Overview
ISO 14952-2:2003 specifies cleanliness levels for surfaces in contact with fluids in space systems. It defines a common nomenclature and numeric/letter codes used to specify and verify the particulate, non‑volatile residue (NVR), and visible contamination requirements for components and equipment used in ground support equipment, launch vehicles and spacecraft. The standard supports consistent cleaning, analysis and verification of fluid-system hardware across programs and suppliers.
Key topics and requirements
- Classification of cleanliness levels: Cleanliness is described using discrete codes (e.g., particulate levels such as 200, 300; combined codes such as 200B; and NVR levels A…J). The code chosen is used to instruct cleaning centres and to label sealed packaging after verification.
- Three contamination types:
- Particulate contamination - defined by particle size ranges and maximum counts (presented in a tabular system).
- Non‑volatile residue (NVR) - specified as surface and volumetric limits tied to lettered levels.
- Visible contamination - qualitative visual categories (e.g., “visually clean”, UV‑inspected).
- Test methods: Six methods (I–VI) are defined by application:
- Method I - rinse test (small items, controlled environments)
- Method II - liquid flow test (hoses, tubing, assemblies)
- Method III - gas flow test for residual moisture
- Methods IV–V - system flow tests to evaluate delivery of clean fluids/gases
- Method VI - gas flow assessment after wet or brush cleaning of piping
The standard advises Methods I or II as default unless the customer specifies otherwise.
- Traceability and handling: After cleaning and verification, items must be sealed and labeled with the cleanliness code to preserve status during transport and integration.
- Basis and lineage: Particulate levels were derived from prior military/national criteria (e.g., MIL‑STD‑1246C) and empirical particle distributions.
Applications and users
ISO 14952-2 is used to:
- Specify acceptance criteria for fluid-system components (valves, filters, tubing, fittings).
- Define procurement and inspection requirements for contractors and cleaning centres.
- Guide QA, integration and contamination-control procedures for ground support equipment, launch vehicles and spacecraft.
Typical users:
- Aerospace design and systems engineers
- Manufacturing, cleaning and test facilities
- Quality assurance and procurement teams
- Contamination-control specialists and test laboratories
Related standards
- ISO 14952-1: Vocabulary
- ISO 14952-3: Analytical procedures for NVR and particulate determination
- ISO 14952-4/5/6: Cleaning and drying process guidance (coarse to fine)
- MIL‑STD‑1246C (historical basis for particulate levels)
Keywords: ISO 14952-2, surface cleanliness, space systems, fluid systems, cleanliness levels, particulate contamination, NVR, cleaning verification, ground support equipment, launch vehicles, spacecraft.
