CEA 4001 - Intermediate Sprinklers in High Hazard Occupancies

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81

The sprinklers

in

the

region

of

the

opening

shall

be

capable

of

providing

the

minimum

flow

rate

for

sprinklers

in

the

rest

of

the

ceiling

protection.

For

hydraulic

calculation

purposes,

only

the

sprinklers

on

the

longer

side

of the

opening

need

be

considered.

11.4.11 Vertical shafts and chutes

At

least

one

sprinkler

shall

be

installed

at

the

top

of

all

shafts

except

where

the

shaft

is

incombustible

and inaccessible

and

contains

no

combustible

materials

except

electrical

cabling.

In

shafts

with

combustible

surfaces,

sprinklers

shall

be

installed

at

each

alternate

floor

level

and

at

the

top

of any

trapped

section.

11.4.12 Ceiling obstructions

The

use

of

suspended

ceiling

material

below

the

sprinklers

is

not

allowed

unless

the

material

has

been

shown not

to

impair

sprinkler

protection.

Where

sprinklers

are

fitted

below

suspended

ceilings,

the

ceiling

material

shall

be

of

a

type

which

has

been shown

not

to

be

subject

to

partial

collapse

under

incipient

fire

conditions.

11.4.13 Suspended open ceilings

Suspended

open

ceilings,

i.e.

ceilings

having

a

regular

open

cell

construction

recurring

throughout

their design,

may

be

used

beneath

LH

and

OH

sprinkler

systems

not

involving

storage

areas

where

the

following conditions

are

met:

-

the

total

plan

open

area

of

the

suspended

open

ceiling,

including

light

fittings, shall

not

be

less

than

70%

of

the

ceiling

plan

area;

-

the

minimum

dimension

of

the

ceiling

openings

shall

be

no

less

than

0,025m

or no

less

than

the

vertical

thickness

of

the

suspended

ceilings,

whichever

is

the greater;

-

the

structural

integrity

of

the

ceiling

and

any

other

equipment,

such

as

light fittings

within

the

volume

above

the

suspended

ceiling,

shall

not

be

affected

by operation

of

the

sprinkler

system.

sprinklers

shall

be

installed

as

follows:

-

sprinkler

spacing

above

the

ceiling

shall

not

exceed

3m;

-

vertical

separation

between

any

conventional

or

spray

sprinkler

deflector

and the

top

of

the

suspended

ceiling

shall

not

be

less

than

0,8m.

This

distance

may be

reduced

to

0,3m

if

flat

spray

sprinklers

are

used;

-

supplementary

sprinklers

shall

be

provided

to

discharge

below

light

fittings

or similar

obstructions

exceeding

0,8m

in

width.

Where

obstructions

within

the

ceiling

void

are

likely

to

cause

significant

interference

of

the

water

discharge they

shall

be

treated

as

walls

for

the

purpose

of

sprinkler

spacing.

11.5 Intermediate sprinklers in High Hazard occupancies

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