Hydraulic Conditions in Foul Water Stacks

Foul water stacks are a separate chapter in the design of sanitary installations, especially in high-rise buildings. The problematic part is the complicated hydraulic conditions in the stacks, which lead to high values of negative pressure and overpressure. Exceeding the maximum negative pressure values leads to the extraction of water from the traps, which causes the spread of annoying smells in the interior. Another problematic part is the high hydraulic jumps caused by a sudden change in the velocity of water in the stack, especially above the change in the direction of stacks. Such sudden changes in velocity cause excessive vibrations and noise that spread from stacks to the building structures and surrounding areas. The contribution deals with the issue of hydraulic conditions in the flow of foul water in stacks, assessment of the maximum values of negative pressure and overpressure, technical solutions that ensure optimal water flow in the drainage systems of buildings. Based on measurements that were performed in companies abroad, the authors prepared graphs of pressure fluctuations in stacks for selected boundary conditions.