ISO 15859-9:2004

Overview

ISO 15859-9:2004 - Space systems - Fluid characteristics, sampling and test methods - Part 9: Argon specifies purity limits, sampling requirements and test methods for argon (Ar) used in space systems. It applies to both gaseous (Type I) and liquid (Type II) argon used for purge and pressurization of launch vehicles, spacecraft, and ground support equipment. The standard defines verification procedures to ensure argon delivered to the flight vehicle interface meets compositional and water-content limits.

Key Topics and Requirements

• Composition limits (when tested per the standard):
  • Argon, minimum 99.985%
  • Oxygen, maximum 0.005%
  • Hydrogen, maximum 0.005%
  • Nitrogen, maximum 0.005%
• Water content: ≤ 0.02 mg H2O per litre (measured at 21.1 °C and 101.3 kPa) or dew point ≤ −53.8 °C.
• Scope: Applies to influents entering the launch vehicle/spacecraft and to any sampling operation required to verify composition.
• Sampling plan: Operators must establish and approve a plan that specifies sampling points, procedures, frequency, sample size and number, test methods, and responsibilities.
• Sampling responsibilities: Unless otherwise specified, the supplier is responsible for sampling and verification at the flight vehicle interface.
• Sampling rules: Typical sampling at storage site or flight interface; annual sampling or as agreed; one sample per storage container or other agreed number; gaseous samples obtained without intervening regulators; liquid samples vaporized before analysis.
• Rejection: Any sample failing tests per Clause 7 must result in rejection of the represented fluid.
• Test methods: Multiple accepted analytical techniques for each parameter:
  • Purity/aggregate impurities: thermal conductivity analyzer, gas chromatography (GC), mass spectrometry (MS)
  • Water: dew-point analyzers, piezoelectric sorption hygrometers, metal-oxide-capacitor analysers, electrolytic hygrometers
  • Oxygen, nitrogen, hydrogen: electrochemical analyzers, heat-of-reaction devices, spectrophotometric/ion-current techniques, GC or MS
• Annex A: Recommends GC (or GC-MS) as reference for impurity analysis; provides detector guidance.

Applications - Who uses this standard

• Launch providers and spacecraft integrators for purge and pressurization requirements.
• Gas suppliers and cryogenic handlers to set procurement and verification procedures for argon.
• Ground support and test laboratories performing composition and moisture analysis.
• Quality, procurement and system engineering teams drafting technical specifications or acceptance criteria.

Related Standards

ISO 15859 is a multipart series covering fluids for space systems (e.g., Part 1 Oxygen, Part 2 Hydrogen, Part 3 Nitrogen, Part 4 Helium, Part 10 Water, etc.). Refer to adjacent ISO 15859 parts for harmonized sampling and testing practices across different spacecraft fluids.

Keywords: ISO 15859-9:2004, argon purity, space systems, gas sampling, test methods, gaseous argon, liquid argon, purge and pressurization, gas analysis, GC-MS.