Abstract: A motor with associated load sensor is connected to a circulation pump of a swimming pool circulation system. The load sensor performs the function of a safety vacuum release system by detecting underload of the motor. Underload is now discovered to be reliably indicative of blockage on the intake side of a circulation pump. A switch controlled by the load sensor shuts off the motor in response to a suitable underload. Vacuum on the intake side of the circulation pump neutralizes, thereby freeing a person or object blocking the suction line.

Abstract: A flow blockage suction interrupt of the present invention reduces the dangerous possibility of bodily suction entrapment of a bather in a swimming, wading, or hydrotherapy pool. The safety valve operates to instantaneously introduce atmosphere into a suction piping system of a pool when a dangerous vacuum condition is detected. The incoming atmosphere breaks the vacuum, freeing entrapped bather. The safety valve includes a dynamic plug and dual spring-loaded actuators, one closing and one opening the valve to atmosphere. The closing actuator is dominant until the opening actuator is triggered by the dangerously high vacuum level that accompanies bodily suction entrapment. The preferred embodiment incorporates a spring-loaded telescopic actuator shaft that is spring-loaded to open fully once triggered, and is triggered by a factory-calibrated diaphragm-actuated suction sensor. Once this safety valve has been tripped, it must be manually reset by the pool operator.