Rain-activated sprinkler shut-off system
First Claim
1. A sprinkler shut-off system comprising a sensor unit exposed to the atmosphere for sensing the presence of rain water, said sensor unit having a body of porous concrete therein adapted to be wetted by rain water, a pair of electrodes embedded in said concrete body, electrical circuitry including said electrodes for sensing the conductivity of said concrete body, a control for the sprinkler, and means for shutting off the control when said electrical circuitry senses an increase in conductivity of said concrete body as a result of wetting of said body by rain water and for turning said control back on when said electrical circuitry senses a decrease in the conductivity of said concrete body as a result of drying of said concrete body in the absence of rain water.
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Abstract
A moisture detecting system employs a body of porous concrete with electrodes embedded therein. The body of concrete is contained within a housing having an opening in the top thereof to admit rain. The body may also have electrical probes therein connected to the electrodes, which probes can be embedded in the ground to detect moisture therein.
53 Citations
5 Claims
- 1. A sprinkler shut-off system comprising a sensor unit exposed to the atmosphere for sensing the presence of rain water, said sensor unit having a body of porous concrete therein adapted to be wetted by rain water, a pair of electrodes embedded in said concrete body, electrical circuitry including said electrodes for sensing the conductivity of said concrete body, a control for the sprinkler, and means for shutting off the control when said electrical circuitry senses an increase in conductivity of said concrete body as a result of wetting of said body by rain water and for turning said control back on when said electrical circuitry senses a decrease in the conductivity of said concrete body as a result of drying of said concrete body in the absence of rain water.
Specification