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Enabling better global research outcomes in soil, plant & environmental monitoring.

Extractor 15 BAR Membrane

The Model 1000 Pressure Membrane Extractor incoporates disposable cellulose membranes in the extraction of water from soil samples over a pressure range of 0 to 15 bars. A compression diaphragm in the lid holds the samples in firm contact with the membrane, ensuring proper hydraulic contact needed for the extraction process.

The Pressure Membrane Extractor includes the following components: top and bottom plates, 5/8 inch (1.6 cm) high by 11 inch (28 cm) inside diameter cylinder and clamping bolts, cylinder seal O-rings, screen drain plate, compressing diaphragm, and eccentric clamping screw assembly. Connecting hoses (2 required), cut cellulose membrane discs, PM Hinge, and torque wrench with socket are ordered separately. Soil sample retaining rings and cylinders of various heights are available separately.

Weight: 72.00 Lbs (32.66 kgs)

When air pressure inside the Pressure Membrane Extractor is raised above atmospheric pressure, the higher pressure inside the Extractor chamber forces excess water through the microscopic pores of the Cellulose Membrane and out of the Extractor. The high pressure air will not flow through the pores of the Cellulose Membrane since they are filled with water. The surface tension of the water in the pores at the air-water interface supports the pressure, much the same as a flexible rubber diaphragm. When the air pressure inside the Extractor is increased, the radius of curvature of this interface decreases. Water films will not break and allow air to pass through, even at maximum extractor pressure because of the minute pore diameter (24 angstroms). There is an exact relationship between the amount of air pressure in the Extractor and the radius of curvature of the air-water interface of the water in the pores of the Cellulose Membrane.

When soil samples are placed on the Cellulose Membrane in the Extractor and saturated with water and the air pressure in the Extractor is raised above atmospheric pressure, water will flow from around each of the soil particles and out through the pores of the Cellulose Membrane. At any given air pressure inside the Extractor, water will flow until the curvature of the water films at the junction of each of the soil particles is the same as in the pores of the Cellulose Membrane and corresponds to the curvature associated with that pressure.

Pressure Extractors References
Azooz, R.H. and Arshad, M.A. 1995, ‘Tillage Effects on Thermal Conductivity of Two Soils in Northern British Columbia’, Soil Science Society of America Journal, vol. 59, pp. 1413-1423.

Azooz, R.H., Arshad, M.A. and Franzluebbers, A.J. 1996, ‘Pore Size Distribution and Hydraulic Conductivity Affected by Tillage in Northwestern Canada’, Soil Science Society of America Journal, vol. 60, no. 4, pp. 1197-1201.

Cresswell, H.P., Green, T.W. and McKenzie, N.J. 2008, ‘The Adequacy of Pressure Plate Apparatus for Determining Soil Water Retention’, Soil Science Society of America Journal, vol. 72, no. 1, pp. 41-49.

Duniway, M.C., Herricka, J.E. and Monger, H.C. 2007, ‘The High Water-Holding Capacity of Petrocalcic Horizons’, Soil Science Society of America Journal, vol. 71, pp. 812-819.

Fuentes, J.P., Flury, M. and Bezdicek, D.F. 2004, ‘Hydraulic Properties in a Silt Loam Soil under Natural Prairie, Conventional Till, and No-Till’, Soil Science Society of America Journal, vol. 68, pp. 1679–1688.

Giakoumakis, S.G. and Tsakiris, G.P. 1999, ‘Quick Estimation of Hydraulic Conductivity in Unsaturated Sandy Loam Soil’, Irrigation and Drainage Systems, vol. 13, pp. 349-359.

Katsura, S., Kosugi, K., Yamamoto, N. and Mizuyama, T. 2005, ‘Saturated and Unsaturated Hydraulic Conductivities and Water Retention Characteristics of Weathered Granitic Bedrock’, Vadose Zone Journal, vol. 5, pp. 35-47.

Luedeling, E., Nagieb, M., Wichern, F., Brandt, M., Deurer, M. and Buerkert, A. 2005, ‘Drainage, Salt Leaching and Physico-chemical Properties of Irrigated Man-made Terrace Soils in a Mountain Oasis of Northern Oman’, Geoderma, vol. 125, pp. 273-285.

Mecke, M., Westman, C.J. and Ilvesniemi, H. 2002, ‘Water Retention Capacity in Coarse Podzol Profiles Predicted from Measured Soil Properties’, Soil Science Society of America Journal, vol. 66, no. 1, pp. 1-11.

Roels, S., Sermijn, J. and Carmeliet, J. 2002, Modelling Unsaturated Moisture Transport in Autoclaved Aerated Concrete: a Microstructural Approach, Building Physics 2002: 6th Nordic Symposium, Trondheim, Norway. 17-19 June pp. 167-174.

Young, M.H., Albright, W., Pohlmann, K.F., Pohll, G., Zachritz, W.H., Zitzer, S., Shafer, D.S., Nester, I. and Oyelowo, L. 2006, ‘Incorporating Parametric Uncertainty in the Design of Alternative Landfill Covers in Arid Regions’, Vadose Zone Journal, vol. 5, pp. 742-750.