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Point Counterpoint: single-stack systems for high-rise buildings: why select the Sovent single stack.

Article Excerpt
Created in 1957, the single stack Sovent system works by utilizing two unique fittings: aerators and deaerators (see drawing on page 24). All other pipe and fittings and connections to these fittings are standard and consistent with conventional DWV systems. The Sovent system is vented through the roof and is open to the atmosphere. There are fixture unit values and sizing requirements along with rules to adhere to. The criteria can be found at www.sovent.com.

Basic Design & Operation. The Sovent system allows the drain, waste and venting to be accomplished through a single stack. The aerator fittings, which are located in the vertical stack, have three outlets to serve various fixture branch connections. The aerator also has a double inline offset configuration, which performs as a vertical velocity break and controls the vertical flow of the waste and water that is discharged into the Sovent system.

Aerator fittings are required within 20-foot intervals so that there is a sufficient column of air within the vertical pipe. At approximately 33 feet, terminal velocity is reached and the falling waste and water can create a "plug" formation, which would cause both a positive and...