Particles in a conveyor

[d4rk3lf]

So, how does the Split operator work? Do I need two birth events where I should mark the particles to be extracted from the main flow?

No, you don't need 2 birth events
Split will just split (by percentage) of particles that are in event where split operator is. 

For example, I see that you placed split operator in 3th event. So it will split only particles that are in 3th event. 

If you want them to split before, or right at the very beginning (if I understood you correctly, that is what you want), you just need to move that split operator to the first event. 
Right after birth object operator (and perhaps, position icon), right bellow these 2, you can place split operator, and they will be splitted. 
Half (or whatever percent you type) will go to event where split is leading them. 
the rest will stay, and will look at the next operator, and will proceed normally. 

I hope I explained well... English is not my first language.