32
300mm
minimum
750mm maximum
Metal discharge pipe (D1) from
temperature relief valve to tundish
Safety device
(e.g. temperature
relief valve)
Discharge pipe (D2) from tundish, with
continuous fall. See 3.55, Table 3 and worked
example
Tundish
Discharge below
fixed grating
(3.60 gives
alternative points
of discharge)
Trapped gulley
Fixed grating
See para 3.33 to 3.39 and 3.50
Diagram 1 Typical discharge pipe arrangement
e
z
i
s
t
e
lt
u
o
e
v
l
a
V
e
g
r
a
h
c
s
i
d
f
o
e
z
i
s
m
u
m
i
n
i
M
(
h
s
i
d
n
u
T
o
t
1
D1
D1
D1
D1
D *
)
e
p
i
p
e
g
r
a
h
c
s
i
d
f
o
e
z
i
s
m
u
m
i
n
i
M
(
h
s
i
d
n
u
T
m
o
rf
2
D2
D2
D2
D2
D *
)
d
e
w
o
ll
a
e
c
n
a
t
s
i
s
e
r
m
u
m
i
x
a
M
t
h
g
i
a
rt
s
f
o
h
t
g
n
e
l
a
s
a
d
e
s
s
e
r
p
x
e
s
d
n
e
b
r
o
s
w
o
b
l
e
o
n
.
e
.i
,
e
p
i
p
h
c
a
e
y
b
d
e
t
a
e
r
c
e
c
n
a
t
s
i
s
e
R
d
n
e
b
r
o
w
o
b
l
e
½
G
m
m
5
1
m
m
2
2
m
m
8
2
m
m
5
3
m
9
o
t
p
u
m
8
1
o
t
p
u
m
7
2
o
t
p
u
m
8
.
0
m
0
.
1
m
4
.
1
¾
G
m
m
2
2
m
m
8
2
m
m
5
3
m
m
2
4
m
9
o
t
p
u
m
8
1
o
t
p
u
m
7
2
o
t
p
u
m
0
.
1
m
4
.
1
m
7
.
1
1
G
m
m
8
2
m
m
5
3
m
m
2
4
m
m
4
5
m
9
o
t
p
u
m
8
1
o
t
p
u
m
7
2
o
t
p
u
m
4
.
1
m
7
.
1
m
3
.
2
Table 1 Sizing of copper discharge pipe ‘D2’ for common temperature relief valve outlet sizes
*See 3.49 and 3.56 and Diagram 1
Note: The above table is based on copper tube. Plastic pipes may be of different bore and resistance.
Sizes and maximum lengths of plastic should be calculated using data prepared for the type of pipe being used.
length should be at least two sizes larger than the
nominal outlet size of the safety device; between 18
and 27m at least 3 sizes larger, and so on; bends must
be taken into account in calculating the flow resistance.
See Diagram 1, Table 1 and the worked example.
Note: An alternative approach for sizing discharge pipes
would be to follow Annex D, section D.2 of BS 6700:2006
Specification for design, installation, testing and
maintenance of services supplying water for domestic
use within buildings and their curtilages.
