A flow cell consists of a cast acrylic tube, which holds the soil or other porous medium, and two removable end-plate assemblies, one mounted on each end of the tube. The tube and the top and bottom end-plate assemblies are held together with 3 rods. Each end-plate assembly has one access port in its center. Additional access ports can be ordered for the-endplate assemblies, as well as for the acrylic tubes. Borosilicate glass, stainless steel, aluminum, polypropylene tubes are also available upon request.

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.