Appareil de mesure de la conductivité hydraulique

The ku-pF apparatus is a laboratory instrument for the automatic determination of any saturated hydraulic conductivity ku and the pf curve (water tension curve) in accordance with the condensation method on up to 10 soil ring samples simultaneously.

The apparatus is designed for the use of the UGT soil sample rings with 250 cm³ inner volume and 41 cm² cross sectional area. These soil sample rings have bore holes arranged exactly at height intervals of 3 cm for the insertion of the tensiometers. However, they may also be used for obtaining samples separately from the ku-pf apparatus.

The filled soil sample rings are set onto filter plates, saturated and sealed basally in the carrier basket for the test run. The gradient resulting from the condensation on the free ground surface is recorded by two tensiometers which record the corresponding water content and the flow rate by periodical weighing respectively.

The Tensio 130 tensiometers with particularly small ceramic cup (Ø = 6,5 mm / L = 20 mm) provide exact measurements with a minimum destruction of the soil. Air bubbles are easy to recognise and eliminate through the acrylic head with bleed screw.

The arrangement of the samples on the star shaped carrier which rotates at the set test interval permits the examination of 10 samples simultaneously. The sample on the weighing position is lifted from the carrier by lifting the scales so that it is standing free. The weighing data and the tensions here are stored on the internal data logger. Automatic
measuring produces continuous measurement series with a minimum of monitoring. The scales are automatically balanced between weighings. Drift effects or any foreign bodies on the scales do not therefore cause any interference. The ku-pf apparatus works independently of a PC due to the integrated data logger and a microcomputer. A connection
must be created to the PC only for maintenance, test start and reading out of the data.