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General Properties:
• Colourless
• Highly flammable
• Garlic-like odour.
• It is an unstable gas at ambient temperature and
pressure
• Significantly more so at elevated temperature andpressure
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USES
Garages
Engineering workshops
Laboratories
Construction and demolition sites
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USES CONT’D
Scrapyards
Factories
Steelworks
Domestic property
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IGNITION SOURCES
Direct flame
A static discharge from a human finger or clothing
Sparks from aluminium rubbing on rusty steel
Friction
Shock
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Withdrawal of acetylene results in gas being
released from the solvent as the cylinder pressure
falls. For each bar of pressure the acetone solvent
absorbs 25 times its own volume of acetylene.Larger acetylene cylinders contain approximately
20 ltrs. of acetone and therefore contain
approximately 7,500 litres of dissolved acetylene in
solution when nominally charged to 15 Bars. 20 litres (acetone)
X 25 (volume acetylene/bar)
X 15 bars (gauge pressure)
= 7,500 litres dissolved acetylene.
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Accordingly, an empty cylinder still represent a
hazard in a fire
Regardless of the type and location of the
pressure release device, its operation must NOTbe considered as a signal that the cylinder is in
a safe condition
A cylinder that has been heated will be sensitive
to shock
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CYLINDER TESTS
Drop test
Elevated temperature test
Backfire test
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SIGNS OF POSSIBLE HEATING
Do any of the cylinder labels appear burnt?
Are any of the plastic rings around the cylindervalve melted in any way?
Is the cylinder paintwork burnt or blistered?
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OPERATIONAL SAFETY TEST
Getting a clear view of the cylinders from a safe
location, protected from any possible blast
Spraying sufficient water on to the cylinder to wet
the entire surface of it
Stopping the spray and looking for signs of steam
rising from the surface of the cylinder
If steam is not seen rising, does the wetted cylinder
surface dry out quickly?
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CIRCUMSTANCES THAT INITIATEDECOMPOSITION
One or a combination of the following circumstances:
Flashback from a cutting/welding torch into thecylinder
Hot work residue which can burn into the supply
tubes and burn back to the cylinder
Cylinders in the vicinity of a fire.
Cylinders that have otherwise been subjected to
direct or indirect heat.
A hot cylinder that is dropped or otherwise suffers
severe mechanical shock may potentially fail
catastrophically.
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An acetylene cylinder that has been heated and is
leaking gas presents the greatest danger of
catastrophic failure. This is due to the fact that freshacetylene will be released by the acetone. This fresh
acetylene will travel through the internal mass of the
cylinder and if a reaction is taking place may provide
additional fuel for decomposition, ultimately
increasing the rate of reaction and potential for
catastrophic failure.
There is at present no practical reliable means of
detecting decomposition deep within an acetylene
cylinder.
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CATASTROPHIC FAILURE
These hazards include:
A blast pressure wave.
Fireball of up to 25 metres.
Cylinder may be thrown up to 150 metres.
Large fragments which have high loopingtrajectories.
Flying shrapnel, valve assembly, carrying trolleyand other ancillary equipment which may bethrown up to 200 metres.
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CATASTROPHIC FAILURE CONT’D
Flying glass and other structural material.
Structural damage to buildings in the vicinity.
The spread of asbestos particulates either from the
filler mass or building materials.
THE RANGE OF POSSIBLE IN
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THE RANGE OF POSSIBLE IN
JURIES MAY INCLUDE:
Death
Blast injuries
Flash burns
Permanent hearing damage
Concussion
Bruising
Post-incident trauma
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PROBLEMS WITH ESTABLISHING CORDON:
If necessary, evacuating large numbers of the
public from places of entertainment, homes and
places of work.
Stopping traffic on railways or road networks,
leading to congestion and frustration/anger.
Attracting a crowd of onlookers.
Dealing with aggrieved business people.
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Increased environmental damage from firewater run off
Overrunning of drains and interceptors, spreading
hazardous substances into the area of operations.
Concerns from the community regarding excess waste of
water supplies.
Run off into local water courses.
Flooding of low-lying areas in the vicinity.
The creation of concealed fall/trip hazards.
HAZARDS/PROBLEM ASSOCIATED WITHAPPLICATION OF WATER INCLUDE
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MULTI-AGENCY APPROACH
Police
H.S.E.
Environment Agency
Acetylene Cylinder Suppliers
Users and other Local Authority
Agencies that will be affected by this type ofincident.
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LIAISON
Liaison will ensure:
A possible reduction in the number of acetylenecylinder incidents
All parties involved understand the implications ofsuch an incident
The safe and effective management of the incident
The safe and effective handover of affectedcylinders.
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Acetylene cylinders that are suspected of having
been affected by heat should not be approached
or moved under any circumstances
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IMMEDIATE STEPS
Establish if the cylinders have been exposed to
heating
Establish the identity of the cylinder(s) concerned
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Water cooling is currently the most effective method
of preventing catastrophic failure of an acetylene
cylinder and should be used whenever it can be
implemented without compromising the safety of
Firefighters, i.e. where protection is offered by
suitable shielding.
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Cylinders that have been subjected to severe shock (for example
falling from an upper storey to the ground) should be treated in
the same way as those affected by heat, as there is the potential
to initiate decomposition
The operation of a pressure relief disc or fusible plug with gas
burning off or leaking, indicates an increased likelihood ofcatastrophic failure and should not be regarded as a sign of safety
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There may be circumstances where attempts to apply
cooling water would expose Firefighters to
unacceptable levels of risk that outweigh the benefit
likely to be gained. In such circumstances the
alternative would be to leave the cylinder in situ
without applying water.
An example of this situation is:
Where no shielding is available; and
There is no immediate risk to life.
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Whilst the application of water is consideredto be the most suitable method of cooling acylinder, it is appreciated that the application
of this medium might have to be interruptedor ceased dependent upon the IncidentCommander's dynamic risk assessment. Thisassessment should consider factors such as:
The nature of the incident.
The nature of surrounding/adjacent risks.
The risk to Firefighters providing cooling watersprays.
The adequacy of any shielding.
The nature and effects of any cooling water run off.
The environmental impact.
Whether the cylinder walls are cool.
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Acetylene cylinders should therefore be left in situ fora minimum period of 24 hours following the removal
of any heat source, with cooling water being applied
for this duration where the situation permits.
If it is not possible to continually apply cooling water,
cylinders should be left alone in situ to be cooled
naturally for at least 24 hours.
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LEAKING CYLINDERS
(PRE AND POST FIRE SITUATION)
Where leakage of acetylene gas is suspected, the
possibility of an explosive atmosphere could exist and
therefore the following should be considered:
Evacuation of immediate area.
Elimination/separation of ignition sources.
Water sprays to assist the dispersal of gas.
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CLOSING THE INCIDENT
Acetylene cylinder(s) cannot be considered safe until
at least 24 hours after the removal of any external
heat source or commencement of water or natural
cooling.
If an acetylene cylinder has failed catastrophically forno apparent reason, the Health and Safety Executive
must be notified.
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Only Firefighters involved in fire-fighting operationswill be allowed in the zone until the cylinder is made
safe. If your home is within the zone but you areunwilling or unable to leave for this period, may weoffer the following safety advice:
Do not leave your home for the 24 hour period. If you do leave your home, you may not be allowedback in for safety reasons.
Close your curtains and stay away from any
windows.
Position yourself in a room as far away from theincident as possible.
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Actions on arrival:
Siting of appliances
Gather information to determine likelihood of
acetylene cylinders being involved and heated
Assess potential risk in order to determineoperational actions
Operation of pressure release devices
Determine 200m hazard zone
Consider shielding
Establish Inner Cordons
Consider evacuation
CONSIDERATIONS FOR THE INCIDENT
COMMANDER:
CONSIDERATIONS FOR THE INCIDENT
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CONSIDERATIONS FOR THE INCIDENT
COMMANDER CONT’D:
As the incident develops: Appoint safety officers
If possible apply cooling water
Determine tactical mode; any firefighting
should be undertaken from behind shielding
Use of ground monitors and/or lashed
branches
Wetting test If cylinder remains cool consider reducing
hazard zone
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KEY ACTIONS
Identify initial 200m hazard zone
Carry out Dynamic Risk Assessment withinhazard zone -Type of structure/Topography
Establish Cordons -Public safety, Firefightersafety, Liaise with Police
Apply Water? - Accessibility of cylinder, Publicsafety, Firefighter safety. Environmental impact,
Operational restraints
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KEY ACTIONS CONT’D
Re-assess risk and consider reducing hazard
zone/cordons - Cylinder remains wetted and is notleaking, Shielding
After 24 Hours hand over to occupier/cylinder
owner or other agency - Earlier handover ifsuitable, safe and secure arrangements can be
maintained
Fire Service Incident Closed
Gas supplier to recover
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Prepared by Acting F.S.O. Isaac
Source: Fire Service Manual Volume 2 Fire ServiceOperations
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