Hydrodynamic calculation Needle valve
Values for calculation
Calculation
Velocity in valve
$$v_{max}=\cfrac{4\cdot 10^6\cdot Q_{max}}{π\cdot D^2}$$Theoretical pressure in the valve at full opening
$$Δ_h=\cfrac{v_{max}^2}{2\cdot g}\cdot \left(ζ+1\right)$$Pressure parameter
$$p=\cfrac{Δ_h}{H}$$$$0 < p \le 1$$Effective closing time factor
$$c_{ef}=0$$Under-pressure behind the valve
$$P_{u}=\max\left(-\cfrac{L\cdot v_{max}}{g\cdot t\cdot c_{ef}}, -10\right)$$