A downhole valve having a piston 80 actuated by a pressure differential between an annulus pressure at the valve (from 100) and a pressure at the valve outlet 50b and/or in a portion of the flow path closest to the valve outlet. The valve can have an opening for receiving the annular pressure that is isolated from the valve inlet and valve outlet. The downhole valve can be configured such that it does not operate to open and/or close the flow path based on a pressure differential between the valve inlet and outlet. The valve may be used in an assembly with a pump or lift system such as an ESP (figure 23, 20) which can be used to affect the outlet pressure.
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