The design and installation of drainage systems range from simple to complex, depending on the type of building, the local code and the occupancy requirements. The local plumbing code will include requirements for acceptable materials, installation and inspection, and these must be followed as the first requirement of an acceptable job.
There are usually differences-sometimes minor, sometimes quite important-among plumbing codes. Among the features which differ from code to code may be minimum tube sizes, permissible connected fixture loads, fittings and connections, methods of venting, supports and testing. Few codes are completely specific about installation details and leave the responsibility of proper and suitable installation to the designer and the contractor.
In large and multistory buildings, the design will generally require the services of a mechanical engineer and a plumbing designer. The plumbing designer has the responsibility for coordinating the drainage system design within the overall building construction requirements. A good drainage design must accommodate the problems of installation space, building movement, support, expansion and contraction, pipe sleeves, offsets and provisions for necessary maintenance.
In residential buildings and small one- and two-story commercial buildings, the drainage piping is usually straightforward in design and simple in installation. Type DWV copper tube, installed with good workmanship by an experienced plumber, will provide many years of trouble-free service.
The smaller diameter of DWV tube and fittings makes it possible to install copper drainage systems where other competing piping materials would be impossible, difficult or more costly. For example, a 3-inch copper stack has only a 3-3/8-inch outside diameter at the fitting and can be installed in a 3-1/2 inch cavity wall.
Prefabrication
Considerable savings can be effected by prefabricating copper DWV subassemblies. Prefabrication permits work even when adverse weather prohibits activity on the job site. Simple, inexpensive jigs can be made to position the tube and fittings during assembly and help eliminate costly dimensional errors. Freedom of movement at the bench permits joints to be made more readily than at the point of installation, where working space may be limited.
Soldered joints are strong and rigid. Subassemblies can be handled without fear of damage. The lightweight features of copper DWV tube and fittings make it possible to handle fairly large assemblies. Other dependable drainage plumbing materials may weigh three to four times as much. Subassemblies require a minimum of support when connected to a previously installed section of a drainage system.
Copper DWV tube has been used successfully for years in all parts of drainage plumbing systems for high-rise buildings-for soil and vent stacks and for soil, waste and vent branches. Copper tube's light weight and the ease with which it can be prefabricated have been especially important in high-rise drainage systems.
Additional details on copper applications in drain, waste and vent area can be found in the Copper Tube Handbook.