System geometry must promote self-cleansing velocities. This prevents the accumulation of solids and minimizes blockages. The BS EN 12056 Series Structure
BS EN 12056-1:2000 standard, titled "Gravity drainage systems inside buildings - General and performance requirements," bs en 120561 pdf free download top
Sanitary pipework, layout, and calculation (Rules for toilets, sinks, and showers). System geometry must promote self-cleansing velocities
Gravity drainage systems inside buildings. General and performance requirements. Gravity drainage systems inside buildings
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The standard mandates that every sanitary appliance (appliance discharging foul water) must be fitted with a water seal trap. This trap prevents toxic, foul-smelling sewer gases from entering living spaces. Part 1 establishes that system designs must prevent these traps from emptying due to self-siphonage or induced siphonage caused by pressure fluctuations in the stack. 2. Hydraulic Capacity and Sizing
The standard defines critical terms such as discharge unit (DU) , hydraulic capacity (Qmax) , and air flow rate (Qa) , which are fundamental for proper system design. It also addresses safety concerns including fire and smoke spread prevention, water and gas tightness, and system accessibility for inspection and maintenance.