Detergency in soil and vent pipe (SVP) systems

Current soil and vent pipe (SVP) system design guides aim to produce ventilated drainage networks, which protect attached water trap seals from unwanted air pressure effects that cause failure of trap seals. The ventilation design guides are based on steady-state experiments utilizing cold clean water as a test medium. However, most `grey' and `black' water sources are dosed with detergent, and are often warm, which significantly alters the behaviour when compared to the use of clean water. Thus, current design standards provide only approximations of SVP system response. This paper quantifies the effect of detergents in SVP systems in terms of observed air entrainment rates and previously published research on the factors that contribute to air entrainment.