure as measured
by a capacitance manometer, a diaphragm gauge that measures
true total pressure independent of gas composition. The X-axis
is the pressure reading indicated by the convection gauge under
test. This chart shows readings for an INFICON convection
gauge (CVG) and Granville-Phillips® Convectron® gauge to
illustrate that the difference in the response for both of these
types of gauges is virtually indistinguishable.
CAUTION!
Do not assume this data applies to other convection
gauges which may or may not be the same. Refer to the table in
section 6.1 and note the following examples:
Example A: If the gas is nitrogen (N
2
), when the true total pres-
sure is 500 Torr, the gauge will read 500 Torr.
Example B: If the gas is argon (Ar), when the true pressure is
100 Torr, the gauge will read about 9 Torr.
If you are backfilling your vacuum system with Ar, when your
system reaches a pressure of 760 Torr true pressure your gauge
will be reading about 23 Torr. Continuing to backfill your system,
Summary of Contents for 3PE5-001-B7HZ
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