ISO 16900-9:2015

Overview - ISO 16900-9:2015 (Respiratory protective devices, CO2 in inhaled gas)

ISO 16900-9:2015 specifies standardized test methods for measuring the increase of carbon dioxide (CO2) in the inhaled gas that results from wearing respiratory protective devices (RPD). It applies to complete devices or parts intended to meet RPD performance standards and excludes closed‑circuit supplied breathable‑gas RPD. This part of the ISO 16900 series supplements performance standards by defining equipment, procedures and reporting for CO2 testing.

Key technical topics and requirements

• Scope and exclusions: Measurement of CO2 increase in inhaled gas; closed‑circuit supplied breathable gas RPD are excluded.
• Test methods: The standard defines three test methods (summarized in sections 7–8) for different apparatus arrangements and measurement approaches.
• Apparatus and instrumentation (section 7): Requirements for a breathing machine / metabolic simulator, carbon dioxide analyser, CO2 sampling, RPD headform/torso, inhalation/exhalation reservoirs and test gases.
• Test procedures (section 8): Guidance on test sequences, breathing machine settings, operation, auxiliary fans, baseline adjustments when supplied gas is used, data acquisition and calculation of CO2 increase.
• Measurement quality and reporting: Test report content requirements and application of measurement uncertainty (Annex A) and informative material on CO2 concentration profiles and verification volumes (Annex B).
• Normative references: Uses ISO 16972 for definitions, and aligns with other parts of ISO 16900 for related test methods and equipment.

Practical applications and users

Who uses ISO 16900-9:2015:

• Manufacturers of respirators and facepieces - to design, verify and document that CO2 rebreathing is acceptable for intended uses.
• Test laboratories and certification bodies - to perform standardized CO2 inhalation tests for product certification and regulatory compliance.
• Occupational health & safety professionals and product developers - to assess user comfort, safety and performance related to CO2 accumulation in RPD.
• Regulators and standards committees - to reference consistent test methods in performance requirements for PPE.

Practical use cases:

• Routine type testing and quality control of filtering facepieces, full/half masks and other RPD.
• Comparative evaluation of design changes that affect dead space, breathing resistance and CO2 clearance.
• Supporting conformity assessment and safety documentation required by performance standards.

Related standards

• ISO 16900 series - other parts covering inward leakage, breathing resistance, filter penetration, breathing machines and consolidated tests (e.g., ISO 16900‑5, ISO 16900‑13).
• ISO 16972 - terminology and units used for RPD testing.

Keywords: ISO 16900-9:2015, respiratory protective devices, CO2, inhaled gas, test methods, breathing machine, carbon dioxide analyser, RPD testing, PPE certification, measurement uncertainty.