Improving the Minimum Design Velocity of Sewage Pipes

Abstract

The minimum design velocity for sewage pipes is set based on the planned quantity; however, deriving a reasonable design with only a single standard is limited. Thus, it is necessary to review whether consistent standards, such as the current minimum flow velocity, can efficiently transport the particles flowing in pipes. Improving the design that can determine the minimum design velocity rate and slope according to the concentration, specific gravity, particle size, and characteristics of the pipe material of the sediment flowing into the sewer system is necessary. In this study, the minimum design velocity for each particle size was examined based on the results of the simulation of fluid-solid multiphase flow required for the review process of hydraulic properties inside the pipe. The minimum design velocity standards for domestic and international sewage systems were investigated and compared, and a minimum design flow rate prediction equation was proposed considering the sedimentation. The equation includes the relationship between the particle size and pipe diameter and can be easily estimated.