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.
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