AVS 53rd International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuA

Paper VT-TuA5
Development of a New NIST Calibration Service Using the Comparison Method for Vacuum Gauges Spanning the Range 0.65 Pa to 130 kPa

Tuesday, November 14, 2006, 3:20 pm, Room 2000

Session: Extreme High Vacuum and Vacuum Metrology
Presenter: J.H. Hendricks, NIST
Authors: J.H. Hendricks, NIST
P.J. Abbott, NIST
J.E. Ricker, NIST
J.H. Chow, NIST
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A new calibration service based on a secondary pressure transfer standard spanning the pressure range from 0.65 Pa to 130 kPa (5 millitorr to 975 torr) is being developed at NIST. Vacuum gauges in this range are presently calibrated using the NIST Ultrasonic Interferometer Manometers (UIMs). However, many customers desire direct traceability to NIST but cannot justify the cost of the NIST UIM calibrations. These customers are typically using less accurate gauges, such as Thermal Conductivity Gauges@footnote 1,2@ (TCGs), or the newer combination type gauges that have 2 sensors combined with electronics that average or select which sensor is being utilized depending on the pressure being sensed. This new system under development is being designed to add a lower cost Comparison Method Vacuum Gauge Service that is currently not available to NIST customers. This service will follow a similar model of other calibration services where a lower cost, and less accurate service is offered to customers who do not require the lowest uncertainty possible. The comparison method utilizes a high accuracy transfer standard package that consists of a 133 Pa (1 torr) Capacitance Diaphragm Gauge (CDG), a 13.3 kPa (10 torr) CDG and a 130 kPa (975 torr) Resonance Silicon Gauge (RSG) all encased in a temperature controlled enclosure that is periodically calibrated against the NIST 160 kPa UIM and 140 Pa Oil UIM Primary Pressure Standards. The transfer standard package, and ultimately the Comparison Method Vacuum Gauge Service, is designed to have expanded uncertainties as low as 0.05 % from 1.33 kPa to 130 kPa (10 torr to 975 torr) and 0.3 % from 1.33 Pa to 1.33 kPa (0.01 torr to 10 torr).