CEA 4001 - Page 136

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G.2.3 Light Hazard LH
G.2.3.1 The size of range pipes, and terminal distribution pipes downstream of the design point shall be
as given in Table G6.
T
Table 42: Range pipe diameters for LH installations (G6)
Pipes
Nominal pipe size
mm
Maximum number of
sprinklers
on range pipes
All range pipes and
terminal
distribution
pipes
20
25
1
3
It is permitted to install a 25mm diameter pipe between the design point and the control valve
set if a hydraulic calculation shows this to be possible. However, if the 2 sprinkler point is the decisive
one, a 25mm pipe shall not be installed between the 3
rd
and 4
th
sprinkler.
G.2.3.2 All pipework between the main control valve set and the design point at each extremity of an
array shall be sized by hydraulic calculation using the values in Tables G7 and G8.
Table 43: Maximum friction loss between control valve set and any design point – LH (G7)
Number of sprinklers on a
range or in a room
Maximum friction loss
including changes
in
direction (see Note
to
table)
bar
Range and distribution pipe
loss, see :
≤ 3
0,9
Table G8 columns 2 and 3
≥ 4
0,7
Table G8 column 3
≥ 3 in a single line, in a
narrow room or
range
at a roof apex
0,7
Table G8 column 3
NOTE: in buildings with two or more floors, the pressure loss may be increased
on each floor by an amount equivalent to the static pressure between
the
level of the sprinklers concerned and the level of the sprinklers on
the
highest floor.
G.2.3.3 If there are more than 2 sprinklers on a range pipe, the pressure loss between the 2 sprinkler
point and the distribution pipe shall be determined by using the pressure loss given in column 2 of Table
G8. The pressure loss in the distribution pipe between this connection and the control valve set shall be
determined by the pressure loss per metre given in column 3 of Table G8.
NOTE: figure H3 shows an example of pipe layout in LH with design points from which the piping shall be
fully
calculated.