Overview
ISO 9053-1:2018 - "Acoustics - Determination of airflow resistance - Part 1: Static airflow method" specifies a laboratory method to measure the static airflow resistance of porous materials used in acoustical applications. The method measures the pressure drop across a material under controlled, unidirectional (laminar) airflow to derive quantities such as airflow resistance, specific airflow resistance, airflow resistivity and permeability. This standard is used to characterize sound-absorbing foams, fibrous media, textiles and other porous acoustic materials.
Key topics and technical requirements
- Principle: Measure differential pressure across a specimen while imposing a controlled volumetric airflow; calculate resistance as Δp / qv.
- Required equipment:
- Measurement cell (cylindrical or rectangular) sized to the specimen.
- Stable airflow source with fine flow control.
- Volumetric flow meter and differential pressure instrument.
- Thickness gauge for specimen in-situ.
- Performance & calibration:
- Measurement instruments should be calibrated (conventional methods) at least every 2 years.
- Volumetric flow and differential pressure measurements require approximately ±5% accuracy.
- Differential pressure instrumentation must measure down to low pressures (standard specifies capability for very small pressure differences).
- A calibration test specimen shall be measured daily and after significant environmental or hardware changes; measured calibration values must agree with theoretical values within ±10%.
- Measurement cell & specimen geometry:
- Minimum measurement cell diameter specified; lateral specimen dimensions must include a sufficient number of pores/fibres/grains (or a minimum diameter/edge when microstructure is unknown).
- Test support must have minimum open area (≥50%) and hole sizes (≥3 mm); support airflow resistance should be negligible (
