174
L.2.2 Hydraulic design
L.2.2.1
ESFR
sprinkler
installation
shall
be
fully
hydraulically
calculated
in
accordance
with
annex
G1
and
G3.
L.2.2.2
The
design
area
of
operation
shall
consist
of
an
area
with
a
minimum
of
12
ceiling
sprinklers
or minimum
90
m
2
whichever
is
the
greater.
This
design
area
of
operation
shall
be
the
hydraulically
most unfavourable
area
and
may
include
up
to
6
additional
sprinklers
within
the
same
area
(e.g.
under
obstructions). The
minimum
operating
pressures
are
stated
in
Table
L1.
The
water
supply
shall
be
capable
of
providing
the
demand
flow
for
at
least
60
min.
L.2.2.3
For
hydraulic
calculation
purposes,
4
sprinklers
shall
be
assumed
to
operate
on
each
of
3
range
pipes. When
range
pipes
have
less
than
four
sprinklers,
all
the
sprinklers
on
the
range
pipe
shall
be
assumed
to
operate and
the
number
of
ranges
involved
shall
be
increased
until
a
total
of
12
sprinklers
are
assumed
operating.
L.2.2.4
Where
ESFR
sprinklers
are
installed
beneath
mezzanines
of
4,5m
height
from
the
floor
or
less,
at
least
6
ESFR
sprinklers
shall
be
assumed
to
operate
(three
ESFR
sprinklers
on
each
of
two
ranges)
at
an
operating pressure
of
at
least
3,5
bar.
NOTE:
where
standard
sprinkler
protection
is
employed
beneath
mezzanines
of
4,5m
height
or
less,
the
area
of operation
and
design
density
shall
comply
with
the
appropriate
requirements
of
Section
6
-
Hydraulic
design criteria.
ESFR
sprinklers
shall
be
used
beneath
mezzanines
which
are
higher
than
4,5m;
twelve
ESFR
sprinklers
shall
be
assumed
to
operate
(four
sprinklers
on
each
of
three
ranges).
L.2.2.5
Sprinklers
beneath
walkways,
conveyors,
obstructions
and
mezzanines
shall
be
taken
into
account
when designing
the
water
supplies,
in
accordance
with
table
L2.
Table 62: Sprinklers design beneath obstruction (L2)
Obstructions within the design area of
operat
ion
Maximum number of additional sprinklers to be
added
to the ceiling sprinkler water supply
uirements
Obstructions less than 3m width
2 sprinklers operating at 3,5 bar (K=200) at 1,4 bar
(K=
360)
Obstructions greater than 3m width such as
walkwa
ys and conveyors
4 sprinklers operating at 3,5 bar (K=200) at 1,4 bar
(K=
360)
6 sprinklers operating at the design pressure, (see
table
L1).
OTE 1: Providing:
) open-fronted mezzanines are fitted vertically with screens which extend at least 1,2m below t
ing are of non-combustible construction and fit tightly against the underside of the ceiling;
) a clear aisle beneath the screen of at least 0,6m wide each side of the screen centre-line is
intained; additional sprinklers need not be added to the water supply requirement.
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