Overview
ISO 27895:2009 - Vacuum technology - Valves - Leak test - defines standardized methods to leak-test vacuum valves used to control gas flow or vacuum pressure. It applies to valves that can be closed to leak rates below 1 × 10‑5 Pa·m3/s (trace gas) and specifies a sealing arrangement and test configurations for verification of valve specifications. The standard supports reproducible measurement of valve leak rates during and after operation so manufacturers and users can define operating pressure ranges, permissible pressure differences, bake-out/operating temperatures, and lifecycle expectations.
Key topics and technical requirements
- Test scope: Valve seat leak test and valve body leak test are the primary methods; optional tests cover pneumatic pressure extremes, manual torque extremes, operating temperature range and post‑bake testing.
- Leak types: Distinguishes real leaks, virtual leaks (outgassing/trapped volumes) and permeation leaks (through materials). Virtual leaks are not measurable by the methods in ISO 27895.
- Trace gas & detectors: Mass‑spectrometer‑type leak detectors (typically helium) are used. Detectors must be calibrated to a standard leak (see ISO 3530) and have detection limits better than the valve’s nominal leak rate.
- Test configurations: Multiple port‑connection configurations (four main setups) for seat testing; a hood filled with trace gas at ~100 kPa for body testing. A probe method is available for qualitative/comparative measurements.
- Environmental & procedural controls:
- Ambient temperature: (23 ± 7) °C.
- Sealing surfaces must be clean and dry.
- Detector warm‑up, tuning and calibration required; waiting times for measurement must minimize permeation effects (typically <30 s where practical).
- Helium mixtures should have a controlled helium fraction (>10% recommended) and measured values corrected for volume fraction where necessary.
Practical applications and users
- Who uses ISO 27895:
- Vacuum valve manufacturers (type testing, delivery inspection, specification verification)
- Independent test laboratories and quality assurance teams
- Vacuum system designers and integrators in industries such as semiconductor manufacturing, research labs, vacuum coating, particle accelerators and analytical instrumentation
- Procurement and maintenance engineers specifying acceptance criteria and in‑service verification
- Why it matters: Standardized leak testing enables consistent valve selection, reliable system performance, correct specification of operating limits (pressure, temperature, differential), and predictable valve lifetime behavior.
Related standards
- ISO 3530 - Vacuum technology - Mass‑spectrometer‑type leak detector calibration (normative reference cited in ISO 27895).
