344 Ball Type Regulating Valve, 344

As shown on the graph, the butterfly valve has the most nonlinear flow curve for final 1/3 (30°) of travel leading to an increase of 75% in flow through the valve. The straight 2-way “R” ball curve is not quite as steep, with the flow through the valve increasing by 60% over the last 30° of travel. The “R” ball, however, has the additional disadvantage of not allowing significant flow during the first 1/3 of its rotation. Since a small change of rotation causes a significant change using these valves, trying to regulate large flows when the valve is two thirds to full open presents a challenge.