PN 376 - Cylinder procedure

Question 1

PN 376 - Cylinder procedure

Describe cylinder colours according to their contents

Answer 1

• Acetylene - maroon
• O2 - white
• Argon - (dark) green
• Nitrogen - black
• CO2 - grey
• Helium - brown

Question 2

PN 376 - Cylinder procedure

Colour classification by hazard property?

Answer 2

• Bright green - INERT
• Red - FLAMMABLE
• Pale blue - OXIDISING
• Yellow - TOXIC
• Yellow/Red - TOXIC (AND/OR CORROSIVE AND FLAMMABLE)
• Yellow/Light Blue - TOXIC (AND/OR CORROSIVE AND OXIDISING)

Question 3

PN 376 - Cylinder procedure

What is the practical behavioural difference between a composite cylinder and one that looks composite but has an alluminium layer?

Answer 3

The alluminium layer will not allow the gas to escape.

Question 4

PN 376 - Cylinder procedure

1.2 - A cylinder can be defined as…

Answer 4

A cylinder can be defined as any vessel containing a gas or liquid under pressure

Question 5

PN 376 - Cylinder procedure

1.3. - Gases are stored in one of three ways:

Answer 5

• a liquefied form (e.g. LPG),
• as a compressed gas (e.g. oxygen), or, in
• the case of acetylene dissolved in a solvent and stored in special cylinders containing a porous mass within the steel shell.

Question 6

PN 376 - Cylinder procedure

1.4 - Cylinders are constructed in one of 4 ways:

Answer 6

• Welded cylinders: two steel halves welded together around the centre.
• Drawn steel: a single steel skin containing no weld.
• Aluminium cylinders: lighter in weight than steel cylinders and used to contain specialist gases.
• Composite cylinders: a woven “fabric” jacket impregnated with resin and protected by a hardened plastic outer cage. This type of cylinder is mainly used for LPG but can be found with various contents. Occasionally these cylinders can have an aluminium inner lining.

Question 7

PN 376 - Cylinder procedure

1.7 - ICs will be supported in their RA decision making process by the
HMEPO attending the incident. They, in turn, may be supported by…?

Answer 7

…the British Compressed Gas Association (BCGA) competent person

and/or the Scientific Adviser (SA) - where appropriate.

(BCGA CP)

Question 8

2 Hazards and operational considerations

2.1 - All cylinders, regardless of their contents, are at greatest a risk of failure when subjected to direct flame impingement.

As a cylinder is heated the steel or aluminium shell loses its tensile strength which is what temperature:

• [what] for steel
• [what] for aluminium

Answer 8

• 300oC for steel
• 200 – 250oC for aluminium.

All cylinders ultimately fail because the shell reaches a point where its tensile strength weakens and can no longer contain the increasing internal
pressure. In the case of composite cylinders the resin will begin to break down and becomes porous.

Question 9

2 Hazards and operational considerations

2.2 - Where a composite cylinder is involved in direct flame impingement the cylinder may become porous

How would this be evident?

Answer 9

By a substantial increase in the size of the fire as it will be fed by the gas from inside the cylinder.

Question 10

2 Hazards and operational considerations

2.3 - In a situation where a composite cylinder is involved in a direct flame impingement and the cylinder has not yet become porous, the fire can be extinguished and the cylinder cooled.

However, caution should be taken when moving any composite cylinder as the resin may have become weakened to an extent where it may begin to leak when handled. In these situations what is the best course of action?

Answer 10

It is best to leave the cylinder in situ and consult the HMEPO.

Question 11

PN 376 - Cylinder procedure

2.4 - Some composite cylinders cannot be identified as solely composite must be treated as…?

Answer 11

As having an aluminium inner lining. In these situations the cylinder should be treated as a steel cylinder and cooling water should be applied.

Treating them as steel cylinders involves cooling them to ambient temperature.

However, as aluminium will fail at lower temperatures to steel there is a possibility that the cylinder may have already failed and the contents are burning off.

The HMEPO can advise if the contents should be allowed to burn off or if gas dispersal techniques (such as the application of a fine spray) would be appropriate.

Question 12

2 Hazards and operational considerations

2.7 - Why is the initial HZ for steel cylinders 200m?

+

What might be considered to allow this to be reduced?

Answer 12

Any steel cylinder that fails has the potential to project fragments up to 200m.

Therefore, if it is at risk of failure (i.e. it has been substantially heated, or is being subjected to direct flame impingement) an initial Hazard Zone (HZ) of 200m must be implemented around any cylinder.

Acetylene cylinders are designed to fail in ductile mode and split along their entire length. However, if a partial split occurs the cylinder itself can be propelled up to 200m.

+

Full consideration should be given to the availability of substantial cover and how this may allow the initial HZ to be reduced.

Question 13

2 Hazards and operational considerations

2.8 - Where advice or assistance in addition to that being given by the HMEPO is required who might HMEPO consult, on behalf of the IC?

Answer 13

Where advice or assistance in addition to that being given by the HMEPO is required then the HMEPO may consult, on behalf of the IC, with the BCGA CP via Brigade Control.

Question 14

3 Preplanning

3.1 - Station personnel should gather information on the risks on their own stations ground to locate premises which may contain cylinders and what types are likely to be present. This information may be included in:

(3)

Answer 14

• 7 (2)(d) visits.
• Local knowledge.
• Operational risk database on the mobile data terminals (MDT).

Question 15

3 Preplanning

3.2 - Actions en route

Once an IC becomes aware that cylinders may be involved in a fire, either by additional information supplied by Brigade Control or by the nature of the premises, on arrival tactics should be carefully considered. Consideration should be given to:

(5)

Answer 15

• A safe route of approach and the subsequent positioning of appliances.
• The possibility of acetylene cylinders being involved.
• The use of the initial hazard zone overlay.
• The surrounding risks that may become involved if a HZ is implemented – railway lines, major roads or public buildings etc.
• Early notification to Brigade Control of an appropriate RVP.
• Any additional information received from Brigade Control or locally.

Question 16

3 Preplanning

3.3 - Actions on arrival

Appliances should be parked in a manner which affords them suitable protection from a cylinder should it fail. ICs should direct appliance drivers to make use of surrounding buildings and structures to protect vehicles and crews. It is important that early consideration is given to what?

Answer 16

An appropriate RVP and approach route

which, once established, should be communicated to Brigade Control for transmission to all oncoming vehicles which form the attendance at the incident.

This prompt action by the IC helps to manage the HZ if required and reduces the potential for oncoming vehicles travelling through any intended HZ.

Question 17

3 Preplanning

3.3 - Actions on arrival

Appliances should be parked in a manner which affords them suitable protection from a cylinder should it fail. ICs should direct appliance drivers to make use of surrounding buildings and structures to protect vehicles and crews. It is important that early consideration is given to what?

Answer 17

An appropriate RVP and approach route

which, once established, should be communicated to Brigade Control for transmission to all oncoming vehicles which form the attendance at the incident.

This prompt action by the IC helps to manage the HZ if required and reduces the potential for oncoming vehicles travelling through any intended HZ.

Question 18

4 Operational procedure

4.3 - What should initial crews try to establish that will determine the appropriate course of action?

+

What should crews pay particular attention to establishing?

Answer 18

Initial crews discovering a cylinder should make every effort, without exposing themselves to un-necessary risk, to identify:

• the type,
• size,
• contents,
• location and
• number

​of any cylinders involved

+

In particular, crews should attempt to identify if the cylinder is acetylene or not

Question 19

4 Operational procedure

4.5 - Once cylinders have been confirmed at an incident the IC should send an informative message. Give an example…

Answer 19

“From…………….

At…………….

1 x industrial unit 20m x 20m, 15% alight, 1 x 85Kg acetylene cylinder confirmed involved, cylinder procedure being implemented”.

Question 20

4 Operational procedure

4.6 - Once cylinders have been confirmed the IC must carry out a risk assessment. What will determine the ICs subsequent actions?

Answer 20

• content
• number
• location
• condition of the cylinder(s)

Question 21

4 Operational procedure

4.7, 4.8 - When can it be considered that the cylinder is in no immediate danger of failing and therefore is NOT necessary to implement a 200m hazard zone?

Answer 21

If following a dynamic risk assessment the IC can determine that all of the following can be established:

• The fire has been extinguished.
• The cylinder(s) are definitely not acetylene.
• All the cylinders present have been located.
• The cylinders involved are receiving direct cooling.

Following a risk assessment, only a cordon around the incident sufficient to maintain a safe system of work (SSOW) is required.

If the IC is unable to determine all of the four factors then the appropriate (acetylene/non-acetylene) cylinder procedure MUST be implemented.

Question 22

4 Operational procedure

4.10 - Any cylinders that have not been involved in the initial fire, but are at risk of becoming involved, should be removed to a place of safety. Firefighters need to remain aware of their surrounding and ensure cylinders are moved safely.

Visual indicators that a cylinder has not been involved could include:

(3)

Answer 22

• Paper labels and plastic rings are intact.
• The paintwork has not been blackened or blistered.
• The supply hose pipes are undamaged.

Question 23

4 Operational procedure

41.4 - Secondary actions non–acetylene

Can crews work inside a hazard zone?

+

What level of PPE is required when working within 25m of a heated cylinder.

Answer 23

A HZ is not an exclusion zone; crews may work in this area following a risk assessment by the IC.

When working within the HZ crews must work behind substantial cover where available and be wearing full structural fire fighting PPE (fire kit, fire hood, gloves).

Where crews are working within 25m of a heated cylinder BA should also be worn.

Question 24

4 Operational procedure

4.15 - Secondary actions non–acetylene

Once cylinder procedure has been implemented, the IC should then send an informative detailing…?

(5)

Answer 24

• Actions taken.
• The number of evacuees.
• The HZ size and road closures.
• The RVP and approach route.
• The tactical mode.

Question 25

4 Operational procedure

4.16 - Secondary actions non–acetylene

Once the fire has been extinguished, crews should continue to cool the cylinder(s) until…

+

What happens to the HZ and what info passed to control?

Answer 25

…it is returned to ambient temperature as assessed with a TIC and checked to establish that the cylinder is not leaking (observe for sounds of gas escaping, or bubbling when water passes over the leak);

+

The HZ, if implemented, can then be removed. The IC should then send a message stating the highest recorded temperature, hazard zone removed and the tactical mode.

Note: It is not necessary to state the temperature of all the cylinders, only the highest recorded.

Question 26

4 Operational procedure

4.17 - Acetylene

Actions re HZ if confirmed as ecetylene or cannot determine?

Answer 26

If the cylinder(s) has been identified as acetylene, or if the IC either suspects that the cylinder may be acetylene or cannot determine the cylinder contents, the IC should implement a HZ of 200m making use of all substantial cover to reduce the zone where possible.

Question 27

4 Operational procedure

4.19 - Acetylene

To raise the cylinder temperature to 300oC would require direct flame impingent. At these temperatures crews could expect to see signs of damage such as:

+

Cylinders not showing these signs of heat damage indicate what?

Answer 27

• paint blistered,
• labels burnt,
• plastic rings and/or rubber hose melted.

+

Cylinders not showing these signs of heat damage are unlikely to be experiencing decomposition of the cylinder contents.

Question 28

4 Operational procedure

4.20 - Acetylene

Acetylene cylinders which have been heated above 300oC but have not already failed may be at subsequent risk from internal decomposition (i.e. have the potential to reheat after being cooled). However, what will significantly reduce, if not remove, the risk of failure.

There is no evidence that any acetylene cylinder has ever subsequently failed after receiving substantial cooling (1 hour).

Answer 28

substantial cooling (of 1 hour)

There is no evidence that any acetylene cylinder has ever subsequently failed after receiving substantial cooling (1 hour).

Question 29

4 Operational procedure

4.23 - Acetylene

The wetting test in conjunction with a thermal image camera (TIC) is known as the…?

Answer 29

cylinder assessment process (CAP)

Question 30

4 Operational procedure

4.24 - Acetylene

When can the HZ can be removed?

Answer 30

Once an acetylene cylinder has passed the CAP the HZ can be removed.

Question 31

4 Operational procedure

4.24 - Acetylene

What happens if a cylinder fails the CAP?

Answer 31

Where a cylinder fails the CAP which is indicated by the presence of a hot spot on the cylinder wall a further 1 hour cooling should be applied;

the cylinder should be reassessed using the CAP (repeat the cooling and assessment process until the cylinder passes the CAP).

Question 32

4 Operational procedure

4.24 - Acetylene

What happens when a cylinder passes the CAP?

Answer 32

When the assessment has been passed the cylinder is at no further risk of failure, the responsibility should be returned to the owner/occupier, who should be advised to contact the cylinder manufacturer using the Competent Person (CP) scheme.

A Form No 6104 acetylene cylinder handover form should be completed.

Question 33

4 Operational procedure

4.25 - Acetylene

Describe the CAP process.

Answer 33

The CAP (Cylinder Assessment Process) consists of:
Stopping the application of cooling water after one hour:
• Monitor the cylinder with a thermal imaging camera (TIC) and record temperature.
• Observe for any violent steaming* or rapid drying out of the cylinder surface.
• Leave cooling water off for 15 minutes.
Apply a momentary spray of water to the cylinder then shut off.
The above process must be completed 4 times (a total of 1 hour).
*Violent steaming – It should be noted that this steaming would be the equivalent of when red hot metal is plunged into cold water and not a gradual drying out consistent with the atmospheric conditions of the day. The critical temperature is around 300° centigrade. At these temperatures any water will violently react and boil off the surface.

Question 34

4 Operational procedure

4.25 - Acetylene

When carrying out the CAP, IC’s should be aware that on hot days the cylinder may steam off (as maybe observed when washing a car on a hot day) this does not mean that it has necessarily failed the test. A TIC should then be used to assess the temperature of the cylinder.

How can crews use the TIC effectively?

Answer 34

Crews should be advised to make comparisons between the cylinder surface and other metal surfaces in the surrounding area to observe the effect of the climate.

Question 35

4 Operational procedure

4.26 - Acetylene

Can the IC decide to air cool instead of water cool?

Answer 35

The air-cooling should be applied to the cylinder for an hour as with water cooling, however, this decision should only be taken in consultation with the HMEPO.

Question 36

4 Operational procedure

4.29 - Acetylene

HMEPOs must maintain a log at acetylene cylinder incidents, recording:

(5)

Answer 36

• The location of the cylinder.
• When cooling commenced and is due to finish (also recorded by the IC if cooling starts before HMEPOs arrival).
• When CAPs have been carried out and the temperature readings.
• All decisions taken during the cooling process.
• Any requests for the CP and their subsequent advice and actions.
Note. This log must be “handed over” to any subsequent HMEPOs attending. At protracted incidents where a HMEPO is no longer required, this log must be passed to any subsequent IC’s. It is the responsibility of the final IC to retain this log and forward it to the initial HMEPO that attended.

Question 37

4 Operational procedure

4.31 - Cylinder alight at valve group – all cylinders

When a cylinder is found to be alight then…

+

Considerations

Answer 37

…the flame can usually be extinguished and the valve shut down. However, there are considerations which need to influence the risk assessment process before this option is selected:

+

• build up of gases in enclosed area
• cylinder heated? Cool first (take care not to extinguish fire)

Question 38

4 Operational procedure

4.45 - Hand over of incident

Once the incident has been brought to a conclusion the cylinder should be handed over to:

Answer 38

a responsible person. This may be the cylinder manufacturer, the owner/occupier of the site, local authorities etc. where there is doubt about who to hand the cylinder over to then the HMEPO can advise or arrange collection – via the BCGA CP