{HEAD ~ A safety device} for avoiding entrapment at a water reservoir drain by using {TAIL ~ a vacuum operated switch} to interrupt power to the reservoir pump and by using a pressure pump to generate a positive pressure to dislodge the obstruction from the drain should a blockage occur 
{ HEAD ~ A safety device } for avoiding entrapment at a water reservoir drain by using { TAIL ~ a vacuum operated switch } to interrupt power to the reservoir pump and by using a pressure pump to generate a positive pressure to dislodge the obstruction from the drain should a blockage occur
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