By using SMS flow cells, hydraulic properties (the saturated hydraulic conductivity, the unsaturated hydraulic conductivity, and soil water retention) can be determined on the same soil core. Column tensiometers are recommended for determining the unsaturated hydraulic conductivity. Small column tensiometers, with or without pressure transducers, are available from SMS.
Each end-plate assembly consists of two parts: a round doughnut shaped part containing an o-ring slides over the end of the column, and a flat round plate which holds a perforated aluminum support disc. There is a gasket between the two plates, as well as a porous nylon membrane (bubbling pressure 30 mbar) or a membrane filter (bubbling pressure 600 mbar). When needed, the membranes can easily be replaced. Flow cells come in nine standard tube diameters: 1.5, 2.0, 2.25, 2.5, 3.0, 3.25, 3.5, 4.0, and 5.25 inches outside diameter. The inside diameters are 0.5 inches less than the outside diameters. Flow cells can be made in nearly every length.