Abstract: A sensor is provided for testing a composite medium. The sensor includes a tube and three or more conductors which are wound in a continuously parallel helix around the tube such that the conductors are interleaved. The tube is non-porous and electrically insulative. Both the proximal end and the distal end of the tube are open. Each turn of each conductor is equally spaced from the adjoining turns of the other conductors, and the conductors have a common helical length. The sensor can also include a first cap which seals the proximal end of the tube and a second cap which seals the distal end of the tube such that the interior of the tube is always filled with air.

Abstract: A sensor is provided for testing a porous medium. The sensor includes a plurality of porous elements, a number of electrically conductive interface plates which is one greater than the quantity of elements, and the same number of conductors. Each element operates as a discrete variable capacitor, exhibits a different known liquid release curve, and includes a first axial opening. The elements are stacked one on top of another. Each plate includes a second axial opening. The plates are axially distributed within the sensor such that the first and second axial openings combine to form a longitudinal cavity that extends from the sensor's proximal end to its distal end, and each element is sandwiched between a different pair of plates. A distal end of each conductor is attached to a different one of the plates, and a proximal end is routed through the cavity to the sensor's proximal end.

Abstract: The present invention is embodied in a tensiometer apparatus and process that employs novel techniques for performing the required routine service operation of refilling a sealable measurement chamber of the apparatus with liquid from a reservoir using a novel, piston-type, “jet-action” plunger mechanism. These novel techniques result in a tensiometer which is easier to use, requires no tools for assembly or replacement of parts, and is easier and lower cost to manufacture and maintain. These novel techniques also result in a tensiometer which has improved measurement sensitivity and accuracy, higher reliability and a longer operating lifetime than conventional tensiometers.

Abstract: A portable tensiometer for measuring the moisture content of soil, including an elongated housing tube having a hollow porous tip mounted thereon for insertion in the soil, and a hollow handle element having a vacuum gauge secured to one end and a cylinder defining a chamber of adjustable volume at the other end. Capillary tubing, which connects the interior of the porous tip to the adjustable-volume chamber and to the vacuum gauge to form a sealed, normally water-filled system, and the use of a minimal volume of water in the instrument minimizes errors due to changes in temperature to which the instrument is subjected.