homework and exercises - Is this a correct addition to a pipe friction loss calculation?

I've been using this online calculator to work out the difference in pressure and flow between two ends of a pipe:

Pipe Friction Calculation for Fluid Flow in a Pipe

So far most of it makes sense, and I've managed to figure out the worst of it (pipe relative roughness >_<). The main problem is that we don't have the "Average fluid velocity in pipe $\mathrm{V}$", only the Flow at A in $\mathrm{l}/\mathrm{s}$.

Before you mock the next part I should explain that I'm a software developer, which apparently still qualifies me more for this sort of work than my water engineer brother-in-law...

Anyway, to convert from Flow to Velocity, I made up the following:

L: litres per second at A
D: diameter of pipe (m)

V: fluid velocity (in m/s)

$$V = \frac{ 1000L }{ \pi(D/2)^2 }$$

Is this the correct conversion, or have I missed something?

Answer

Volumetric flow $\Phi = A V$. Therefore the right expression would be

$$V = \frac{ L/1000 }{ \pi(D/2)^2 }.$$

To get volumetric flow in SI units $\mathrm{m}^3/\mathrm{s}$ you should DIVIDE $\mathrm{l}/\mathrm{s}$ by 1000.