Updated: Oct 30, 2020
The area and velocity of flow through the pipe are inversely related through the Conservation of Mass Principle. For an incompressible fluid A1V1 = A2V2, where A is the area through which liquid is flowing and V is the velocity of the liquid.
As the ball valve rotates and the area of flow is decreased, the velocity of the fluid increases, and therefore the fluid travels a greater distance once released from the valve.
When fed water from a faucet at 66 psi, the pressure in the ball valve remained constant at 66 psi although both the area of fluid flow and velocity of the fluid were fluctuating inversely. More sensitive gauges would reflect a drop in pressure as the cross-sectional area of flow decreases.
Fully open ball valve, maximum water projection is 3.5".
Fully closed ball valve, no water projection.
With partially opened ball valve, maximum water projection is 17' 7" and wets concrete wall 17' 7" distant.