Overview
ISO 24477:2022 - "Vacuum technology - Vacuum gauges - Specifications, calibration and measurement uncertainties for spinning rotor gauges" - defines terms, technical specifications, calibration procedures and uncertainty evaluation for spinning rotor gauges (SRGs). Applicable up to 2 Pa, the standard supports accurate pressure measurement and the dissemination of the vacuum pressure scale for high and medium vacuum applications.
Key topics and technical requirements
The standard covers component definitions, required parameters and operational limits for SRGs, including:
- Terms & definitions for SRG components (rotor, thimble, suspension head, controller, flange assembly) and physical parameters (accommodation factor, effective accommodation factor σeff, residual drag, deceleration rate, offset).
- Essential specifications such as rotor diameter and density, rotor/thimble materials, flange and thimble leak rate, suspension head positioning, limits of rotor frequency, warm‑up period (typically 3–6 h), baking temperature, measurement range (to 2 Pa), sampling time, internal volume, interfaces, dimensions, display and electrical requirements, operating and storage conditions.
- Optional specifications like long‑term instability, expected measurement uncertainty, rotor–suspension compatibility, inspection records, allowed vibration, cable length and photographic documentation.
- Calibration: parameters to be calibrated, defined calibration procedures (including methods for determining effective accommodation factor σeff), how to assess calibration uncertainty, and required content for a calibration certificate.
- Measurement uncertainty at use: guidance on which uncertainty components to consider during routine SRG operation and on the determination of residual drag (to be found prior to measurement at pressures below the SRG’s lower measuring limit).
Applications and who uses it
ISO 24477:2022 is intended for:
- Calibration laboratories and national metrology institutes performing SRG calibrations and pressure‑scale dissemination.
- Manufacturers of vacuum gauges and SRG components specifying design, interfaces and performance limits.
- Quality managers, vacuum systems engineers and researchers in semiconductor, thin‑film deposition, surface science, and R&D where reliable high/medium vacuum pressure measurement is required.
- Metrologists assessing measurement uncertainty and producing traceable calibration certificates for SRGs.
Practical benefits include improved consistency in SRG specifications, reproducible calibration methods for the accommodation factor, and standardized treatment of measurement uncertainties for reliable vacuum measurement up to 2 Pa.
Related standards
ISO 24477:2022 complements and references:
Keywords: ISO 24477:2022, spinning rotor gauge, SRG, vacuum gauges, calibration, measurement uncertainty, accommodation factor, residual drag, vacuum technology.
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