Abstract: A moisture-responsive valve includes a water-swellable body within a housing adjacent a moisture-permeable wall thereof for controlling the movements of a valve member with respect to a valve seat in response to the moisture passing through the moisture-permeable wall. The valve member is floatingly mounted between a first spring interposed between the valve member and the housing and urging the valve member away from the valve seat, and a second spring interposed between the valve member and the water-swellable body and urging the valve member towards the valve seat.

Abstract: A moisture-responsive valve assembly includes a housing having a moisture-swellable body to swell in volume in response to soil moisture, and a bi-stable snap-action device for controlling the valve in response to the volume of the moisture-swellable body. The valve assembly further includes a damped delay mechanism effective to close the valve after it has been open for a predetermined period of time.