Study on non-destructive testing method and air pressure fluctuations of drainage stacks at a high-rise building

• Main Authors: Wan-Ju Liao, 廖婉茹
• Other Authors: Cheng-Li Cheng
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/4dnu56

博士 === 國立臺灣科技大學 === 建築系 === 99 === A drainage system is one of the most essential facilities in building services engineering. Unfortunately relevant technology used today to analyze it was developed decades ago. This research investigated the case of existing building drainage systems in Taiwan, including our previous studies. Firstly, the purpose of this paper is the development of a non-destructive testing method of air pressure fluctuation in a stacked building drainage system using field observation and experimental study of stack fluid mechanisms. A portable testing device is developed to execute field testing in existing drainage systems to determine air pressure fluctuation in the stacks of buildings. Meanwhile, the Fast Fourier Transform Process is adopted in this paper to analyze the power spectrum of air pressure fluctuation in a drainage stack and to verify the previous theoretical study. Validation obtained from case-studies can be used to confirm the practicality of this portable and non-destructive testing method. As a result, the proposed testing method can be applied to the diagnosis of existing building drainage systems and improve the design of a drainage system in an existing housing complex. The study examines air pressure variations along a discharging stack with unsteady discharging flow rates, including the fluctuation frequency, the maximum and average pressures with their respective standard deviations at a drainage stack of an in-use office building. With a modified constant, the maximum air pressure at the drainage stack could be described by the probability density function of the measured data using earlier proposed mathematical expressions for steady discharging flow rates. The average prediction and the maximum under-prediction of the absolute peak pressure were determined with the margin of errors taken within certain confidence levels. Finally, the results would be useful for understanding the air pressure in drainage stacks and help increase the potential of installing a real-time monitoring system in a high-rise drainage stack.