ABSTRACT
Seal losses produced by fl ow down the stack depend on the following design considerations-(a) Flow load (depends upon the number of appliances connected to the stack and the frequency with which they are used), (b) diameter of the stack, (c) height of the stack. Excessive seal losses can be prevented by choosing the size of the stack appropriate to the height of the building and to the number of appliances connected to it. Where the layout of appliances is suitable, careful design and installation can lead to considerable economies in pipework, the need for separate vent pipes being eliminated. Where these recommendations cannot be followed, traps should be ventilated by pipes of adequate size.
