Abstract: The invention generally provides a dynamic back pressure regulator. In exemplary embodiments, the back pressure regulator includes an inlet, an outlet, a seat disposed between the inlet and the outlet and defining at least part of a fluid pathway, and a needle displaceable relative to the seat to form a restriction region therebetween for restricting fluid flow between the inlet and the outlet. In some embodiments, the needle can be formed of a chemically resistant ceramic or have a metal plating to provide corrosion and/or erosion resistance.