Lecture: Fire Safety
Contents:
A. Combustion
B. Ignition Temperature
C. Sources of Ignition
D. Classification of fire
E. Three ways of extinguishing a fire
F. Types of Fire Services Installations and Equipment
G. Portable Fire Extinguishers
H. CAP 59V Factories and Industrial Undertakings (Fire Precautions in Notifiable Workplaces)
Regulations
I.
Fire Prevention Activities
J.
References
K. Useful Address
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A.
Combustion
1.
Combustion may be defined as a chemical reaction accompanied by the evolution of light
and heat. It is only when fuel, oxygen and heat come together in the right proportions that
you have a fire. These three elements make up what is commonly known as FIRE
TRIANGLE or Triangle of Combustible.
2.
Combustible materials exist as solids, liquids and gases. The burning of any substance is
usually accompanied by a flame; and as a flame is produced as the result of the burning of
a gas or vapor, it can be seen that liquids, and solids with minor exceptions, must emit
inflammable vapors before combustion can take place.
3.
A supply of oxygen is required to support combustion and this is usually drawn from the
atmosphere, of which it form about 20 % but in some cases the material themselves
contain sufficient oxygen to maintain combustion when deprived of atmospheric
oxygen.
4.
Most solids and liquids require to be heated above their normal temperature before they
can emit inflammable vapors; and some liquids (e.g. petrol) emit inflammable vapors at
normal temperatures.
B.
Ignition Temperature
The temperatures at which combustion can take place fall into three categories, they are:
1.
Flash Point: The lowest temperatures at which a substances gives off sufficient
inflammable vapor to produce a momentary flash on the application of a small flame.
2.
Fire Point: The lowest temperatures at which the heat from the combustion of a burning
vapor is capable of producing sufficient vapor to sustain combustion.
It will be seen that the difference between flash point and fire point is that the flash point
temperature is only required to produce vapor to enable a momentary flash to take place
whereas the fire point temperature has to be high enough to produce sufficient vapor to
enable combustion to be maintained.
3.
Spontaneous Ignition: The lowest temperature at which the substance will ignite
spontaneously. When the cooling becomes inadequate to dissipate the heat developed,
the material will begin to self-heat and will eventually burst into flame.
C.
Sources of Ignition
Combustible materials may be ignited in various ways:
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1.
2.
3.
4.
5.
Open flame
• e.g. bunsen burners in lab, welding torch, lighting of a match
Electrical sparks or arc
• e.g. static electricity, overloading or supply, short circuit, electric arc welding
Mechanical sparks
• caused by friction, e.g. cutting, grinding
Spontaneous ignition
• certain chemical reactions generate sufficient heat to cause fire; e.g. yellow
phosphorus oxidises very rapidly and ignites on contact with air
Hot surface
• e.g. heater
D.
Classification of fire
1.
Fires involving solid materials
e.g. wood, paper, textiles, etc.
2.
Fires involving liquids or liquifiable solids
e.g. petroleum, solvents, oil, paint
3.
Fires involving gases
e.g. LPG, Town Gas
4.
Fires involving metals
e.g. Magnesium, Sodium, etc.
5.
Fires involving electrical hazards
Remarks:
SECTION 3 of the Dangerous Goods Ordinance declares the following to be DANGEROUS
GOODS’:
‘All explosives, compressed gases, petroleum and other substances giving off inflammable vapours,
substances giving off poisonous gas or vapour, corrosive substances, substances which become
dangerous by interaction with water or air, substances liable to spontaneous combustion or of a
readily combustible nature.’
SECTION 6 of the Ordinance states:
‘Except under and in accordance with a licence granted under this Ordinance no person shall
manufacture, store, convey or use any dangerous goods.’
Which means that with the exception of Explosives (Category 1 Dangerous Goods) which can only
be manufactured or stored as required by the Commissioner of Mines, these goods can only be
used and/or stored in excess of the exempt quantity in accommodation approved and licensed by
the Director of Fire Services.
In the Dangerous Goods (Classification) Regulations, dangerous goods are listed into 10 categories.
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For example; Category 2 – Compressed Gases, Category 5 – Substances giving off inflammable
vapours.
E.
Three ways of extinguishing a fire
1.
Starving
(a) Take the fuel away from the fire. For example, by removing combustible material
from the neighborhood of the fire.
(b) Take the fire away from the fuel. For example, by subdividing the burning material
into smaller fires which may be left to burn out or to be extinguished.
2.
Smothering
(a) By reducing the oxygen which supports the combustion. Allow the fire to consume
the oxygen while preventing inward flow of more oxygen. For examples,
• use of covers or blankets
• use of foam on oil
• use of finely divided particles of dry powder (e.g. sodium bicarbonate)
(b) Add an inert gas to the burning mixture.
3.
Cooling
Cool the heat source. If the rate at which heat is generated by combustion is less than the
rate at which it is dissipated, the combustion cannot persist. In applying this principle to
fire extinction, the first step is to accelerate the speed with which heat is removed from the
fire, thus reducing the temperature of the burning mass and as a consequence the rate at
which heat in lost from the fire exceeds the rate of heat production and the fire dies away.
F.
Types of Fire Services Installations and Equipment
1.
Fire hydrant/hose reel installation
2.
Dry riser
3.
Sprinkler
4.
Automatic fire detection system ( heat/smoke )
5.
Drencher
6.
Manual fire alarm
7.
Fixed inert gas systems ( CO2, BCF, BTM )
8.
Water spray
9.
Portable fire extinguishers
10.
Sliding doors, drop shutters, smoke stop doors
11.
Fireman’s lifts
12.
Exit signs
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G.
Portable Fire Extinguishers
These are appliances designed to be carried and operated by hand. They contain an extinguishing
medium which can be expelled by action of internal pressure and directed onto a fire.
1.
Water type extinguisher
• Use on fires involving wood, textiles and paper.
• Never use water to extinguish an electrical fire. Water is a good conductor, and there is
some concern for electrocution if you use water to extinguish an electrical fire.
• Never use water to extinguish flammable liquid fires. Spread the fire if you try to use
water on it.
2.
Foam type extinguisher
• Use on fires involving flammable liquids, such as gasoline, oil, solvents.
3.
Carbon Dioxide (CO2) gas extinguisher
• CO2 are designed for flammable liquid and electrical fires only.
4.
Dry Powder extinguisher
• Use on most fires, flammable liquids, metal fires or electrical fires.
5.
B.C.F. (BROMOCHLORODIFLUOROMETHANE) extinguisher
• Use on electrical fires, flammable liquids, delicate equipment, important documents.
H.
CAP 59V Factories and Industrial Undertakings (FIRE
PRECAUTIONS IN NOTIFIABLE WORKPLACES) Regulations
Application: These regulations apply to every notifiable workplace.
Doors:
(1)
Every door leading out of a notifiable workplace shall(a) Be maintained in such condition that it can be readily opened and closed at any time;
(b) If it is a sliding door(i) be so designed as to be self-closing, by its own weight or otherwise; or
(ii) be connected to a counterweight by means of a fusible link which shall fuse at a
temperature of not more than 68oC thereby disconnecting the counterweight from the door
so that the door will close;
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(c) if it is not a sliding door, be kept closed by means of a self-closing mechanism which
shall at all times be fully operational and maintained in good working order;
(d) if it is made of metal, be of solid steel with an overall thickness of not less than 3 mm;
and (L.N. 210 of 1985)
(e) if it is made of materials other than metal(i) conform to the standards laid down in *Tables F and G of the Third Schedule to the
Building (Construction) Regulations (Cap 123 sub. leg. A); or
(ii) be in accordance with the specifications shown in the plan approved by the Building
Authority under section 14(1) of the Buildings Ordinance (Cap 123). (L.N. 210 of 1985)
(2)
Every door in a notifiable workplace, other than a sliding door, shall be constructed to
open outwards and shall not when open reduce the effective width of any means of escape(a) from the workplace, if the door is a door leading out of the workplace; or
(b) if the door is a door of a room in the workplace being a room in which more than 10
persons are employed, from the room. (L.N. 210 of 1985)
(3)
While any person employed in a notifiable workplace is within the workplace, whether such
person is working or not, the doors, gates and shutters leading out of the workplace and
the doors of every room in the workplace in which any such person is, shall not be locked
or fastened in such a manner that they cannot be easily and immediately opened from the
inside.
Maintenance of fire escapes:
(1)
The proprietor of every notifiable workplace shall maintain in good condition and free from
obstruction every doorway, stairway and passageway within the workplace which affords
a means of escape from the workplace in case of fire. (50 of 1985 s. 9)
(2)
No person shall wilfully alter, damage, obstruct or otherwise impair any such doorway,
stairway or passageway.
Fire fighting:
1)
The Commissioner may, by notice in writing, require the proprietor of any notifiable
workplace to provide and maintain at that workplace, in addition to any fire service
installation or equipment already in that workplace, means for fighting fire appropriate to
the size, type and nature of the undertaking being carried on, which shall be so placed as to
be readily available for use. (50 of 1985 s. 9)
(2)
The notice given under this regulation shall specify in detail the means for fighting fire to be
provided and maintained, and the time within which the notice is to be complied with.
(3)
The proprietor of a notifiable workplace shall, on being served with a notice under this
regulation, comply with the notice.
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(4)
No person shall wilfully alter, damage, obstruct or otherwise impair any means for fighting
fire provided in accordance with this regulation.
(5)
In this regulation "maintain" (保持) means maintain in an efficient state, in efficient working
order and in good repair.
Smoking:
(1)
An occupational safety officer may, by notice in writing, prohibit smoking in any notifiable
workplace, or in any part thereof, where any inflammable substance or any other substance
or article which in his opinion involves danger from fire is present for the purposes of or in
connexion with, any industrial process or operation, and the circumstances are such that
smoking would give rise to a serious risk of fire. (32 of 2000 s. 48)
(2)
No person shall smoke in any part of a notifiable workplace in which smoking is prohibited
under paragraph (1).
(3)
The proprietor of a notifiable workplace in which smoking is prohibited under paragraph (1)
shall take all reasonably practicable steps to ensure compliance with the prohibition and
shall display in prominent positions within the workplace sufficient number of notices
bearing the words and characters "NO SMOKING 不准吸煙", in letters and characters
not less than 180 millimetres high. (71 of 1989 s. 13)
(4)
All notices displayed in accordance with paragraph (3) shall be maintained in good
condition by the proprietor.
Alterations and additions:
(1)
The proprietor of a notifiable workplace shall not carry out or cause or permit to be carried
out or suffer the continuance of any alteration or addition to a notifiable workplace as it is
shown on the plans of the building approved by the Building Authority under Part II of the
Buildings Ordinance (Cap 123)- (L.N. 210 of 1985; 50 of 1985 s. 9)
(a) that may create a serious risk of(i) the outbreak of fire;
(ii) the spread of fire; or
(iii) the spread of smoke from any fire; or
(b) that may obstruct free passageway to a means of escape from the workplace in case of
fire.
Storage of inflammable substances:
(1)
The proprietor of a notifiable workplace in which any inflammable substance is present for
the purpose of, or in connexion with, any industrial process or operation shall ensure that(50 of 1985 s. 9)
(a) subject to sub-paragraph (b), the inflammable substance is stored in suitable closed
containers and that the containers are kept in a storeroom which is approved for that
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purpose by the Director of Fire Services;
(b) in the case of any room in the workplace where the aggregate quantity of inflammable
substance stored does not exceed 35 litres, the inflammable substance is stored in suitable
closed containers and that the containers are kept in a cupboard or bin constructed of
suitable material. The cupboard or bin shall be situated in a position where it is least likely
that the inflammable substance will catch fire.
(2)
Every container, storeroom, cupboard and bin used for storing an inflammable substance
shall be clearly and boldly marked "Inflammable Substance 易燃物品". This requirement
shall not apply to(a) any suitable small closed container containing not more than 500 millilitres of
inflammable substance; or
(b) any aerosol dispenser in which the amount of inflammable substance contained is not in
excess of either 45 per cent by weight of the total contents or 250 grammes in weight.
(3)
This regulation is in addition to and not in derogation of the Dangerous Goods (General)
Regulations (Cap 295 sub. leg. B).
Source of ignition:
(1)
No naked flame or other means likely to ignite vapour from any inflammable substance
shall be present in any notifiable workplace where a dangerous concentration of vapours
from an inflammable substance may reasonably be expected to be present.
(2)
In any notifiable workplace where a dangerous concentration of vapours from any
inflammable substance may reasonably be expected to be present, all cotton waste and
other material in the workplace which(a) has been used in such a manner as to render it liable to spontaneous combustion; or
(b) is contaminated with any inflammable substance,
shall be deposited as soon as is reasonably practicable in a metal container having a self-closing lid
or be removed without delay to a safe place.
Without prejudice to regulation 10(1), in every notifiable workplace where any naked flame, burner
or furnace is used, adequate precautions shall be taken to prevent the accidental ignition of any
combustible material.
Prevention of escape of vapors:
Where any inflammable substance is present in any notifiable workplace steps shall be taken to
prevent so far as is reasonably practicable the escape of vapours from any such inflammable
substance into the general atmosphere of the workplace.
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Naked flame:
Without prejudice to regulation 10(1), in every notifiable workplace where any naked flame, burner
or furnace is used, adequate precautions shall be taken to prevent the accidental ignition of any
combustible material.
Power to require safety precautions, etc.:
(1)
The Commissioner may, by notice in writing, require(a) that any notifiable workplace shall be provided with such means of escape therefrom in
the case of fire as may be specified in the notice;
(b) that in any notifiable workplace, such measures as may be specified in the notice shall
be taken to reduce the risk of(i) the outbreak of fire;
(ii) the spread of fire; or
(iii) the spread of smoke from any fire;
(c) that in any notifiable workplace, illuminated notices bearing the words and characters "
出 EXIT 路 ", in letters and characters not less than 180 millimetres high, shall be provided
and maintained in good condition at each exit from the workplace. (50 of 1985 s. 9)
(2)
Every notice given under this regulation shall specify in detail the requirements of the
Commissioner, and the time within which the notice is to be complied with.
(3)
The proprietor of a notifiable workplace shall, on being served with a notice under this
regulation, comply with the notice.
Offences:
(1)
The proprietor of any notifiable workplace who contravenes regulation 6(3), 7(3) or 9(1)
commits an offence and is liable to a fine of $50000. (50 of 1985 s. 9; 71 of 1989 s. 13)
(2)
Where in respect of any notifiable workplace regulation 9(2), 10(1) or (2), 11 or 12 is
contravened, the proprietor of the notifiable workplace commits an offence and is liable to
a fine of $50000. (50 of 1985 s. 9; 71 of 1989 s. 13)
(3)
Any person who contravenes regulation 7(2) and any proprietor of a notifiable workplace
who contravenes regulation 7(4) commits an offence and is liable to a fine of $10000.
(3A) Any person who contravenes regulation 5(2) or 6(4) commits an offence and is liable
to a fine of $50000. (L.N. 45 of 1994)
(4)
The proprietor of any notifiable workplace who contravenes regulation 8(1) commits an
offence and is liable to a fine of $200000 and to imprisonment for 6 months. (71 of 1989 s.
13)
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(5)
The proprietor of any notifiable workplace who contravenes regulation 4, 5(1) or 13(3)
without reasonable excuse commits an offence and is liable to a fine of $200000 and to
imprisonment for 6 months. (71 of 1989 s. 13)
I.
Fire Prevention Activities
1.
Inspections
Set up a system of periodic fire inspections for every operation. The function of these fire
safety inspections is to check for proper placement and operation of fire protection
equipment and to correct common causes of fire, such as poor housekeeping, improper
storage flammable materials, smoking, violations, etc.
2.
Hot Work Permits
In an effort to establish some control over operations using flames or producing sparks,
many industrial firms have instituted hot-work permit programs.
Important features of a hot-work permit program include the following:
• Inspect the area where work is to be done, and see how close combustible materials
are to the work area.
• Establish fire watches if hazards warrant them. A fire watch should stay on duty for 30
minutes after all spark-producing equipment has been shut down.
• Provide fire-extinguishing equipment, usually manned by a standby employee.
• Communicate with, and coordinate the activities of, all departments concerned with fire
protection.
• Isolate flammable and combustible materials from sources of ignition.
• Limit unauthorized use of flame- or spark-producing equipment.
3.
Training Employees
Because extinguishers are effective only when fires are in their first stages, ensure that
extinguishers are immediately reachable and promptly used by trained personnel.
Extinguishers are only as good as the operators using them. Therefore, thoroughly train
key workers on each shift.
Fire extinguisher training is intended to teach employees how to stop small fires from
spreading out of control.
4.
Communications
Once a fire has been detected, especially in a potentially disastrous situation, good
communications are necessary (1) as a means of alerting occupants to the emergency and
(2) as a way to mobilize fire protection forces, whether a plant’s fire brigade, the municipal
fire department, or both.
Check list for procedure in the event of fire:
(a)
Vital requirements
• Raising the alarm and summoning fire brigades
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•
•
Immediate attacks
Evacuation
(b)
Normal procedure
• Person discovering fire to report to switchboard or to tell someone else to do so
• Person in charge at fire to decide when to evacuate the buildings
• Telephone switchboard to summon fire brigade, notify management and others
(c)
Emergency Procedure
• Person discovering fire to operate manual fire alarm system and notify switchboard
• Switchboard to call fire brigade
• All others to know what action to take on hearing the alarm
(d)
Information to Fire Brigade
• Nearest entrance to fire
• Location of fire
• Trapped persons and casualties
• Water supplies
• Special hazards in the area
(e)
Immediate Attack
• Those in the area to use the first aid fire fighting equipment.
• Designated person to take charge clear occupants (other than fire fighters) if danger
threatens or their efforts are unsuccessful.
(f)
Alarm System
• Signal to be distinct and audible throughout building
• Capable of being operated from -points throughout building
• Requires effective maintenance and testing
(g)
Escape Procedure
• Fire escape routes
• Everyone to be familiar with normal and alternative escape routes
• Speedy evacuation
• Assembly for roll call
• Departmental manager and deputies responsible for ensuring their departments are
completely evacuated and for calling rolls
(h)
Responsibility
• Allocated in advance to avoid delay & doubt.
• Designated person (if absent, a deputy) responsible in each section for taking charge
at scene of fire.
(i)
Fire Drills
• Practice drills desirable at least twice yearly.
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J.
References
＊
CAP 59V Factories and Industrial Undertakings (FIRE PRECAUTIONS IN
NOTIFIABLE WORKPLACES) Regulations
＊
Fire Services Ordinance, Chapter 95, Laws of Hong Kong and its sub-leg Regulations
＊
Dangerous Goods Ordinance, Chapter 295, Laws of Hong Kong and its sub-leg
Regulations
＊
Timber Stores Ordinance, Chapter 464, Laws of Hong Kong and it sub-leg Regulations
＊
Fire Safety (Commercial Premises) Ordinance, Chapter 502, Laws of Hong Kong
＊
Fire Safety (Buildings) Ordinance, Chapter 572, Laws of Hong Kong
＊
Karaoke Establishments Ordinance, Chapter 573, Laws of Hong Kong
＊
An Introduction to Fire Services (Amendment) Ordinance 2003 & Fire Services (Fire
Hazard Abatement) Regulation
＊
Fire Service ( Installations and Equipment ) Regulations.
＊
Code of Practice for Minimum Fire Service Installations and Equipment and Inspection and
Testing of Installations and Equipment.
＊
Stranks, J. 1997, The Handbook of Health and Safety Practice, 4th edition, ROSPA,
Pitman Publishing, U.K.
＊
Krieger, G. & Montgomery, J. 1997, Accident Prevention Manual for Business and
Industry, U.S.A., 11th edition, National Safety Council.
K.
Useful Address
Fire Protection Bureau, 1, Hong Chong Road, 5/F., Tsim Sha Tsui East, Kowloon.
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