Waste water system

The standard that regulates the dimensioning of gravity waste systems inside buildings is the European Standard UNI EN 12056. The dimensioning process of a waste system can be divided up into the following phrases:

1. Calculation of the flow rates in relation to the drainage units of the sanitary fixtures connected. So we got the flow rate of each sanitary fixture according to the Standard, DU(l/s):

Washbasin = 0.5 l/s

WC (9 litre cistern) = 2.5 l/s

Wall urinal =0.2 l/s

And as our system doesn't have continuous flow rates or waste water pumps, then the total flow rate for each section is equal to the flow rate of the waste waters caused by sanitary fixtures (l/s):

Qtot=Qww=K*sqrt (sum DU), for our school project, the coefficient K is 0.7.

2. Determination of the diameters of branches that connect the sanitary fixtures to the waste stacks.

3. Select the general gradient as 1cm/m, and according to the diagram, select the right size of pipe.

Water flow and pipe size chart