This method is used to determine the Filtration Opening Size (FOS) of woven, knitted and non-woven geotextiles but it is particularly recommended for non-woven geotextiles.

This method can be used to measure the FOS of all types and thicknesses of geotextiles with pore dimensions ranging from 40 to 800 m.

The testing and evaluation of a product against this method may require the use of materials and/or equipment that could be hazardous. This document does not purport to address all the safety aspects associated with its use. Anyone using this method has the responsibility to consult the appropriate authorities and to establish appropriate health and safety practices in conjunction with any existing applicable regulatory requirements prior to its use.