Flow resistance measuring system

m|ars – Measuring system for determining the specific airflow resistance

Measuring the airflow resistance with m|ars ensures a convenient assessment of the sound absorption capacity of different types of materials. Small sample sizes and the short measurement duration of only a few minutes are ideal for its use in routine production monitoring. Moreover, when developing new materials, m|ars helps to shorten and simplify the preselection process.

The measuring principle

m|ars uses the direct airflow method as described in standard EN 29053 for measuring the airflow resistance. To this end, a constant volume airflow is passed through the sample. The overpressure building up in front of the sample is measured. The ratio of overpressure to flow velocity results in the airflow resistance, which for most porous materials is not related to the airflow velocity. According to EN 29053, the airflow resistance extrapolated to an airflow velocity of 0.5 mm/s is referred to as the specific airflow resistance.

The measuring setup

For measuring different samples, m|ars is equipped with a pressure cylinder: Thin samples such as fabrics or felts are clamped to a flange; thick, flexible samples can be pressed to a predefined thickness. A set of tubes of varying lengths makes it possible to measure firm samples.

Technical specifications

  • Volume flow is adjustable from 0.1 Nl/min and 6 Nl/min
  • Differential pressure measurable between 0.1 Pa and 10 Pa
  • Measurable flow resistance between 10 Pa s/m and 40,000 Pa s/m

System requirements

  • Dry compressed air that is oil-free and particle-free (1 bar – 15 bar)
  • PC with Windows XP or higher and a USB port

The order includes

  • Pressure cylinder with various fixtures for measuring thin, pressed or thick samples
  • Measuring unit with air pressure reducer, volume flow regulator, differential pressure gauge and air pressure sensor
  • Sensor for measuring temperature and humidity in the pressure cylinder
  • Stencil for cutting holes in thin samples using a hollow punch so they can be clamped on the flange of the pressure cylinder
  • 2 reference resistors
  • Software and documentation (pdf file)

Additional pages