Empirical derivation of flow parameters describing the behaviour of a novel artificial test solid for building drainage systems

Abstract

The empirical investigation and development of a new Drainage Research Group drain-line carry test solid (DRG) for use in building drainage, waste and ventilation system research is described. The ‘shelf life’ of the National Bureau of Standards test solid used historically (NBS solid) was short and variability in results was large, making it problematic for use in extended investigative work. Further investigations revealed that the materials used in its construction were porous and osmosis would be a contributing factor to the variability observed, as would biofilm growth, causing changes in the coefficients of kinetic and static friction. This research is timely in view of the changing (i.e. generally reducing) volume and energy of contemporary discharges through water conservation initiatives such as WaterWise. Modern materials and analytical techniques present an opportunity to update the NBS solid and develop a modern alternative for research. The results from laboratory testing of the DRG solid compare favourably to the results from the NBS solid. The current mathematical description of the behaviour of a test solid used in a computer-based simulation model (DRAINET) is expanded and updated to include the new findings, creating the potential for extensive follow-on uptake of these results and use by other researchers and potentially use as a standard.

Practical application : The research described articulates with other work in this field related to water conservation strategies; specifically, the investigation of potential unintended consequences through failure to maintain effective drain line carry and self-cleansing velocities. The results are suitable for use by researchers generally and by mathematical modellers in particular.