Overview
ISO 15859-3:2004 - "Space systems - Fluid characteristics, sampling and test methods - Part 3: Nitrogen" defines composition limits, sampling plans and test methods for nitrogen used in space systems. The standard covers both gaseous (Type I) and liquid (Type II) nitrogen across grades for purging/pressurizing, crew breathing and specialized uses. It applies to fluids at the flight-vehicle interface or storage points and is intended to verify nitrogen purity before entry into launch vehicles or spacecraft.
Key topics and technical requirements
- Composition limits: Specifies permitted impurity levels (water, total hydrocarbons, oxygen, hydrogen, argon, CO₂, CO, aromatic/halogenated/chlorinated hydrocarbons, particulates and total impurities) and examples of nitrogen purity requirements (ranging up to >99.99% for higher grades).
- Types and grades: Distinguishes Type I (gaseous) and Type II (liquid) nitrogen and multiple grades (e.g., Grade A for purging/pressurizing, Grade B for crew breathing).
- Sampling plan: Requires an approved sampling plan specifying sampling points, procedures, frequency, sample size and responsibilities. Sampling is typically at storage or flight-vehicle interface and is performed annually or per agreement.
- Sampling methods: Describes safe methods for gaseous sampling (simultaneous filling, withdrawal without intermediate regulators, or direct connection to analyzers) and for liquid sampling (collecting representative liquid and vaporizing for analysis).
- Test and verification methods: Allows direct and indirect purity measurement. Accepted analytical techniques include gas chromatography (e.g., 5Å zeolite columns), mass spectrometry, flame‑ionization detectors for total hydrocarbons, dew-point and sorption hygrometers for water, electrochemical/paramagnetic/zirconia oxygen analysers, and other calibrated detectors.
- Rejection rules: Fluids failing verification tests must be rejected; disposal and corrective actions are determined by the customer.
- Safety: Notes asphyxiation risk of gaseous nitrogen and severe cold injury from liquid nitrogen - handling and storage safety required.
Applications
- Pre-launch verification of nitrogen used for purging, pressurizing, thermal systems, and ECLSS (environmental control and life support systems).
- Quality control at spaceports, launch sites, ground support equipment, propellant and pressurant supply chains.
- Supplier acceptance testing and contractual verification between nitrogen suppliers and launch/spacecraft integrators.
Who should use this standard
- Space agencies, launch service providers and prime contractors
- Ground support and launch-pad engineers
- ECLSS and life-support system designers and test labs
- Gas suppliers, quality assurance teams and analytical laboratories performing gas purity testing
Related standards
- Other parts of ISO 15859 (Part 1: Oxygen; Part 2: Hydrogen; Part 4: Helium; Parts 5–13 for other fluids)
- ISO 9000 (quality management vocabulary and fundamentals)
Keywords: ISO 15859-3, nitrogen purity, space systems, sampling and test methods, gaseous nitrogen, liquid nitrogen, launch vehicle, gas chromatography, mass spectrometer, dew-point analyser.
Open preview (PDF)Space systems — Fluid characteristics, sampling and test methods — Part 3: Nitrogen
