9.100

PRINCIPLES

The main purposes of a drain-ventilating pipe are to prevent undue concentrations of foul air and to provide sufficient ventilation. Ventilation is required to avoid loss of water in a siphon seal caused by siphoning and to prevent admission of foul air to the building caused by back-pressure. Ventilation pipes have to be so installed that water cannot be retained in them. They should be fixed vertically, and whenever possible horizontal runs should be avoided.

9.200

CORROSION RESISTANCE

In principle the same requirements apply as for drainage pipes, however, more attention is required to corrosion resistance. Note: galv. sheet metal pipes are not permissible.

9.300

MINIMAL REQUIREMENT

A building requires at least one ventilation pipe, with a diameter of not less than 100 mm i.d.

9.310

Leader/Stack vent - The upper end of a leader or stack is to be continued (with a pipe having the same diameter as the drainage pipe), to the open air above roof level.

9.320

Branch and connector pipes - Normally sufficient ventilation is provided from the leader, However, where the installation is not within the range of the leader's ventilation, additional vent pipes (e.g. secondary vents) are to be installed to secure sufficient air flow.

9.400

TERMINATION OF VENT PIPES

The ventilation pipe has always to be taken above the level of the flat roof or of the eaves or terrace parapet, whichever is higher, or the top of any window.

9.410

Flat roofs - Vents of leaders are to be fitted separately to a leader and to be of the same diameter as the leader, to a height of 0.3 m above roof level. In regions with heavy snowfalls the vent should be correspondingly higher.

Figure

9.420

End of vent pipes - Caps on vent pipes (vapour pipe) and end pieces with cross-sectional narrowing of diameter should not be fitted, since they may endanger the proper functioning of the drainage system.

9.430

Layout - The vent pipes led to the outside and above the building have to be so arranged that there may be no occurance of odour annoyance. (Facades, windows, terraces, air conditioning plants, ventilations, etc.)

9.500

DISTANCES

Vent pipes having an exit nearer than 2 m to a window of inhabited rooms, have to be led to a minimum of 0.1 m above the lintel.

Figure

In districts with mixed drainage systems, storm drains having inlets without siphons, require to have a distance of 2 m from windows of inhabited rooms.

9.600

VENT LOOPS

Vent pipes require a minimum slope of 1%, for the drainage of the expected condensed water.