ISO 20251:2016 PDF

Overview

ISO 20251:2016 specifies a laboratory water impermeability test for textile floor coverings (wall‑to‑wall installations). The standard defines a repeatable method to determine whether water penetrates through the product backing under controlled conditions. This test is not applicable to installed textile floor covering tiles; it is intended for laboratory evaluation of specimen samples.

Key topics and requirements

• Test principle: A coloured liquid is applied in a concentrated area on the specimen; after 24 hours the underside is inspected for liquid penetration.
• Test liquid: Methylene blue solution, 1 g/L (CAS 61‑73‑4).
• Apparatus: Open‑ended, non‑permeable cylinder, 110 mm diameter × 110 mm high (e.g., PVC).
• Specimens: Select 3 specimens per sample, minimum size 350 × 350 mm (selection per ISO 1957).
• Volume applied: 100 mL of the coloured liquid poured into the cylinder placed on the specimen surface.
• Conditioning and environment: Standard atmosphere for textiles - (65 ± 4)% relative humidity and (20 ± 2) °C (ISO 139).
• Timing: Specimens remain for 24 hours in the standard atmosphere before evaluation.
• Assessment: Inspect white tissue placed beneath each specimen for evidence of water penetration through the backing.
• Result expression: Record penetration/did not penetrate for each specimen. Declare the product water-impermeable only if none of the specimens show penetration.
• Test report: Must state conformity to ISO 20251 and include date, product identification, sample history, permeability result, and any deviations from the standard.

Applications and who uses it

ISO 20251 is useful for:

• Manufacturers of carpets and textile floor coverings for quality control and product development.
• Independent testing laboratories performing standardized permeability assessments.
• Specifiers, procurement teams and architects who need documented evidence of a product’s resistance to liquid penetration.
• Flooring certification bodies and compliance officers requiring objective test data for labeling or contract requirements.

Use cases include product acceptance testing, comparative product evaluation, and documentation of backing performance for wet‑area risk assessment.

Related standards

• ISO 139 - Standard atmospheres for conditioning and testing textiles (conditioning requirements).
• ISO 2424 - Textile floor coverings - Vocabulary (terms and definitions).
• ISO 1957 - Machine made textile floor coverings - Selection and cutting of specimens for physical tests (sampling).

Keywords: ISO 20251, water impermeability test, textile floor coverings, carpet water impermeability, methylene blue solution, standard atmosphere, laboratory test, backing penetration test.