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www.thinkSRS.com 1
SRS Bayard-Alpert Gauge Calibration
Service
Stanford Research Systems has established a High Vacuum Calibration Facility to generate
high-accuracy, NIST-traceable, full-range calibrations for any new BAG operated with an SRS IGC100
controller. Two accuracy levels are available: a 6% accuracy full-range calibration and a high-precision
3% accuracy full-range calibration.
All calibration information generated at the SRS High Vacuum Calibration Facility is returned to the user
in a 'memory card' that can be used to transfer the calibration data, including all necessary instrument
setup information, into any IGC100 controller. With the calibration data transferred into the controller,
any IGC100 can accurately measure and display unknown pressures in real time over the entire useful
range of the BAG.
In This Application Note
Introduction 3
Sensitivity Factor 3
Full-range calibration 4
Who Needs to Calibrate a BAG? 5
Calibration Storage in the IGC100 6
SRS High Vacuum
Calibration Facility 7
Calibration at a
Standards Laboratory 10
Important Terms 12
References 13
(408)744-9040 Stanford Research Systems
www.thinkSRS.com
2 SRS Bayard-Alpert Gauge Calibration Service
Stanford Research Systems (408)744-9040
www.thinkSRS.com
SRS Bayard-Alpert Gauge Calibration Service 3
Introduction
The calculation of pressure with a Bayard-Alpert gauge (BAG) relies on the knowledge
of the gauge sensitivity factor, Sg, which is strongly dependent on (1) gauge geometry,
(2) gas type and, to a lesser extent, (3) pressure and (4) emission current1. Once the
sensitivity factor is known, the pressure, P, is calculated from the simple mathematical
expression:
P = [ Ic / (Sg