A Review of Main Factors Leading to Air Pressure Fluctuations in Branch Drainage Pipes inside Buildings

This paper is to discuss the main factors leading to the air pressure fluctuations in appliance branch pipes and measures to control them. It has been established that the main factors characteristics of a good sanitary pipework system are that it must prevent the transmission of foul air into the building, minimize blockages, provide efficient conveyance of discharge from sanitary appliances and minimize the risk of flooding to any part of a building. However, due to the nature and properties of sanitary appliance discharge, the flow being a three-phase flow which is simplified to two-phase for design computations and discharge being probabilistic, air variations in the horizontal appliance pipe result in phenomenon in which the sanitary network fails to perform as designed and installed to prevent or minimize aforementioned circumstances. It has been established that the main factors to be discussed leading to air pressure fluctuations in the appliance branch pipe are water traps, bend structures, pipe diameter, pipe slope and length, angle and connection mode and ventilation conditions. These factors’ associated control measures have also been presented. However, factors pertaining to concentration of appliance discharge have not been discussed. The result of this discussion will enable designers and installers of sanitary pipework to incorporate measures to control air pressure fluctuations in appliance branch pipes inside buildings.

Rescue Hopes Fading Miners remain trapped beneath mud and water

Rescue work continues at a flooded mine in China’s eastern ShandongPr ovince where 172 people weretr apped on August 17, but hopes ofbr in g ing anyone out alive are dim-