The apparatus further comprises an electrical circuit that automatically shuts off power to the liquid reservoir pump whenever the drain becomes obstructed, while energizing the pressure pump and opening the valve to permit {HEAD ~ the generation} of {TAIL ~ positive pressure} into the drain to dislodge the obstruction 
The apparatus further comprises an electrical circuit that automatically shuts off power to the liquid reservoir pump whenever the drain becomes obstructed , while energizing the pressure pump and opening the valve to permit { HEAD ~ the generation } of { TAIL ~ positive pressure } into the drain to dislodge the obstruction
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