GB/T 45856-2025Vacuum technology - Vacuum gauges - Specifications, calibration and measurement uncertainties for Pirani gauges (English PDF)

GB/T 45856-2025 is the English-translated version of 真空技术 真空计 皮拉尼真空计的规范、校准和测量不确定度.

GB/T 45856-2025 establishes the parameters of Pirani vacuum gauges, describes their calibration procedure and specifies the measurement uncertainties to be considered when such gauges are used; clause 1 limits it to Pirani vacuum gauges with an operating pressure range of 0.01 Pa to 150 kPa, and adds that the document supplements ISO 3567 and ISO 27893 when Pirani gauges are calibrated and used as reference standards and that it also describes a method for characterising their response time and hysteresis.

The index shows clause 5 giving the Pirani vacuum gauge principle and clause 6 the specifications, in seventeen subclauses running from general principles and the measurement principle through output type, output range and output display resolution, measuring range and full scale, expected measurement uncertainty, materials exposed to gases, connecting flange, interface and pin connection, warm-up time, compatibility of the vacuum gauge tube and the control unit, normal operating (environmental) conditions, power supply, cable length and maximum baking temperature to the dimensions of the regulator and control unit and the installation direction.

Clause 7 adds eleven optional specifications, among them long-term instability, the relative sensitivity coefficient, hysteresis, response time, inspection records and calibration certificates, storage and transportation conditions, maximum power consumption and the pressure set point.

Clause 8 covers calibration and other measurement steps, including the calibration conditions, the installation and adjustment of calibration objects, the calibration itself, the measurement uncertainty during calibration, the calibration certificate and the procedures for measuring hysteresis and response time, while clause 9 deals with measurement uncertainty in use and the informative Appendix A shows typical Pirani vacuum gauges.

Clause 2 arrives truncated in the draft: the heading of its first entry is lost, only ISO 27893 is printed in full, and its notes point to GB/T 34873-2017, GB/T 34876-2017 and GB/T 27025-2019.

Clause 3 is split into component definitions and physical parameter definitions, and the draft shows only two of them, one whose term name is not printed, defined as a vacuum gauge that determines pressure by measuring the heat transfer between two fixed surfaces maintained at different temperatures and sourced from ISO 3529-3:2014, 2.4.2.2 with its examples deleted, and Pirani vacuum gauge, whose definition as shown speaks of the heating element forming part of a Wheatstone bridge circuit that provides energy to the element and measures the resistance or the power it dissipates.

The draft breaks off inside 3.1.2, so no clause text after that entry is shown.

The document is an identical adoption of ISO 19685:2017, was proposed by the China Machinery Industry Federation and is under the jurisdiction of the National Technical Committee on Vacuum Technology Standardization (SAC/TC18), and its introduction notes that Pirani vacuum gauges are widely used to measure pressures from medium vacuum up to atmospheric pressure.

The page records no earlier edition that it replaces; it was issued on 1 August 2025 and has applied since 1 November 2025.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 30 pages — is available in the English PDF.

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