Moisture measuring apparatus
AssigneeRaychem Corporation
InventorsGary R. Weihe, Roger D. Lion
Life of this patent
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Abstract
An apparatus for measuring the moisture content of soil includes a chamber having a water-swellable material in the chamber, the chamber being sized so that the water-swellable material can swell to its fully swollen state, with the external resistance, if any, against the swelling being substantially constant. The device includes a device for transmitting water to the water-swellable material so that it is in equilibrium with the environment. A sensor responsive to the volume of the water-swellable material is provided to indicate the water content of the environment exterior of the apparatus. The preferred sensor is a magnet moveable by the water-swellable material and a Hall effect sensing device.
Claims7
An apparatus for measuring humidity comprising:
- (a) a rigid, porous, cylindrical substrate, the substrate being capable of passing water therethrough;
- (b) a tube of water-swellable polymer in contact with the cylindrical substrate, the water-swellable polymer having a fully swollen volume when in its fully swollen state in equilibrium with water at least about 2 times its dry volume, said tube and substrate being substantially completely contained in a chamber, the volume of the chamber being sufficiently large to accomodate the tube in its fully swollen state;
- and
- (c) sensing means responsive to the volume of the water-swellable polymer for producing a signal that varies with the water content of the environment exterior to the chamber.
Dependencies are inferred from the claim text.