Fires involving chimneys & ducting PN 834

Question 1

Fires involving chimneys & ducting

What is a chimney ?

Answer 1

Chimneys are traditionally non load bearing vertical structures containing an internal flue with a hearth at the base

Question 2

Fires involving chimneys & ducting

What is a flue ?

Answer 2

A flue is a passage for conveying the products of combustion to the outside atmosphere.

Question 3

Fires involving chimneys & ducting

What building services/instalations require a flue ?

Answer 3

Services such as air-conditioning, heating, fume and dust extraction. These services are carried in increasingly complex ducting systems that can run through voids, alongside utilities, across several floors or even through several premises.

Question 4

Fires involving chimneys & ducting

What is the main fire hazard with fires involving chimneys & ducting ?

Answer 4

Poorly designed, constructed and maintained extraction and ducting systems can pose a serious fire hazard. Once started fire and smoke can travel rapidly through a building via these ducting systems.

Question 5

Fires involving chimneys & ducting

What are the main hazards associated with fires involving chimneys & ducting ?

Answer 5

• Working at height
• Falling debris
• Explosion
• Heavy fire loading
• Unexpected fire or smoke spread
• Hearth fires
• Insulating materials
• Electrical extraction systems or filters
• Damage control
• Unauthorised building works:

Question 6

Fires involving chimneys & ducting

What are the working at height hazards ?

Answer 6

It may be necessary to tackle fires in chimneys and ducting from the roof of a building, this carries with it all the hazards associated with working at height. Internal ducting can be run at height inside premises and accessing this ducting presents similar working at height hazards.

Question 7

Fires involving chimneys & ducting

What are the hazards of falling debris ?

Answer 7

Chimney linings can spall away from the flue and fall internally into the hearth as can accumulations of soot, ash and dust. Brickwork and chimney pots can become unstable and fall to the ground during a fire. Chimney pots have also been known to break up explosively on the application of water.

Question 8

Fires involving chimneys & ducting

What are the explosion hazards ?

Answer 8

Where ducting is used for the purpose of extracting dust, fumes or flammable gases, the presence of a fire or even a single spark can lead to an explosion.

Question 9

Fires involving chimneys & ducting

What hazards could be present from heavy fire loading ?

Answer 9

Fires in ducting are often associated with poor housekeeping or maintenance. This can lead to the accumulation of large quantities of grease and fat in ducting system which can in turn lead to rapid and unpredictable fire development

Question 10

Fires involving chimneys & ducting

What are the potential hazards caused by unexpected fire or smoke spread ?

Answer 10

Fires in chimneys can spread through smouldering joists or concealed voids into unexpected areas of a property or adjacent properties. The path ducting takes through a building can be complicated and radiated heat from a fire in ducting can also lead to lateral or vertical fire development

Question 11

Fires involving chimneys & ducting

What are the potential hazards asssociated with hearth fires ?

Answer 11

Building modernisations and conversions can result in the alteration or removal of hearth stones making them no longer fit for purpose. Fires lit in inappropriate fire places can lead to smouldering fires developing around hearths and in joists below the fireplace

Question 12

Fires involving chimneys & ducting

What are the hazards from insulating materials ?

Answer 12

Chimneys and ducting use various insulating materials for sound proofing and heat protection. This material may including fibrous lagging or loft insulation, asbestos and intumescent paints. During fire conditions, or when broken up, powder or dust may form a respiratory hazard.

Question 13

Fires involving chimneys & ducting

What are the hazards from electrical extraction systems or filters ?

Answer 13

Electrical supplies to extraction system or filters can be compromised as a result of fire and lead to electrical shock

Question 14

Fires involving chimneys & ducting

What are the potential hazards that could be created by ‘Damage control’ ?

Answer 14

Application of water to chimneys or ducting to extinguish a fire can lead to significant damage following water run off contaminated by soot and grease.

Question 15

Fires involving chimneys & ducting

What are the potential hazards that could occur as a result of unauthorised building works ?

Answer 15

Ducting fitted during refurbishment can create unstopped holes and gaps through compartment and fire resisting walls, leading to rapid and more extensive spread of fire and smoke

Question 16

Fires involving chimneys & ducting

What are the ‘On arrival’ tactics for fires involving chimneys & ducting ?

Answer 16

• The incident commander (IC) should ensure appliances are sited in a safe location away from any possible collapse and falling debris. The positioning of appliances should also allow access and egress for aerial appliances and specialist vehicles.
• The IC should locate the responsible person for the premises, gather all relevant information and where possible obtain plans of ducting routes or chimneys.
• The rapid and accurate location and identification of ducting routes will have a significant impact on the successful resolution of the incident.

Question 17

Fires involving chimneys & ducting

What are ‘Fire dampers’ ?

Answer 17

Fire dampers are automatic fire prevention systems used in heating, ventilation, and air conditioning ducts designed to prevent the spread of fire inside the ductwork through fire-resistant walls and floors. These systems usually consist of a shutter system with a thermal element which closes during a fire, isolating the fire

Question 18

Fires involving chimneys & ducting

What is the ‘Operational procedure’ for a fire in ducting ?

Answer 18

• Consider the need for requesting aerial appliances
• Consider the need for a ‘Fire safety officer’
• If fibrous insulation needs to be removed, seek advice from a HMEPO
• Inspect the full lenght of the ducting using a ‘TIC’ as part of tactical plan
• Establish safety officers at ground & roof level as appropriate
• The correct weight of attack & PPE in place before opening/creating inspection/access panels
• Isolate Electricity and gas as appropriate
• Where possible, attack fire from base

Question 19

Fires involving chimneys & ducting

How could an aerial appliance be used in a incident with fires involving chimneys & ducting ?

Answer 19

The early use of aerial appliances could be used to gain safe access to chimneys or roof top ducting outlets to provide either a covering jet or an observation platform

Question 20

Fires involving chimneys & ducting

How could a ‘Fire safety’ officer provide assistance ?

Answer 20

The IC must make every effort to obtain building plans to assist with tracking the route of ducting and should consider requesting a fire safety officer to assist with interpretation of these plans.

Question 21

Fires involving chimneys & ducting

Why should an IC consider requesting a HMEPO ?

Answer 21

Before removing fibrous insulation material the IC should identify the material involved and consider seeking advice from a hazardous materials and environmental protection officer (HMEPO). In this circumstance respiratory protective equipment (RPE) must be considered.

Question 22

Fires involving chimneys & ducting

In the majority of cases chimney fires are not dynamic incidents requiring immediate action, With that in mind, what should an IC implement before commencing firefighting ?

Answer 22

ICs should take time to identify the exact location of the fire, formulate a definitive plan to extinguish it and implement an appropriate damage control plan before firefighting operations commence.

Question 23

Fires involving chimneys & ducting

What technique should be tried first at a fire in a chimney that is close to the base ?

Answer 23

The application of small quantity of water onto a fire in a hearth or at the base of a chimney will produce steam which can, if the fire is relatively small and close to the base of the chimney, be sufficient to extinguish the fire.

Question 24

Fires involving chimneys & ducting

What equipment should be used to extinguish a fire in the lower part of a chimney if spraying water on to the hearth to create steam does not work ?

Answer 24

The rose nozzle and chimney rods should be used as per the chimney gear

Question 25

Fires involving chimneys & ducting

Where should firefighting be carried out if the fire is in the upper part of the chimney or ducting ?

Answer 25

If the fire is in the upper part of the chimney or ducting then it may then be necessary to attack the fire from the outlet.

Question 26

Fires involving chimneys & ducting

Where the risk assessment indicates issues which prevent the fire from being extinguished, the IC may decide to allow the fire to burn out, What control measures should an IC put in place ?

Answer 26

In these circumstances exposed risks must be covered with appropriate extinguishing media, and particular attention should be made to identify any possible fire spread utilising thermal image cameras.

Question 27

Fires involving chimneys & ducting

What piece of equipment is essential for checking on the location and for fire spread ?

Answer 27

Question 28

Fires involving chimneys & ducting

Before leaving the incident the IC should hand over the premises to the responsible person. What information should be handed over ?

Answer 28

• Reporting damaged or defective site equipment.
• Breaches in fire stopping between compartments.
• Reporting failures in fire safety equipment that may compromise the building’s safety.
• Highlight areas of danger and the status of building utilities.
• If the building is under construction, it may be necessary to report issues to the HSE.