Overview
ISO 9808:1990 - "Solar water heaters - Elastomeric materials for absorbers, connecting pipes and fittings - Method of assessment" defines a harmonized method to evaluate elastomeric (rubber and similar) materials used in solar water heating systems. The standard specifies which mechanical, chemical and ageing tests are required to assess suitability and durability of materials exposed to heat, ozone and heat-transfer fluids (e.g., propylene glycol). ISO 9808 helps manufacturers, test labs and specifiers ensure materials will perform reliably in absorber plates, connecting pipes and fittings.
Key topics and requirements
- Scope of assessment: Characterization and performance tests for elastomeric components used in solar water heaters (absorbers, pipes, fittings).
- Mechanical properties:
- Hardness (preferably ISO 48 method).
- Tensile strength and elongation at break (ISO 37 using dumb-bell specimens).
- Tear resistance (ISO 34-1, crescent specimen).
- Pressure performance:
- Burst/pressure-eclatement testing for pipes and absorber components per ISO 1402; minimum specimen lengths specified.
- Low-temperature compression set:
- Permanent deformation after compression: small-specimen test at −40 °C with 25% compression for 24 h (ISO 1653).
- Ozone resistance:
- Procedure A of ISO 1431-1 for flat specimens (7 days at ~200 ppm ±20 ppm ozone, 40 °C ±2 °C, 20% elongation); ISO 7326 procedures apply for pipes and absorbers.
- Artificial ageing:
- Oven ageing per ISO 188 for 14 days at test temperatures selected according to maximum service temperature (classification types provided); specimens conditioned after ageing per ISO 471.
- Chemical compatibility / immersion tests:
- Immersion in propylene glycol (if used) per ISO 1817 (7 days) or in the proposed heat-transfer fluid when applicable.
- Reporting:
- Test report format specifying properties before and after ageing and immersion (hardness, tensile, elongation, burst pressure, ozone state, compression set, tear).
Applications and users
- Material selection and validation for solar water heater manufacturers (absorbers, hoses, seals, fittings).
- Component suppliers and rubber compound formulators verifying long-term performance in heat-transfer fluids and outdoor conditions.
- Independent test laboratories, product certifiers and procurement teams specifying acceptance criteria and preparing technical dossiers.
- R&D teams evaluating new elastomeric compounds for resistance to heat, ozone and glycol-based fluids.
Related standards (referenced)
- ISO 1431‑1 (ozone cracking), ISO 1653 (compression set), ISO 1817 (liquid action), ISO 34‑1 (tear), ISO 37 (tensile), ISO 48 (hardness), ISO 188 (ageing), ISO 471 (conditioning), ISO 1402 (hydrostatic/burst testing), ISO 4661‑1 (sample preparation), ISO 7326 (ozone testing for pipes/absorbers), ISO 4632‑1 (temperature classification).
Keywords: ISO 9808:1990, solar water heaters, elastomeric materials, ozone resistance, ageing tests, propylene glycol compatibility, burst pressure, material assessment.
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