Fire Demand and looping a water system!

[ninim2200]

Hi,
i am designing a small system that is connecting to a bigger water system, there are 2 potential points of connections (points A and B), Point A is infront of the site with a known pressure and supply (I used pump and reservoir)Point A connects to a water Tank ( Tank C), the other point (Point B) is going up a hill and connects to the same tank ( Tank C).
So when i connnect to only Point A, i get enough water demand and pressure and all my system pass the Fire flow requirements, when i try to loop the system the demand goes way down since point B goes through a high elevation almost the same elevation as the base of the Tank, Does it make sense that connecting to point B will affect the demand on my site even though i am connecting to point A which by iteself has enough pressure and demand!
Thanks for your input.

 

[coloeng]

How and where you connect the system should have no effect on the demand. The demand is based on usage and fire flow. By having two connections you should decrease the flow from each of the connection points which decreases the velocity in the pipes and reduces headloss. You should see an increase in pressure for the small system if you have it connected at both points A and B. Even though the water line that connects at point B is going up a hill that has an equivalent elevation as the base of Tank C, so long as the tank has a water level above the base and the hydraulic gradelin in the pipe from the connection at B doesn't drop below the elevation in the pipe line, you should get adequate flow through the the connection at B.

Again, demand is independent of how and where you connect.