15
5.7 Discharge
Discharge pipes must be metal or suitably temper-
ature rated as defined by G3 building Regulations.
The pipe should have a continuous fall and should
terminate in a safe and visible place.
Downward discharges at low level, i.e. up to 100
mm above external surfaces such as car parks, hard
standings, grassed areas etc. are acceptable pro-
viding that where children may play or otherwise
come into contact with discharges, a wire cage
or similar guard is positioned to prevent contact,
whilst maintaining visibility. Discharge at high level,
i.e. into a metal hopper and metal down pipe with
Valve Outlet size
Minimum size
of discharge
pipe D1
Minimum size of
discharge pipe D2
from tundish
Maximum resistance allowed
expressed as a length of straight
pipe (i.e. no elbown or bends)
Resistance created by each
elbow or bend
G 1/2
15 mm
22 mm
28 mm
35 mm
up to 9 m
up to 18 m
up to 27 m
0.8 m
1.0 m
1.4 m
G 3/4
22 mm
28 mm
35 mm
42 mm
up to 9 m
up to 18 m
up to 27 m
1.0 m
1.4 m
1.7 m
G 1
28 mm
35 mm
42 mm
54 mm
up to 9 m
up to 18 m
up to 27 m
1.4 m
1.7 m
2.3 m
the end of the discharge pipe clearly visible (tundish
visible or not) or onto a roof capable of withstand-
ing high temperature discharges of water and 3 m
from any plastics guttering system that would col-
lect such discharges (tundish visible).
Where a single common discharge pipe serves
more than one system, it should be at least one
pipe size larger than the largest individual dis-
charge pipe (D2) to be connected.
For further information contact your Building
Control Office.
S afety dev ice
(e.g. temperature
relief v alv e)
M etal discharge pipe (D 1) from
temperature relief v alv e to tundish
6 0 0 mm.
maximum
Tundish
30 0 mm.
minimum
D ischarge pipe (D 2) from tundish,
with continous fall. S ee table and
worked example.
D ischarge below
fixed grating
(see text for alternativ e
points of discharge)
Fixed grating
Trapped gulley
Summary of Contents for 1327051
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