US Patent 7424896 Automatic flow shut-off system

An automatic system which includes a tripper unit for actuating a device (e.g. valve-closing actuator) upon contact with water. Basically, the tripper unit is comprised of a housing having a cartridge therein which, in turn, is wrapped with an adsorbent paper which prevents a plunger from moving downward. When a leak occurs, water will flow into the housing and into contact with the absorbent paper which will quickly disintegrate allowing the plunger to move downward to thereby actuate the valve actuator to close the valve. The tripper unit may be a separate component of the system or both the tripper unit and the valve actuator can be incorporated into a single unit.