Sometimes it is difficult to determine the radius from the flow convergence formation arc to the center of the valve or the arc. Fortunately, if you can draw a line from one side of the arc to the other (the Arc Width) and then from the center of the line to the edge of the arc perpendicular to the width, the radius can be calculated (and may be more accurate, although not studied) from the arc width and height. Enter the values above and the radius is automatically calculated.