Building drainage system pipes with improved performance at low flow

Abstract

Building drainage system pipes with improved performance at low flow are disclosed. The pipes have two or more conjoined portions. At low flow, only the smaller portion contains sewage, and it provides a higher velocity than the state of the art by providing a greater hydraulic radius. The larger portion, on the other hand, is large enough to provide sufficient capacity at peak flow while maintaining sufficient velocity. The bi-diameter pipes may be used to replace or retrofit round circular pipes in order to maximize the velocity at low flow while maintaining capacity at peak flow.

What is claimed is: 
     
         1 . A pipe for use in building drainage systems, the pipe comprising a non-circular cross section comprising an upper portion having a radius of curvature and a lower portion having a radius of curvature less than the radius of curvature of the upper portion. 
     
     
         2 . The pipe of  claim 1 , wherein the upper portion comprises a circular cross section defining a radius r, the lower portion comprises a circular cross section defining a radius b, and the radius r is greater than the radius b. 
     
     
         3 . The pipe of  claim 2 , wherein a ratio of r:b is at least 1.2:1. 
     
     
         4 . The pipe of  claim 3 , wherein the ratio of r:b is from 1.5:1 to 5:1. 
     
     
         5 . The pipe of  claim 3 , wherein the ratio of r:b is from 1.8:1 to 3:1. 
     
     
         6 . The pipe of  claim 2 , wherein the circular cross sections of the upper and lower portions intersect each other to define at least one edge running along a length of the pipe. 
     
     
         7 . The pipe of  claim 2 , wherein each of the upper portion and the lower portion have a central longitudinal axis, and the central longitudinal axes are substantially aligned in a vertical plane. 
     
     
         8 . The pipe of  claim 7 , wherein the circular cross sections of the upper and lower portions intersect each other to define two edges running along a length of the pipe. 
     
     
         9 . The pipe of  claim 8 , wherein the two edges are located at a vertical height above the central longitudinal axis of the lower portion. 
     
     
         10 . The pipe of  claim 8 , wherein the two edges and the central longitudinal axis of the lower portion are located at the same vertical height. 
     
     
         11 . The pipe of  claim 7 , further comprising at least one substantially planar sidewall connecting the upper and lower portions. 
     
     
         12 . The pipe of  claim 7 , further comprising two substantially planar sidewalls connecting the upper and lower portions. 
     
     
         13 . The pipe of  claim 12 , wherein the sidewalls extend tangentially from the circular cross section of the upper portion to the circular cross section of the lower portion. 
     
     
         14 . The pipe of  claim 2 , further comprising an additional portion comprising a circular cross section defining a radius b′ less than the radius r of the upper portion. 
     
     
         15 . The pipe of  claim 14 , wherein the radius b′ of the additional portion the same as the radius b of the lower portion. 
     
     
         16 . The pipe of  claim 14 , wherein the radius W of the additional portion is greater than the radius b of the lower portion. 
     
     
         17 . The pipe of  claim 14 , wherein the additional portion has a central longitudinal axis vertically below a central longitudinal axis of the upper portion. 
     
     
         18 . The pipe of  claim 14 , wherein the additional portion has a central longitudinal axis vertically offset from a central longitudinal axis of the upper portion. 
     
     
         19 . The pipe of  claim 1 , further comprising a fitting on an end of the pipe structured and arranged to receive the non-circular cross section of the pipe. 
     
     
         20 . A building drainage system comprising:
 multiple plumbing fixtures contained in a building; and   at least one drain pipe contained in the building in flow communication with the multiple plumbing fixtures, wherein the at least one drain pipe comprises a non-circular cross section comprising an upper portion having a radius of curvature and a lower portion having a radius of curvature less than the radius of curvature of the upper portion.