A reciprocating diaphragm pump (820, 828) comprising: a flexible diaphragm; a first rigid body having a curved pumping chamber wall; a second rigid body having an opposing curved control chamber wall; wherein the diaphragm is interposed between the pumping chamber wall and the control chamber wall to define a pumping chamber and a control chamber; wherein the control chamber is an air actuation chamber including an entrance hole for air actuating the pump and the pumping chamber comprises a fluid inlet side having an inlet and a fluid outlet side having an outlet for pumping liquid; and wherein the diaphragm comprises: a peripheral bead arranged to locate the diaphragm between the first rigid body and the second rigid body; a diaphragm body having a curved, semi-spheroid or domed shape, the diaphragm body configured to generally conform to a curved inner surface of the pumping chamber wall or a curved inner surface of the control chamber wall, and the diaphragm body having a pumping side facing the inner surface of the pumping chamber wall and an opposing control side facing the inner surface of the control chamber wall; a transition region between the peripheral bead and the diaphragm body, the transition region pinched or clamped between a clamping region of the first rigid body and an opposing clamping region of the second rigid body; wherein the diaphragm is pre-formed or molded so that its relaxed or unstressed state has the control side convex to the control chamber side and the transition region between the bead of the diaphragm and the diaphragm body naturally curves away from the pumping chamber wall as the transition region emerges from contacting the clamping region of the first rigid body and the opposing clamping region of the second rigid body, such that during a delivery stroke, the elastic force of the diaphragm resisting its deployment into the pumping chamber prevents a peripheral portion of the diaphragm body from fully contacting the pumping chamber wall. a flexible diaphragm; a first rigid body having a curved pumping chamber wall; a second rigid body having an opposing curved control chamber wall; wherein the diaphragm is interposed between the pumping chamber wall and the control chamber wall to define a pumping chamber and a control chamber; wherein the control chamber is an air actuation chamber including an entrance hole for air actuating the pump and the pumping chamber comprises a fluid inlet side having an inlet and a fluid outlet side having an outlet for pumping liquid; and wherein the diaphragm comprises: a peripheral bead arranged to locate the diaphragm between the first rigid body and the second rigid body; a diaphragm body having a curved, semi-spheroid or domed shape, the diaphragm body configured to generally conform to a curved inner surface of the pumping chamber wall or a curved inner surface of the control chamber wall, and the diaphragm body having a pumping side facing the inner surface of the pumping chamber wall and an opposing control side facing the inner surface of the control chamber wall; a transition region between the peripheral bead and the diaphragm body, the transition region pinched or clamped between a clamping region of the first rigid body and an opposing clamping region of the second rigid body; wherein the diaphragm is pre-formed or molded so that its relaxed or unstressed state has the control side convex to the control chamber side and the transition region between the bead of the diaphragm and the diaphragm body naturally curves away from the pumping chamber wall as the transition region emerges from contacting the clamping region of the first rigid body and the opposing clamping region of the second rigid body, such that during a delivery stroke, the elastic force of the diaphragm resisting its deployment into the pumping chamber prevents a peripheral portion of the diaphragm body from fully contacting the pumping chamber wall. a peripheral bead arranged to locate the diaphragm between the first rigid body and the second rigid body; a diaphragm body having a curved, semi-spheroid or domed shape, the diaphragm body configured to generally conform to a curved inner surface of the pumping chamber wall or a curved inner surface of the control chamber wall, and the diaphragm body having a pumping side facing the inner surface of the pumping chamber wall and an opposing control side facing the inner surface of the control chamber wall; a transition region between the peripheral bead and the diaphragm body, the transition region pinched or clamped between a clamping region of the first rigid body and an opposing clamping region of the second rigid body; wherein the diaphragm is pre-formed or molded so that its relaxed or unstressed state has the control side convex to the control chamber side and the transition region between the bead of the diaphragm and the diaphragm body naturally curves away from the pumping chamber wall as the transition region emerges from contacting the clamping region of the first rigid body and the opposing clamping region of the second rigid body, such that during a delivery stroke, the elastic force of the diaphragm resisting its deployment into the pumping chamber prevents a peripheral portion of the diaphragm body from fully contacting the pumping chamber wall.