Abstract: A magnetically coupled positive displacement pump with a metallic containment can has high and low pressure port passageways through a flange of the pump which provide communication between the interior of the can and the pumping cavity of the pump to remove heat generated by eddy currents in the can. Either or both of the port passageways can be provided with a removable or otherwise adjustable orifice which allows easy modification of cooling fluid flow rate for improved heat removal to more closely meet the needs of a given application. The invention provides an orifice controlled recirculation rate through the can, easy modification to change the recirculation rate and/or adapt the pump to various fluid properties and improved recirculation performance to expand the application base of the associated pump.