Element 6 - Fire Safety
Element 6 - Fire Safety
Element 6 - Fire Safety
6
FIRE SAFETY
Q1. Give definition of fire and identify key components of fire triangle?
Fire is a chemical reaction know as combustion which occurs when fuel and oxygen are brought together
with sufficient heat to cause ignition.
Key Components: The fire triangle represents one of the three elements – namely, fuel, oxygen and a
source of ignition, heat or energy – that must be present for combustion to occur.
Q3. Identify sources of ignition that may cause a fire to occur, and give a typical workplace example of
each?
i. Electricity, such as arcing or overheating due to faulty wiring, poor connection or excess
current.
ii. Chemical Reaction, such as spontaneous combustion or exothermic reaction.
iii. Hot Work, such as welding or cutting.
iv. Naked Fumes, such as propane, butane.
v. Friction caused by inadequate lubrication of machinery.
vi. Hot Surfaces, such as those on cooking or heating appliances.
Q4. In relation to classification fires, give an example of a material (fuel) that falls within each of class
A, B, C, D, F?
Class A – All solid materials, usually organic in nature i.e. wood, textiles, paper and plastic.
Class B – All flammable liquids and liquefiable solids such as petrol, oil, paint or wax.
Class C – Gases or liquefied gases, such as natural gas, LPG, propane, butane and acetylene.
Class F – High temperature cooking oils used in large industrial catering kitchens and restaurants.
Q5. Outline methods of heat transfer?
Conduction:-
It is a mode of heat transfer, in which heat is transferred from one molecule to another without actual
movement of molecules, the atoms of molecules collide with neighboring atoms and thus transfer the
heat.
Heat is transferred through solids like metal beams and pipes to other parts of the building act as a source
of ignition there, without burning the material through which it is transferred.
Convection:-
Heat is transferred through the movement of molecules of the material such as in gas. When a gas in
heated it expands and becomes less dense, the hot gases rise up and travel through voids and ducts to
remote parts of a building, and raise the temperature.
Radiation:-
Radiation involving the emission of heat in the form of infra-red radiations which can raise temperature
of adjacent materials so that they reach their ignition temperatures or flash points.
Direct Burning:-
Direct burning is where the flames come into contact with combustible materials, e.g. burning furniture
flames can come into contact with next pieces.
Fire Triangle is very useful tool in identifying the potential fire situations. For a fire to occur it need source
of ignition, fuel and oxygen. If source of ignition and fuel are kept apart, removed or minimized then the
risk to people business is minimized. At first identify the possible sources of ignition and sources of fuel
and oxygen.
Identify any staff or persons who are specifically at risk. For example when sleeping accommodation is
provided near worksite, or any visitors, contractors, general public or disabled person are allowed in
premises.
After identification of hazards and the people particularly at risk, now evaluate the hazards and degree of
risk involved for the people. It is good idea to classify the categories such as low risk, normal risk and high
risk. The ideal step is to remove the hazard altogether so the risk arising out of it eliminated, when this is
not possible replace the hazard with a safer alternative, or the hazard can be segregated.
Now check on control measures that are already exist e.g. means of escape and emergency lighting.
Fire fighting equipment, emergency procedure and means of mitigating the effects of fire or additional
controls are needed.
The hazards identified, people who are at risk, what and where actions are to be taken, conclusion of
assessment and date of assessment.
In the light of assessment there must be clear plan how to prevent the fire and how people be kept safe
in case of fire, coordinate with others if the workplace is shared. Staff must be trained enough so that
they can take right actions in case of fire occurrence.
Fire risk assessment is not a one off procedure, this should be continuously monitored to ensure that
existing fire safety arrangements and risk assessment remain realistic. The assessment should be reviewed
if there is a significant change of work activity, place material used or stored.
Q7. Outline factors to be addressed when carrying out a fire risk assessment?
i. The factors to be assessed while carrying out a fire risk assessment such as the type of work
to be carried out;
ii. The no. of people involved in work activity, their competence level and especially any training
they have received regarding fire;
iii. The quantity of flammable and combustible materials used or stored in the workplace;
iv. The size of the workplace and no. of people to be evacuated including particular groups at
risk like visitors, contractors, young as well;
v. The escape routes and exits, the travel distance and also the emergency lighting
arrangements in place;
vi. Identification of possible ignition sources;
vii. The means of raising the alarm and positioning and the audibility of alarms provided;
viii. Means of making contact with emergency services;
ix. The adequacy and positioning of fire fighting equipment and its access;
x. The procedures for maintenance of equipment;
xi. Emergency signs; Fire assembly points;
xii. Personal training in emergency response procedures and the environment of workplace.
Q8. Outline precautions to reduce the risk of fires being caused by electricity in the workplace?
Q9. Outline EIGHT ways of reducing the risk of a fire starting in a workplace?
Q10. Outline practical ways of achieving an adequate level of compartmentation within a building?
Q11. With respect to the design feature of a building. Identify a types of emergency warning systems
that can be installed in building to aware all workers to evacuate the building?
i. Any combustible – fuels such as paper, wood, cardboard and highly combustible fuels such
as thinners, solvents etc.
ii. Any unsafe procedures or act – persons undertaking unsafe acts such as smoking etc.
iii. Any unsafe condition – these are hazards that may assist a fire to spread in the workplace.
iv. Bad housekeeping – responsible of many small fires starting and spreading over the premise.
Q13. Outline the measures necessary to prevent or control the risk from fire?
i. The workplace is equipped with appropriate fire-fighting equipment, fire detector and alarms.
ii. Appropriate measures are taken for fire-fighting, the maintain and training of workers and
the arrangement of contacting with external emergency services.
iii. Emergency routes are kept clear and comply with any rules relating to routes, doors and signs.
iv. There must be a suitable system of maintenance for fire precautions related to workplace
procedures in general, and to specific equipment and devices which must be kept in good
working order.
Q14. Outline the control measures to minimize the risk of fire in a workplace?
Key points for fire prevention is to eliminate any hazard or reduce it by the substitution of less hazardous
material.
Another control is the control of ignition sources like adoption of “non-smoking” policies where smoking
is permitted, sufficient metal ashtrays should be provided.
(b) Machinery:-
There should be regular inspection of all machinery and equipment, with checks on the proper
lubrication of bearings and correct tensioning of drive belts to prevent friction and
overheating.
i. Waste bins are emptied regularly so that there is no accumulation of combustible materials;
ii. Stairs, benches are regularly cleaned and kept free of litter and rubbish;
iii. Safe disposal of all waste materials is arranged;
iv. “Unofficial” rubbish must be banned;
v. Training required for all workers and that for those with special responsibilities and
coordination and cooperation with other employees who might be affected if a fire occurred.
Q16. Outline how structural features of building can help prevent spread of fire and smoke?
The structural features of the building that help prevent spread of fire and smoke such as,
i. Automatic fire resistant doors, a closed door may restrict fire spread by holding back fire and
smoke.
ii. Fire resistant separation wall restrict fire spread between different compartments where
different activities taking place.
iii. Another significant feature is the compartmentation which are designed to keep a fire in as
well as to keep a fire out.
iv. The fire proof sealants, fire resistant closing of all structural joints and gaps.
v. Sealing off completely in the case of high deformation during fire.
vi. Fire pipe sleeves metal pipe sleeves with inside layers of building material which foams up in
case of fire and close pipes.
vii. Cable ducts, fire protection ducts to protect cables from fire.
i. Smoke detectors
ii. Radiation detectors
i. Check all areas in the building to ensure that everyone knows that an evacuation is in progress
and to help where necessary.
ii. Give special assistance to disabled and inform.
iii. Fire marshal is responsible for coordinating the fire evacuation plan.
iv. He should organize fire instruction, training, drills.
v. He should be known to workers and they should clearly identifiable at the time of emergency.
vi. Ensuring that fire escape routes are kept open and clear at all times.
vii. Conducting the roll call at the assembly area.
viii. Meeting the fire services on arrival and informing them of all relevant details.
Q21. Outline requirements to ensure the safe evacuation of persons from a building in the event of a
fire?
i. The provision of means for detecting the fire and for raising the alarm;
ii. An acceptable distance to the nearest available exit;
iii. Escape routes of sufficient width and fire protected;
iv. Clear signing of escape routes;
v. The provision of emergency lighting;
vi. Escape routes kept clear of obstructions with exit doors unlocked and fire doors closed to
prevent the spread of smoke;
vii. The provision of fire fighting equipment;
viii. The appointment and use of fire marshal;;
ix. Procedures for the evacuation of the disabled, children and visitors;
x. The identification of safe assembly point and the need to practice the evacuation plan at
regular intervals.
Steel frames; Reinforced concrete frames; Timber; Bricks; Building blocks; Building boards; Stone; Glass;
Insulating material; Lime; Paint; Plastics.
Air through the ceiling, floor voids and openings around pipe work can allow the air to feed the fire and
assist in the spread of it. Debris should not accumulate in voids and if necessary such openings should be
bonded or fire stopped.
There must be some facility to stop the ventilation ducts or gaps around, the doors by using baffles, self-
closing doors or some materials which can be expandable subjected to heat.
i. Rotary Gongs – which are sounded by turning a handle around the rim of gong.
ii. Hand Strikers – iron plates suspended from a wall usually striked by metal bar.
iii. Hand bells
iv. Whistles
v. Air-horns.
i. By sensing the presence of smoke or other fumes (often invisible) given off by combustion.
ii. By detecting the presence of flame and a degree of illumination.
iii. By sensing heat – rate of rise in temperature.
Ionization Devices:-
Which are sensitive in the early stages of a fire when smoke particles are small, but their sensitivity tends
to drop as particles grow in size. This detector may mistake dust for smoke resulting a false alarm.
Optical Devices:-
Which are effective in situations where there is dense smoke (i.e. large particles) which obscures or
changes the normal levels of light in the protection area.
Radiation Detector:-
The flame of a fire emits visible light, also ultra violet and infra-red radiations. Flame detector operate on
the basis of sensing the presence of those forms of radiations.
They are capable of rapid detection but effectiveness depends on detector having a clear view of all parts
of protected area.
Heat Detector:-
(a) Fusion:-
Where special alloys melt, either break or make a circuit and round an alarm, with the alloys requiring
replacement each time the detector operates.
(b) Expansion:-
Where a contained metal, air or liquid sensor expands to create a circuit and sound the alarm. They usually
reset themselves after operation when cooled.
i. Water – Red
ii. Chemical Foam – Cream
iii. Carbon Dioxide – Black
iv. Dry Chemical Powder – Blue
i. Hose Reels
ii. Fire Blankets
iii. Automatic Sprinklers
iv. Drenchers
v. Hydrants and Foam Inlets
Extinction by this process is known as starvation. This can be achieved by taking the fuel away from the
fire or a gas supply may be turned off.
(ii) Removing the Oxygen:-
Extinction by this process is knows as smothering. This can be achieved by either allowing fire to consume
all the available oxygen, while preventing inward flow of any more oxygen or adding an inert gas to
mixture or by use of a blanket of foam or a fire blanket.
Extinction by this process is known as cooling. Cooling with water is the most common means of fighting
a fire.
Q32. Explain which type of extinguisher can be used on which types of fires?
Water is the most effective means of extinguishing Class A fires, and may also be used as a spray on Class
B fires involving liquids and liquefied solids which as miscible (mix) with water, such as methanol, acetone,
Alcohol.
Foam is a special mixture which forms a smothering blanket over the fire, cutting off the supply of oxygen.
It can be used on Class A and Class B fires involving those which are immiscible (don’t mix) with water like
petrol, diesel, wax, oil.
The powder is sprayed as a cloud over the fire, again acting to smother the supply of oxygen. It can be
used on Class B fires and on small liquefied gas fires within Class C. Specialized dry powder using inert
substances are also used on Class D fires. Powder also effective on fires involving electricity.
Applied on Class A and Class B fires and also on fires involving live electrical equipments.
It works by means of smothering the supply of oxygen. Effective on Class B and also for electrical fires as
gas may enter inside of equipment.
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