The static airflow resistivity (SAR) expresses the frictional retardation to a quasi-static flow (here acoustic wave in air at rest) through the pores, i.e. the pressure drop required to force a unit flow through the material.
The static airflow resistance expresses the frictional retardation to a quasi-static flow (here acoustic wave in air at rest) through the pores. It is related to static airflow resistivity: σL
The static viscous permeability (SVP) is an effective fluid flow surface independent to the saturating fluid. Both properties are related by the dynamic viscosity μ of the fluid: k = μ/σ.
Equipment: Static Airflow Resistance Meter
Standard: ASTM C 522, ISO 9053-91
Method: Electronic system for the measurement of flow resistance 
Properties: σ – static airflow resistivity (Pa.s/m²); k – static permeability (m²); L – sample thickness (m)
Direct method: σ = (Pe x A) / (Q x L)
Comparative method: σ = Rc x (Pe x A) / (Pc x L)
 M.R. Stinson and G.A. Daigle, “Electronic system for the measurement of flow resistance” J. Acoust. Soc. Am. 83, 2422-2422 (1988).