10
1 9 2 5 R o u t e 5 1 , J e f f e r s o n H i l l s , P A ,
1 5 0 2 5
8 0 0 . 2 4 5 . 1 6 5 6 w w w . l e s k e r . c o m
Notes on calibration
The instrument is calibrated in nitrogen, which has thermal properties virtually identical to air. Other
gasses will affect the readings by an amount proportional to the thermal conductivity of the gases. In
most cases, the gases present in a vacuum system will be air, nitrogen, or oxygen, and no
appreciable errors will occur.
Certain other gases, however, have thermal conductivity significantly greater than air and will cause
the instrument to read higher than the actual amount of pressure.
Examples of such gases are water vapor, fluorocarbon refrigerants, and acetone. Conversely, other
gasses have thermal conductivity significantly lower than air and will cause the instrument to read
lower than actual pressure. Examples of such gases include helium, oxygen and to a lesser extent,
CO2.
When interpreting readings using gasses other than air, it should be borne in mind that the
Vacuum
Gauge
reads absolute pressure—that is the opposite of vacuum. Thus, a lower numerical reading
actually is a higher level of vacuum.
Section 10: Accuracy
Instrument Repeatable Accuracy
Range
Accuracy
1~99 millitorr
+/- 2 millitorr or 20%
100~1000 millitorr
+/- 15%
Section 11: Specifications
Time to resolve
2 seconds to decade, 20 seconds to full accuracy
