ISO 15859-12:2004

Overview

ISO 15859-12:2004 defines composition limits, sampling procedures and test methods for carbon dioxide (CO2) used in space systems. It applies to CO2 (gaseous or liquid) intended for purging and pressurization of launch vehicles, spacecraft flight hardware and ground support equipment, and may be applied to CO2 influents. The standard sets verification requirements that ensure CO2 delivered to the flight vehicle interface meets agreed purity and water-content limits.

Key topics and technical requirements

• Composition limits
  • CO2 purity (volume fraction): minimum 99%
  • Water content: maximum 0.092 mg per litre of gas (measured at 21 °C and 760 mm Hg)
• Scope of application
  • Applies at the point the fluid enters the launch vehicle or spacecraft, or as specified in a technical agreement.
  • Covers gaseous and liquid CO2.
• Sampling plan requirements
  • A sampling plan must specify sampling points, procedures, frequency, sample size, number of samples, test methods and responsibilities.
  • Sampling frequency: annually or per supplier/customer agreement.
  • Sampling points: storage site or flight vehicle interface unless otherwise specified.
  • Sample quantity/number: one sample per storage container or as agreed; containers sampled shall not be refilled after sampling.
• Responsibility
  • Unless otherwise agreed, the supplier is responsible for sampling and verification.
• Gaseous sampling methods
  • Fill sample and storage containers concurrently from the same manifold; or withdraw from supply container without a pressure regulator between supply and sample; or connect container directly to analytical equipment (with pressure regulation to protect equipment).
  • Safety caution: CO2 is an asphyxiant-prevent high concentrations in confined spaces.
• Test and analysis methods
  • Purity: Orsat (volumetric absorption) analysis, gas chromatography, or aggregate impurity determination.
  • Water content: detector tubes, electrolytic hygrometer, dew‑point analyser, piezoelectric sorption hygrometer (accuracy ±0.1 cm3/m or 5% of reading, whichever greater), or metal-oxide-capacitor analysers.
  • Calibration gas standards and traceability to national institutes are recommended where required.

Applications and users

• Who uses it: spacecraft and launch systems engineers, ground support equipment (GSE) managers, CO2 suppliers, procurement and quality assurance teams, and analytical laboratories.
• Practical uses: verifying CO2 purity/water limits for safe pressurization and purge operations, supplier acceptance testing, pre-launch QA, and establishing compliant sampling/testing procedures across supplier–customer interfaces.

Related standards

• ISO 15859 (other parts) - fluid characteristics and test methods for space systems (e.g., Part 1 Oxygen, Part 2 Hydrogen, Part 3 Nitrogen, Part 10 Water, Part 13 Breathing air).