Upload
marquez-chatman
View
217
Download
0
Tags:
Embed Size (px)
Citation preview
Chimney Fires Chimney Fires
Construction, Challenges Fire Control Best Practices
Objectives
• Review different types of chimney construction
• Identifying lines vs. unlined flues
• Understand fire spread characteristics of most common chimney types
• Effective fire control practices
Chimney Construction
• The chimney method of smoke removal has been around for centuries
• Early man discovered the benefits of vertical draft methods in removing smoke from caves, huts, etc.
Chimney Construction (cont.)
• Various means to construct vertical drafts (chimneys) used:– Stone
– Mud/sticks
– Hollow logs
– Bricks
– Metal (modern)
Attachment Methods
• Interlock wall stones with chimney stone
• Free-standing
• Wall logs interlocked in stone or brick
• Metal ties to wall framing (20th century)
• Metal bracing within wood framework (modern zero-clearance chimney piping)
Lined Flue
• Inside of chimney construction contains flue “pipe” or “lining” that minimizes openings, joints, or crevices along vertical path of heat, smoke, embers
Metal Chimney Liner
Tile Chimney Liner
Liner Characteristics…
• Each type of liner has it’s benefits and drawbacks…– Metal is expensive, but crack resistant and
often installed in one piece top-to-bottom.– Most common sizes are 6- and 8- inch– Easy connection to wood/coal stoves– Can be routed through some twists and turns– Can retrofit old, unlined flues
Liner Characteristics (cont.)
• Tile, or terra cotta, offer wider passages than metal and are less expensive than metal
• Not used in retrofits or relining of existing flues
• Susceptible to temperature extremes and settling of foundations, causing cracking
• May consist of several joints
Zero-Clearance or Prefabricated Metal Chimney Flues
• Developed nearly 25 years ago to service the growing alternative heating market
• Consist of multiple layers of stainless steel separated by fire-retardant insulation
Unlined Flues
• Found in many homes built prior to 1930
• May be of stone or brick construction
Unlined Flues (cont.)
Fire Spread Characteristics
Tile/Terra Cotta Liners
• Cracks appearing over time and temperature extremes provide openings for hot ash/embers to exit the flue and contact adjacent combustible framing members
• May also provide path into void spaces, carrying sparks into area containing combustibles (attic, behind knee wall)
Terra Cotta/Tile Liner (cont.)
• Subject to degradation from rain, ice, snow
• Mechanical damage from improper cleaning, previous fires
• Damage introduced from exterior forces (wind, trees)
Metal Chimney Liners
• May warp from extremes in temperature (burning stove too hot)
• Improper attachment of flue sections
Metal Flues (cont.)
• Joints may be open, allowing sparks and embers to escape into void and combustible spaces adjacent to chimney, permitting fire spread and slow detection of same.
• Stainless steel tubular liners are used in older unlined retrofitting, often resulting in turns and twists permitting build up of creosote and animal nests.
Creosote Buildup
• Creosote is a byproduct of INCOMPLETE combustion.
• Adheres to tile, unlined, flexible metal, and joints in flue liners
Creosote (cont.)
• Relatively cool temperatures in upper portion of flue condense products of combustion into potential “time bombs” on liners.
• Can be minimized by burning proper fuels (seasoned wood) at proper temperature recommended by stove/fireplace manufacturer
Animal Nest in Chimney Flue
Retrofitting Unlined Flues
• It is common to find older, unlined chimneys outfitted with new style flexible, stainless steel tubular liners
• Often connect to wood stove or insert
• May be placed in unlined flue surrounded by fire-resistant material such as a vermiculite/gypsum mix
Prefabricated Metal Chimneys
• Have Class “A” fire rating and may be used inside of wooden box framing according to building codes and Underwriter’s Laboratories test results
• Lock together in a twisting motion
• Are NOT fire PROOF!!!
Identifying Fire Presence and Control Options
Caller Complaints
• Hear persistent “roaring” sound from upper flue area
• Smoke from chimney when no active fire in fireplace/ stove
• Haze/smoke odor in upper floors of house and/or attic
• Walls adjacent to chimney hot to touch
Fire Control Tactics
• Thermal Imager A MUST!!!!
• Get personnel ABOVE and BELOW fireplace/stove-check walls, floor space adjacent to flue--attic
• Check flue clean out (if present)
• Roof crew to check openings at top
Tactics (cont.)
• Remove active fire from firebox
• Closely monitor flue for active flames
• Consider use of dry chemical extinguisher or “chimney bombs” (dry chem in plastic baggies dropped from top of chimney)
• Pressurized water extinguisher and/or preconnect should be LAST RESORT
• Once fire controlled, occupant must be directed to have licensed chimney sweep clean and inspect chimney PRIOR to ANY additional usage.
• Officer should document this on NFIRS report.
Points to Consider…
• Successful control of chimney fires requires time and patience
• Continual monitoring of all adjacent combustible areas required during operations
• Older, unlined flues often contain structural framing members tying chimney to house
Other Important Considerations…
• EARLY laddering of roof
• Use of chimney chains to clear flaming creosote (if available on scene)
• Aggressive investigation of adjacent void spaces
• Identification of lined vs. unlined flue
Summary
• Firefighters should be familiar with the various chimney types
• Understand particular hazards of each type of flue
• Recognize signs of active fire situations in flue and execute proper control methods
Summary (cont.)
• Make every attempt to control fire while minimizing damage to chimney/flue structure
• Ensure safe operations when working in poor lighting and on wet/icy or steep roof pitches
• Have a safe, happy, injury- and fire-safe holiday season!!!!!