Acetylene Cylinder Incidents

8/18/2019 Acetylene Cylinder Incidents

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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:



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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

Date post:	06-Jul-2018
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Acetylene Cylinder Incidents

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