ASTM D4491 Water Permeability Testing Machine of Geotextiles by Permittivity 

ASTM D4491/D4491M-22 : Standard Test Methods for Water Permeability of Geotextiles by Permittivity

Water Flow through a Geotextile: Measuring Perpendicular Water Flow and Permittivity

This test standard specification discusses the methods for measuring water flow through geotextiles in the laboratory. This is an important characteristic, as it may be a crucial factor in determining the suitability of geotextiles for filtration, such as water flow into drainage layers. The main testing methods are 'vertical water flow' and 'permeability', which are similar but not identical. Broader information regarding the behavior of filter geotextiles is included in the technical specification titled 'Geotextile Filtration'. The vertical water flow measurement method, which measures vertical water flow (i.e., water flow perpendicular to the plane), is defined by EN ISO 11058, which is almost identical to ASTM D4491. 

The difference is that vertical water flow is defined as the flow rate (in liters per second) divided by the area of the geotextile being tested, but not divided by the head of water. EN ISO 11058 also uses a water head of 50mm for testing, and the results are expressed in velocity.

Permittivity

Permittivity is measured in accordance with ASTM D4491 and is a method most commonly used in the United States. Permittivity is defined as the flow rate (in cubic metres per second), divided by the area of the geotextile tested, divided by the hydraulic head. ASTM D4491 specifies a hydraulic head of 50mm for testing.

Beijing United Test Co.,Ltd. export@unitedtest.com offer the ASTM D4491 Water Permeability Testing Machine of Geotextiles by Permittivity. Contact us now : export@unitedtest.com, unitedtest@hotmail.com