Fields of application of airflow resistivity meter

The measuring system possesses a wide operational area. Among other things, this includes:

• Quality control during manufacturing process
  • cylindrical and cuboid specimens in the laboratory
  • plates of materials in situ without destruction
• Input parameters for acoustic modeling
  (see overview measuring systems vs. analysis software)
  • Absorber model according to Delany / Bazeley
  • Phenomenological Model for open porous asphalts, for example for rating of texture of road surfaces
  • Biot-Theory
  • numerical software solutions such as Comsol Multiphysics^*
  • calculation of insertion loss of mufflers (see software for acoustic design of mufflers AcoustiCalc^{® Silencer})

• Optimization in research and development
  • of materials with open porosity
  • of structures and components

Specimen holders

Depending on the application, there are different specimen holders available – specially adjusted types can be delivered on demand.

Specimen holder I

• Application: determination of airflow resistance of materials with open porosity in the laboratory
• Specimens:
  • cylindrical specimens with a diameter of 100 mm (required according to former DIN EN 29053), 40 mm, 30 mm as well as fills, fabrics and coverings
  • alternative cuboid specimens with a cross section of 110 mm x 110 mm
• Method:
  • prepared cylindrical or cuboid specimens of variable thickness are mounted and sealed into the specimen holder

Specimen holder II

• Application: nondestructive determination of the airflow resistance of materials with open porosity in situ
• Specimens: material samples with plane surface of at least 240 mm diameter
• Method:
  • pressing of specimen holder onto the specimen with defined force
  • different seals between specimen holder and specimen can be delivered depending on the application

Software

The airflow resistivity meter is supported by the analysis software AcoustiFlow^® .

• determination of airflow resistance as a function of airflow velocity / volume airflow
• computation of linear regression and extrapolation of airflow resistance to airflow velocity of 0,5 mm/s
• averaging of results of various material samples
• simple management and comparability of results
• optional generation of measurement protocols

Compression specimen holder for airflow resistivity meter

As of now, a novel compression specimen holder extends the application range of the airflow resistivity meter, the impedance tube AcoustiTube^® and the transmission tube.

The specimen holder can be nearly continuously adjusted in length and allows the defined compression of cylindrical specimens of soft materials (e. g. glass wool) and fills to measure the airflow resistance, sound absorption coefficient, characteristic absorber values and the transmission loss. Also, thin fabrics as well as multi-layer systems can be installed with control.

Technical Data

Measurement range cylindrical specimen holder, inner diameter 100 mm (Standard)

• Airflow resistance: 1 kPa·s/m³ – 100.000 kPa·s/m³
• Specific airflow resistance: 0,01 kPa·s/m – 750 kPa·s/m
• Airflow resistivity: 0,05 kPa·s/m² – 150.000 kPa·s/m²

Measurement range cylindrical specimen holder, inner diameter 40 mm

• Airflow resistance: 5 kPa·s/m³ – 100.000 kPa·s/m³
• Specific airflow resistance: 0,01 kPa·s/m – 125 kPa·s/m
• Airflow resistivity: 0,05 kPa·s/m² – 25.000 kPa·s/m²

Measurement range cylindrical specimen holder, inner diameter 30 mm

• Airflow resistance: 10 kPa·s/m³ – 100.000 kPa·s/m³
• Specific airflow resistance: 0,01 kPa·s/m – 70 kPa·s/m
• Airflow resistivity: 0,05 kPa·s/m² – 14.000 kPa·s/m²

Measurement range cuboid specimen holder, inner dimensions 110 mm x 110 mm

• Airflow resistance: 1 kPa·s/m³ – 100.000 kPa·s/m³
• Specific airflow resistance: 0,01 kPa·s/m – 1.200 kPa·s/m
• Airflow resistivity: 0,05 kPa·s/m² – 240.000 kPa·s/m²

Requirements

• Personal computer: Windows 8 / 10 / 11, 2x USB-interface
• Primary pressure at measuring system: 2 bar – 5 bar
  (for example optional compressor)
• Power supply: 230 V (AC), 50 Hz
• Ambient air temperature: 5 °C – 60 °C

possible adjustment of measurement range on demand

^{* Comsol Multiphysics is a registered trademark of the COMSOL, Inc.
** SPERoN is a registered trademark of the Müller-BBM Holding AG}