FloPlast AF32 - Underground Drain Ventilation

7
Figure 4 Installaon
FloPlast AF32 or AFE32 valve
FloPlast AF32 or
AFE32 valve
32mm
40mm
40mm
(a) installaon to prevent self-siphonage
(b) installaon to prevent induced siphonage
Up to ve wash-basins
50mm minimum
6.2 To contribute to the venlaon of the underground drain and to minimise the eects of excessive back pressures
when a drain blockage occurs, the branch or main drain serving a stack or stacks ed with a FloPlast valve may require
a venng point upstream of the stack connecon. Guidance is given in Table 3 and Figure 5.
Table 3 Air admiance valve disposion
Number of
Dwellings Up to three stories in height Mul-storey domesc dwelling and non-domesc buildings
1 – 4 Addional drain and venng not required Convenonal drain venng to be provided if more than one
such building, each equipped with the valves, is connected
to a common drain which is not itself vented by means of a
venlaon stack or discharge stack not ed with a valve.
5 – 10 Convenonal venlaon (open-topped discharge
stack) to be provided at the vent stack at the head
of the installaon.
11 – 20 Convenonal venlaon (open-topped or dis-
charge stack) to be provided at the vent stack at
the head of the installaon and at mid-point of the
system.