Patent ID: 7614094

Claim:
A system that is hydraulically independent to provide anticipatory, automatic, suction drain entrapment prevention for a user of a swimming pool, spa, or wading pool, the system comprising: (a) a water filled vessel, a water circulation means, at least one underwater suction drains with covers, piping connections, and an active ultrasonic sensor transmitter producing electronic pulses; (b) a transducer assembly to convert said electronic pulses into ultrasonic echo pulses that radiate from within said at least one suction drain, through said at least one covers of said drain, to said water beyond said drain cover; (c) an ultrasonic sensor receiver for detecting ultrasonic echo pulses from said at least one drain covers, a water level or a vessel wall, and user that is in a predetermined proximity to the at least one drain covers; (d) said ultrasonic echo pulses pass through said drain cover to the location of said transducer assembly; (e) said ultrasonic echo pulses is converted to input electronic signal pulses by said ultrasonic sensor receiver and logic circuits in combinations providing a predetermined decision criteria based upon said sequence of echo pulses including those from said drain cover, said water level, or the opposite vessel wall, and said user in a NO-GO range gate, or said user in an OK range gate; (f) a control means for automatically stopping water flow via said water circulation means, based on the presence or absence of each of said at least one echo pulses from the at least one drain covers, said water level or said vessel wall, and said user that is in a predetermined proximity to the at least one drain covers in said sequence of echo pulses; wherein said control means determines if said user is in said predetermined proximity to the at least one suction drain, if said drain cover is not present by automatically self-calibrating to determine if said drain cover echo pulse is within a predetermined range, and if said water level is not within a predetermined range by automatically self-testing to determine if said water level echo pulse is within the predetermined range so as to stop water flow to prevent suction entrapment.