| AVS 62nd International Symposium & Exhibition | |
| Vacuum Technology | Monday Sessions |
| Session VT-MoM |
| Session: | Vacuum Measurement, Calibration, and Primary Standards |
| Presenter: | Jacob Ricker, National Institute of Standards and Technology |
| Authors: | J.E. Ricker, National Institute of Standards and Technology J. Hendricks, National Institute of Standards and Technology |
| Correspondent: | Click to Email |
The most frequently measured pressures are those in the barometric regime. These measurements are used for everything from altimetry to weather and significant resources have been spent in the past couple years improving barometric measurements. Recent improvements in devices covering this range have drastically reduced their uncertainties, making 0.01% or lower very common. However for vacuum measurement (100 kPa > P > 0.01 Pa), most often people use the capacitance diaphragm gauges (CDG) for their resolution and ability to reach the lower pressures. The capacitance gauges are very prone to drift making uncertainty of 0.25% an average expectation for performance for a high end device. However, by pairing a capacitance gauge to a barometric sensor to compare the values at 1 kPa, a CDG can be corrected to reduce the uncertainty to as low as 0.05%. This technique will be incorporated into the NIST Portable Vacuum Standard (PVS) reference instrument that can be provided for calibration of vacuum gauges at a customer’s facility.
Key to this concept is the accuracy and uncertainty of the barometric sensor. NIST has been evaluating measurement methods by taking different high accuracy barometric gauges into the vacuum regime. We have shown that less than 0.05% is easily achievable at 1 kPa and might be even be achievable at 0.1 kPa. The results will be presented for different gauge types, measurement methods, and manufacturers. The talk will include discussions on accuracy, noise, and stability and an uncertainty estimation of using this technique.