Values of certain runner proportions and factors are shown in Fig. 16.16.
All quantities which may vary with either load or speed are here shown as the values for the point of maximum efficiency.
The exact form of a runner profile and the values of these factors will vary from one manufacturer to the next and are developed as a result of experience.
However, the values shown are representative and do show the trend of each as a function of specific speed.
The theory as presented in this chapter represents the capacity of a runner as a function of D, but the quantity which determines capacity is the discharge area of the runner.
This area is determined on the drafting board and is carefully checked in manufacture.