Overview
ISO 9553:1997 - "Solar energy - Methods of testing preformed rubber seals and sealing compounds used in collectors" specifies classification and laboratory test methods to evaluate rubbers and sealants used to seal solar collectors. It helps manufacturers, designers and test laboratories select and verify seal materials for service conditions (thermal cycling, UV/weathering, ozone, low temperature and adhesion). The standard covers material requirements, dimensional tolerances and detailed test procedures (including an Annex A adhesion test).
Key topics and technical requirements
- Classification of seals by service temperature (Types B…H) and by climatic class for low-temperature performance (W, M, C, P). Test and maximum service temperatures are given in the standard.
- Material expectations: seals must be UV resistant and free of defects that affect serviceability.
- Dimensions & tolerances: moulded and extruded seals must meet dimensional tolerance classes referenced to ISO 3302‑1 (e.g., moulding classes M2/M3, extrusion E2).
- Physical performance requirements (specified for preformed seals and sealing compounds), including:
- Hardness (IRHD) - test per ISO 48 or ISO 7619
- Tensile strength and elongation at break - ISO 37
- Compression set - ISO 815 (and ISO 1653 for low temperature)
- Resistance to heating (accelerated heat exposure per ISO 188 procedure)
- Volatile loss and condensables after heating
- Ozone resistance - ISO 1431‑1 (no cracking under defined strain/ozone concentration)
- Low‑temperature brittleness - ISO 812
- Adhesion testing (Annex A): an accelerated, application‑oriented method using immersion in water, cyclic compression/extension (±25% of joint width) at controlled temperatures, thermal soak steps and repeated cycles to detect bond loss or cohesive failure. Conditioning and sample preparation times are specified (e.g., 14–21 days conditioning).
Applications and users
- Practical uses:
- Specifying seals for flat-plate and evacuated-tube solar collectors
- Verifying material suitability for stagnation temperatures, daily thermal cycling, and outdoor exposure
- Quality control and acceptance testing of preformed seals and sealant compounds
- Typical users:
- Solar collector manufacturers and component suppliers
- Material formulators and rubber compounders
- Test laboratories and certification bodies
- Design engineers specifying sealing solutions for solar thermal systems
Related standards
- ISO 37, ISO 48, ISO 188, ISO 812, ISO 815, ISO 1431‑1, ISO 3302‑1, ISO 4661, ISO 4892‑2, ISO 877, ISO 471 - referenced for specific test methods and conditioning procedures. These are commonly used together with ISO 9553 when assessing long‑term ageing and weathering.
Keywords: ISO 9553:1997, solar energy, rubber seals, sealing compounds, solar collectors, test methods, adhesion test, compression set, ozone resistance, low‑temperature performance.