Insane Hydraulics
Bold and audacious blog about fluid power
This calculator plots the pressure drop graph for a given flow range and orifice diameter. The pressure drop is calculated using the following formula (read about how it is derived here):
$$\Delta P = \frac{8\rho Q^2}{C_d^2 \pi^2 d^4}$$
It is interesting to see that when you set the lower value of the flow rate range to zero - the shape of the curve is constant, and the only things that change are the numeric values at the ends of the coordinate axes. I assure you that there's no corner-cutting here - the line is being re-drawn pixel-by-pixel by the script every time a parameter is changed.
Use the slider below the graph to move the flow rate arrow and see the corresponding pressure drop value. Use the coarse/fine buttons to tweak the parameters, or input the values directly into the fields.