Test Description:
The water flow test provides information concerning a material’s resistance to a fluid flow. Characterization of flow resistance can take place at one specified flow rate, or alternatively, flow resistance can be specified over a range of flow rates (as shown). Typically flow resistance is referenced in terms of differential pressure -- the difference in pressure across the porous material -- at a specified fluid flow rate. As flow rates increase or as flow resistance increases in the porous material, differential pressure increases. Similarly, as pore size and pore volume decrease, or as material thickness increases, flow resistance will increase as well.
The fluid flow curve shown here represents the response of an initially dry porous sample. The challenging fluid is water. In this case, fluid flow rates and backpressures are dependent upon the porous media’s volume that experiences fluid flow. Fluid flow does not occur through a pore until wetted by the fluid, or until the capillary force equation has been satisfied. Until that occurs, the porous material’s active or “flowable” surface area may only be defined as a percentage of the overall surface area and pore volume.
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Applications
Wicking
by Product
