A, use The instrument used to determine the permeability of various types type Geotextile. B, principle structure This instrument is measuring a certain pressure, the vertical water flow through certain Area Geotextile samples, resulting in different flow rate values at a different pressure, do a total of five samples was calculated for each sample at the same pressure the average flow rate, depending on the flow rate of this group under different water pressure, you can draw a graph of the pressure and flow rate, as the water flow rate on the graph is tangent 20mm / s when the curve is the permeability the slope of the tangent. C, the main technical indicators 1, the maximum water pressure: 500mmH2O 2, the sample in contact with water Diameter: Φ50mm 3, for sample thickness: ≤10mm 4, Size: 384 * 384 * 668. D, applicable standards Determination of GB / T 15789-2005 Geotextile and related products without load vertical permeability characteristics