Overview - What ISO 12629:2022 covers
ISO 12629:2022 defines a laboratory method for measuring the water vapour transmission properties of preformed pipe insulation used in building services and industrial installations. The standard specifies the apparatus, test specimen preparation, controlled test conditions and the steady‑state “dry cup” procedure (desiccant method) used to determine water vapour flow rate, water vapour permeance and derived properties such as water vapour permeability (δ) and the water vapour resistance factor (μ). It applies to thermal insulating products including homogeneous materials and products with integral skins or adhered facings.
Key topics and technical requirements
- Test principle: Desiccant-filled “dry cup” assembly placed in a controlled chamber; periodic weighings determine steady‑state vapour transmission.
- Environmental conditions: Chamber maintained at (23 ± 1) °C and (50 ± 3) % RH (air circulation recommended 0.02–0.3 m/s).
- Apparatus & materials:
- Desiccant: anhydrous calcium chloride (CaCl2), particle size 2–15 mm (or equivalent).
- Analytical balance: accuracy ±1 mg (or equivalent relative accuracy for larger assemblies).
- Aluminium foil: vapour‑tight, ≥50 µm with polymer face in contact with desiccant; suitable adhesive/sealant for vapour‑tight joints.
- Specimen preparation: Minimum length (100 ± 1) mm; for outer diameters >100 mm length ≥150 mm. Specimens must include skins or facings and be representative of the product.
- Sampling & repetition: At least five specimens if not otherwise specified; include one “dummy” specimen (no desiccant) to correct for non-diffusive weight changes.
- Results and calculations: Water vapour flow rate (G), flow density (g), permeance (W), resistance (Z), permeability (δ) and resistance factor (μ) - with procedures for calculation and reporting.
- Accuracy & reporting: Clauses define measurement accuracy and required test report contents.
Applications - Who uses ISO 12629:2022
- Manufacturers of preformed pipe insulation for product development, quality control and technical data sheets.
- Independent test laboratories and certification bodies performing performance verification and compliance testing.
- HVAC and mechanical engineers, specifiers, architects and building envelope consultants assessing condensation risk and specifying insulation for pipes in buildings and industrial systems.
- Regulatory authorities and procurement teams needing standardized vapour transmission data for compliance and comparative assessment.
Related standards
- ISO 12572 - Vapour transmission measurements (conversion tables and flat product methods)
- ISO 12628 - Dimensions and squareness of preformed pipe insulation
- ISO 29768 - Linear dimensions of test specimens
- ISO 9346 - Hygrothermal terminology and physical quantities
Keywords: ISO 12629:2022, water vapour transmission, preformed pipe insulation, water vapour permeance, water vapour permeability, μ‑factor, dry cup test, thermal insulating products.