Nor1517– Airflow resistance #1 Nor 1517 Measurement of Specific Airflow Resistance Ole-Herman Bjor Norsonic AS

Nor1517– Airflow resistance #2 Nor 1517 Air flows in Air flows out Airflows resistivity [Pa∙s/m 3 ]

Nor1517– Airflow resistance #3 Nor 1517 Airflows resistivity [Pa∙s/m 2 ] Specific airflows resistance [Pa∙s/m] Airflows resistivity [Pa∙s/m 3 ]

Nor1517– Airflow resistance #4 Nor 1517

Nor1517– Airflow resistance #5 Nor 1517

Nor1517– Airflow resistance #6 Nor 1517 A: area of test specimen; d:thickness of test specimen; p: sound pressure observed by the microphone [Pa]; f: frequency of excitation, nominal value 2 Hz; A p : area of the piston, nominal value; h: peak-to-peak amplitude of the piston movement; V:volume of the vessel; P a : atmospheric air pressure;  : ratio of specific heat C p /C v for air, nominal value 1,4.

Nor1517– Airflow resistance #7 Nor 1517 Air flows in Air flows out

Nor1517– Airflow resistance #8 Nor 1517 Air flows in Air flows out

Nor1517– Airflow resistance #9 Nor 1517

Nor1517– Airflow resistance #10 Nor 1517

Nor1517– Airflow resistance #11 Nor 1517 Heat conduction Adiabatic compression Isoterm compression Correction corresponds to 0,16 dB

Nor1517– Airflow resistance #12 Nor 1517

Nor1517– Airflow resistance #13 Nor 1517 l Mount the calibration disc and start the motor of Nor1517. l Read the displayed level for the 2 Hz filter band and adjust the sensitivity if required. l Offset the calibration by subtracting 46,1 dB l Set Nor140 to display engineering units (EU) l Switch off the motor and replace the calibration disc with the material to be tested. l Read the specific airflow resistance from the display.

Nor1517– Airflow resistance #14 Nor 1517 Direct readout of specific airflow resistance: 269 = 269 Pa∙s/m 90.7k = Pa∙s/m

Nor1517– Airflow resistance #15 Nor 1517 l Measurement according to ISO l Direct reading of specific airflow resistance. l One large measurement range: 4 – 5 decades. l Calibration level included in measurement range.