NA-05 - Cleaning: Solids in Drain and Sewer Systems (Demo)

Transport behaviour of solids

Transport behaviour of solids (7)

The required minimum wall shear stress for a deposit-free operation depends on the volume concentration of the suspended solids. This amounts to a ATV-A 110 combined and rainwater sewage concentration of cT = 0.005 % [ATVDVWKA 110:2001]:

Equation 8:

with Q in m³/s irrespective of the diameter and slope of the line under consideration.
 

The wall shear stress τvorh is calculated by

Equation 9:

with
ρ = density of the waste water [kg/m3]
g = gravitational acceleration [m/s2]
rhy = hydraulic radius (A/lU) [m]
I = slope [-]
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