B071 Drain stack air pressure

Characteristics of air transient pressure at drainage stacks of steady discharges: a statistical modelling study

Brief:

The maximum transient air pressure at a discharging drainage stacks is an important design parameter for the drainage system in high-rise buildings. As the pressure fluctuated, measurements of the inside of the drainage stacks at coarse sampling intervals would defeat the data quality; however, ultra fine sampling frequency would not be practically cost justified. This study examines the air pressure variations characteristics in a discharging drainage stack of a full-scale drainage experiment tower at steady flow rates. The pressure was described in terms of the fluctuation frequency, the maximum pressure, and the average pressure with its standard deviation. Correlations between physical parameters were investigated. In particular, mathematical expressions were proposed to correlate the maximum transient air pressure with the probability density function of the measured pressure. Good correlations with the measured results were reported. This study enhanced the understanding of transient air pressure characteristics at a discharging drainage stack and the result would be useful for air pressure measurements at drainage stacks of high-rise buildings.

Further Information:

Wong LT, Mui KW, Cheng CL, Yen CJ, He KC, 2008. Characteristics of air transient pressure at drainage stacks of steady discharges: a statistical modelling study, The 34th CIBW062 International Symposium of Water Supply and Drainage for Buildings, 8-10 September, Hong Kong, China, pp. 376-386.