The separate ejector pump is basically a centrifuge with the possibility of becoming a self-priming jet pump with deep suction by fitting the ejector in the well onto the end of the suction pipe. Recirculation of water passing through the Venturi attracts water from below and pushes it through the return (suction) pipe creating enough pressure to take it up to the surface. For these deep suction applications two pipes need to be connected: the delivery pipe to the ejector and the return (suction) outlet, in this case the diameter of the well must be at least 4”. If the pump has to go in a 2” well, a special ejector with an airtight lock on the well is necessary. It works with just the return (suction) pipe by exploiting the space remaining between itself and the 2” well as a second recirculation pipe.