Question about ventilation pipe slope

[Fusion916]

Hi all,

From what I understand, each horizontal section of ventilation pipe needs to be positive slopped at 1/4" per foot, is that correct? Such as this:

Also,

Is there a particular slope that is required for vertical sections of vent pipe?

 

[Caduceus]

No slope needed on vertical pipes. They are to be straight up and down (plumb).