Outlet flow velocity

Hello, I am a spanish student and I was wondering if someone can give me a hand to calculate the diameter of the outlet pipe on the hull to wich arrives different pipes from the systems. The outlet pipe is vertical and I have connected the pipes coming from the Air conditioning refrigeration, generator refrigration, water maker, cocpit, etc.... I can calculate the flow coming from the different pumps but not the outlet velocity through the hull. I guess the pressure acting is going to be the atmosferic as there is no pump. The connection are above waterline.
How can I get the velocity of the flow (assume watre) generated from that pressure? Any relation within this two parameters?
Is the water inside the pipe (until the waterline) going to affect the outlet?

Thank you very much,

Luis

 

Link below could be helpful.

http://www.engineeringtoolbox.com/sewer-pipes-capacity-d_478.html

 

Hi Syed,
Thank you for your quick answer. I would try to take some information from this site. The problem is that the outlet pipe is vertical, i.e a decline of 100 ft for a pipe of 100 ft, I guess. Then the values are for half filled pipes of 100 ft, which takes into account the pressure of 50 ft. The pipe I m designing will have 6 ft. However I l ld do some regression analysis and try to get some values even if they are no very accurate,

Cheers,

Luis.