Overview
EN ISO 7231:2023 (adopted by CEN as EN ISO 7231:2023) defines standardized laboratory methods for determining the air flow value at a constant pressure-drop across flexible cellular polymeric materials (flexible foams). The standard specifies two main routes:
- Method A - for conventional flexible cellular polymeric materials (those not intended for sealing), and
- Method B - for all types, with special focus on low-air-permeability materials; Method B is split into B1 (manual measurement) and B2 (automatic measurement).
The core principle is to impose a specified constant pressure differential across a foam specimen and measure the volumetric air flow required to maintain that pressure.
Key Topics and Requirements
- Test principle: Maintain a constant pressure drop across a standard specimen and measure the air flow value (volume flow rate).
- Specimen and mounting: Standard test cavity dimensions and a specified specimen support (minimum 70% open area). Example chamber geometries in the standard include 140 mm diameter × 150 mm depth or 75 mm diameter × 1000 mm length; specimen cavity 50 × 50 × 25 mm (±0.05 mm).
- Apparatus accuracy: Flow meters with low pressure drop and an accuracy up to ±2%; manometers graduated 0 Pa to 250 Pa with ±2% accuracy. Provision for air supply or vacuum to produce positive or negative pressure.
- Methods:
- A: Suited to conventional flexible foams.
- B1: Manual measurement for low-permeability and sensitive materials.
- B2: Automated measurement for higher repeatability and throughput.
- Reporting and precision: Procedures include conditioning, leak checks, test sequence and reporting items. An annex provides precision data for methods B1/B2.
Applications and Users
EN ISO 7231:2023 is used to:
- Evaluate foam air permeability and compare effects of formulation or process changes on cellular structure.
- Provide quality control criteria in foam production and R&D.
- Characterize materials for end-use suitability (e.g., cushioning, insulation-not sealing applications).
Primary users:
- Foam manufacturers and compounders, R&D teams, and production quality laboratories.
- Independent test laboratories and material certification bodies.
- Product designers and specifiers assessing foam performance related to breathability and air flow.
Related Standards
- ISO 7231:2023 supersedes ISO 7231:2010 (third edition published 2023).
- Adopted as EN ISO 7231:2023 by CEN.
For conformity and implementation, consult national standards bodies and related test standards for cellular polymeric materials and foam characterization.
Keywords: EN ISO 7231:2023, ISO 7231:2023, air flow value, constant pressure-drop, flexible cellular polymeric materials, foam testing, method A, method B1, method B2, air permeability, CEN.
