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Fire Safety in Warehouses

Uses and Benefits of Sprinklers

Presented by: Stewart Kidd, MA,MSc,FIFireE,FIFSM

PROTECTING PEOPLE, PROPERTY AND THE ENVIRONMENT


What can sprinklers do?

Detect a fire

Sound a local and remote alarm – call the fire

service

Immediately start to fight the fire

Contain the fire – prevent it spreading

Often suppress completely before the arrival of

the fire and rescue service


Sprinklers :

Are very reliable – >95% probability of success

Minimise amount of water used in fighting the fire

Fire hose uses 15 – 25 times more water

Protect lives as well as buildings and contents –

including the lives of fire fighters

Cut damage to 85 – 90% of that in unsprinklered bldg

Ensure speedy return to work

Very cost effective – large insurance discounts

Have a long service life > 30 years

Require only simple, low cost maintenance


Sprinkler Reliability

Where sprinklers were effective:-

• 67% of cases involved only 1 sprinkler operating

• 83% involved 1-2 sprinklers operating

• 89% involved 1-3 sprinklers operating

Source : NFPA Presentation March, 2006 – Lisbon, Portugal


Potential Design Freedoms












Increased compartment size

Flexibility in fire alarm standard

Reduced fire resistance to elements of

structure

Flexibility in provision of travel distances

Reduced formal fire separation

Reduced fire door provision

Improved disabled access / egress

& potential for phased evacuation

Flexibility / Reduction in stair provision

Surface finishes (Internal)

Reduced fire brigade access requirements

Most importantly - a reduction in

prescriptive design


Sprinklers and the Environment

Environment - Water Pollution From a Fire:


1986 Sandoz, Basle Fire –River Rhine contaminated from

Basle to Rotterdam by fire brigade water run-off estimated at

180m 3 /hour

France – Rubber Tyre Fire Tests 2005,

Sprinklered vs. unsprinklered – 10,000m 2 warehouse scenario




33 times less fire water consumption

1200 times less product destroyed by fire

53 times less hazardous chemicals produced and entrained in fire water runoff

Source: FM Global


Fire Safety Philosophies

Three Levels of Approach: -

General – follow AD-B or Technical

Handbooks

Advanced – BS9999

Fire safety engineering – BS pd 7974


General Approach



Applicable to a majority of building work undertaken

within the UK

Compliance with the guidance documents published to

support legislative requirements e.g.:

Scottish Technical Standards

Approved Document B


Fire Safety Engineering



Provides an alternative approach to fire safety &

can be the only practical way to achieve a

satisfactory standard of fire safety in some large

& complex buildings

Detailed guidance on fire safety engineering is

given in BS 7974.


Can be expensive!


Advanced Approach




This is the level for which BS 9999 is provided.

Gives a more transparent and flexible approach

to fire safety design

Uses a structured approach to risk-based

design where designers can take account of

varying physical and human factors.


Concept of BS 9999: 2008

Based on Fire Engineering principles and research

but does not require Fire Engineering knowledge

to use

Design principles are based on RISK associated

with TIME

Extended ‘available safe egress time’ (ASET)

permits extended travel distances etc.


Occupant Behaviour


Occupant Behaviour

Ignition

Untenable Conditions

• Discovery

• Alarm

• Pre-movement

• Escape time


Concept of BS 9999: 2008

Occupancy characteristics

Fire growth rates

Risk profiling

Minimum provision determination

Minimum fire protection measures.

Variations allowed for additional features


Concept of BS 9999: 2008

Minimum package of fire safety measures must

first be established.

Consideration must be given to: -

the hazard posed by occupancy

provision for giving warning in case of fire (AFD ?)

the provision of fire suppression and/or smoke control

systems

overall control and fire safety management


Concept of BS 9999: 2008

Allows for variations of matters such as travel

distances, exit widths etc because of: -





increased level of fire safety management

automatic sprinkler system*

smoke control system

additional fire detection

*Guidance on construction also allows for variations when sprinklers

are installed to BS EN 12845: 2004 systems (to be reissued in 2009)


Occupancy Characteristics

Table 2 Occupancy characteristics

Occ charc Description Examples

A

B

C

Occupants who are awake and familiar with

the building

Occupants who are awake and unfamiliar

with the building

Occupants who are likely to be asleep:

Office and industrial premises

Shops, exhibitions, museums, leisure

centres,

other assembly buildings, etc.

Ci Long-term individual occupancy Individual flats without 24h maintenance

and management control on site

Cii Long-term managed occupancy Serviced flats, halls of residence,

sleeping areas or boarding schools

Ciii Short-term occupancy Hotels

D A) Occupants receiving medical care Hospitals, residential care facilities B)

E C) Occupants in transit Railway stations, airports


Fire Growth Rates

Table 3 Fire growth rates

Category Fire growth rate Examples Fire growth parameter A) kj/s

1 Slow Banking hall, limited combustible

materials

2 Medium Stacked cardboard boxes,

wooden pallets

3 Fast Baled thermoplastic chips,

stacked plastic products, baled

clothing

0.002 9

0.012

0.047

4 Ultra-fast Flammable liquids, expanded

cellular plastics and foam

0.188

A) This is discussed in PD 7974-1.


Risk Profiles

Table 4 Risk profiles

Occupancy characteristic

From table 2

Fire growth rate

Risk profile

A

(Occupants who are awake and

familiar with the building)

B

(Occupants who are awake and

unfamiliar with the building)

C

(Occupants who are likely to be

asleep)

1 Slow A1

2 Medium A2

3 Fast A3

4 Ultra-fast A4 A)

1 Slow B1

2 Medium B2

3 Fast B3

4 Ultra-fast B4 A)

1 Slow C1 B)

2 Medium C2 B)

3 Fast C3 B), C)

4 Ultra-fast C4 A), B)

A) These categories are unacceptable within the scope of BS 9999.

Addition of an effective localized suppression system or sprinklers will reduce the fire growth rate and consequently change the category (see 6.5).

B) Risk profile C may be divided into sub-categories, viz. Ci1, Cii1, Ciii1, etc.

C) Risk profile C3 will be unacceptable under many circumstances unless special precautions are taken.

See note A) re fire suppression/sprinklers!


Sprinklers

Fire resistance for structural elements are

covered extensively and minimum levels

related to the various ‘risk profiles’ are provided

in tables.

The tables allow for these standards to be

changed (relaxed) if sprinklers are installed in

accordance with BS EN 12845 or BS 5306 Part

2 (for existing buildings).


Sprinklers

Distances from site boundaries and other

buildings:


Where a building is provided with sprinklers the

amount of unprotected area may be doubled or the

distances to the boundary for a given amount of

unprotected area may be halved.


BS 9999

Likely to be used in design and build projects

and speculative warehouse projects

Care must be taken by the occupier of such

premises that the statutory fire risk assessment

takes into account not only the people present

but also the fuel load and likely rate of fire

spread


The Truth About Sprinklers

Question: “Aren’t they expensive to install & maintain?”

Answer: “No, sprinklers are extremely cost effective.”

The Facts:






Sprinklers cost between 1.5% & 2.5% of new construction cost

Maintenance of systems generally less than £800/year

Life expectancy is greater than 30 years

Save f&rs time and reduce risks to fire fighters

Reduced insurance premiums (up to 65% is available)

Reduce insurance excess figures – often to £0


The Truth About Sprinklers (2)

Question: “Aren’t sprinklers open to vandalism/accidental discharge?”

Answer: “Not if correctly designed and installed.”

The myths:

‘Systems are likely to be vandalised’:

Design out the risk - most sprinkler protection is concealed out of view above

ceilings.

Use new technology – concealed sprinklers.

Consider location of control valves and mains pipe work.

Vulnerable heads can be fitted with wire cages

‘The water damage is worse than a fire’

Risk of accidental discharge virtually nil (Data suggests fewer than 20 incidents

a year in the UK caused by ladders/fork lift masts)

Average fire controlled by two heads (max 150 litres/minute) - within two

minutes of fire starting – fire service will apply up to 90% more water.

Sprinkler protected buildings can reopen within 24 to 48 hours of a fire



Trained staff can reduce water flow without impairing system protection

Local and remote alarm monitoring can reduce further risks of water damage


What Can Sprinklers Offer?





Detect a fire

Extinguish or control the fire

Raise the alarm locally

Call the fire and rescue service


Fire Safety in Warehouses

Uses and Benefits of Sprinklers

Presented by: Stewart Kidd, MA,MSc,FIFireE,FIFSM

PROTECTING PEOPLE, PROPERTY AND THE ENVIRONMENT

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