Overview
ISO/TS 23657:2022 specifies an intermediate‑scale box test to assess the reaction-to-fire behaviour of sandwich panel building systems. It is a laboratory screening method intended for product producers to evaluate flame spread, smoke and gas development, and the propensity for flashover in a box-shaped assembly made of sandwich panels. This Technical Specification is designed to reduce the number of full small-room tests (ISO 13784-1) required for comparative screening and is not intended to assess structural fire resistance, facades, or self‑standing capability (the latter is covered by ISO 13784-1 and ISO 13784-2).
Key Topics and Requirements
- Test specimen geometry: internal box dimensions are specified (depth 1 680 mm, width 840 mm, height 840 mm; opening 300 mm × 670 mm) and panel layout/joints must represent in-service construction.
- Specimen construction: all joints, fixings, facings and decorative coatings present in practice must be reproduced.
- Enclosure: a non‑combustible enclosure surrounds the specimen to contain combustion products; walls/ceiling use calcium silicate boards and are externally reinforced to prevent collapse. A defined gap (50 mm ± 10 mm) is maintained between panel outer surface and enclosure interior.
- Ignition source: a propane gas burner filled with ceramic balls (opening ~170 mm × 170 mm × 145 mm) is used; burner heat output is controlled according to the specification (initial and subsequent power rates as stated in the TS).
- Instrumentation: surface thermocouples are applied at prescribed positions (17 positions including W1–W14 and C1–C3), and additional measurement equipment (data recorder, timing device, heat/smoke release measurements) is required.
- Test purpose and limits: the method is a screening tool for reaction-to-fire performance and flashover tendency; it is explicitly not for evaluating façade behaviour or full fire resistance.
Applications and Who Uses It
- Sandwich panel manufacturers - for comparative product screening and quality control.
- Fire test laboratories - to run standardized intermediate‑scale tests before larger account-level testing.
- Fire safety engineers and specifiers - to understand likely fire behaviour of panel systems and to support product selection.
- Regulatory bodies and certification schemes - as part of a test matrix for reaction-to-fire assessment.
Practical uses include early-stage product development, routine batch comparisons, and preliminary assessment of flame spread and smoke/gas generation under controlled conditions (to reduce reliance on more resource‑intensive ISO 13784-1 tests).
Related Standards
- ISO 13784-1 - Reaction to fire test for sandwich panel systems: Small room test (full assessment, includes self‑standing capability).
- ISO 13784-2 - Complementary methods for self‑standing structures.
- ISO 13943 - Fire safety vocabulary used for terms and definitions.
Keywords: ISO/TS 23657:2022, reaction to fire test, sandwich panel, intermediate-scale box test, flashover, propane burner, thermocouples, calcium silicate enclosure.