Flow Path?
FIRE ALWAYS MOVE FROM HIGH TO LOW PRESSURE
movement of heat and smoke from the HIGHER PRESSURE within the fire area towards the LOWER pressure areas accessible via doors, window openings and roof structures….may be several flow paths within a
structure
-this can be BIDIRECTIONAL OR UNIDIRECTIONAL depending on LOCATION of MAIN BODY OF FIRE IN RELATION TO VENTILATION OPENING AND NEUTRAL PLANE
Modern Content Fire?
fires that involve HYDROCARBON AND SYNTHETIC based contents such as foam rubber, nylon , rayon and polypropylene…HIGH HEAT RELEAS RATE
When Ventilation is controlled and communicated by LCO INSIDE FIRE AREA TO BE VENTED…
dramatically increase survivability of trapped civilians and increases the safety of our members and improves overall operation
Moder Content Fires…
- hydrocarbons and synthetics-rapidly consume oxygen and burn at greater rate
- fires quickly become ventilation limited due to HIGH FUEL LOAD
- enter early decay stage due to limited oxygen, producing heavy smoke and varying heat conditions
- will remain in decay stage as long as it remains ventilation limited
Traditional Fire..?
Incipient
growth
fully developed
decay
Moder Content fires?
- Incipient
- rapid growth-consumes oxygen quickly
- early decay-oxygen limited–will remain in decay as long as no oxygen is introduced to fire area
- rapid 2nd growth- oxygen added-increases heat release rate—more heat/more smoke-FLASHOVER MAY occur here….
- Transitioned to Fully developed
- 2nd decay- fuel load depleted or fire extinguised
COORDINATED ATTACK FIRE BEHAVIOR CURVE:
- fire will behave in same way up until the EARL DECAY stage
- if no OXYGEN is admitted to heated atmosphere, FIRE WILL stay in an ELONGATED DECAY stage..elongated decay stage where fire is kept ventilation limited is the stage where FF’S can operate effectively and extinguish the fire by DENYING the fire additional oxygen, thereby limiting fire growth and smoke production…This stage is maintained by FF’s by coordinating ventilation with the application of water on the fire
Factors affecting ventilation tactics…
- energy efficient construction/windows/insulation
- PPE better- difficult to detect deteriorating conditions
- TIC is important
- hydraulic forcible entry tools-quicker access- INCREASED time between LADDER ACCESS and ENGINE CHARGE HOSELINE
Until________it is critical to control flow path of fire?
CHARGED HOSE LINE
Ventilation profile?
appearance of the fire buildings ventilation points showing the flow paths of heat and smoke out of the structure as well as air movement into the structure , this is an EVALUATION OF FIRE BEHAVIOR
examples of ventilation profile indicators :
- changes (increase or decrease) in VOLUME, PRESSURE, VELOCITY of smoke/fire venting
- smoke under pressure from opening covering to flame
** changes of ventilation profile indicators must be communicated via HT to LADDER COMPANY OFFICER operating inside fire area and INCIDENT COMMANDER
While in decay stage, fire may no longer have enough pressure to push smoke from the fire area or building, assumption that the absence of smoke pushing from a building is a positive sign, is NOT ACCURATE
MODERN CONTENT FIRES require control of ventilation tactics to prevent a ventilation induced flashover
- FLAMES VENTING out a window are indication of -high heat and smoke conditions–venting fire should NOT be considered favorable condition, still need to coordinate vent tactics
- more flames fill open window, more members can expect sever interior conditions
modern content-develop faster-high heat-more venting flames fill a window..MORE SEVER CONDITIONS
All HORIZONTAL Ventilation tactics- whether venting for extinguishment or ventilation for search, require communication and coordination with LCO…
INSIDE FIRE AREA TO BE VENTED
Horizontal ventilation tactics include controlling door and window openings until
CHARGED HOSELINE IS ADVANCING WITHIN THE FIRE AREA and extinguishing the fire
- reduce temperatures in fire area
- limit flow path of additional oxygen
- improving conditions
- maintain tenability in fire area
- limit fire growth
If officer encounters HIGH HEAT/SMOKE CONDITIONS WITHOUT A charged hose line …
he CAN direct members to IMMEDIATELY EXIT(not a must) or ISOLATE AREa, limit additional .ventilation— horizontal vent prior to extinguishment WILL NOT cool or relieve these conditions, but will allow fire to grow
CHARGED LINE IS NEEDED
FLOOR ABOVE:
if the LADDER company officer determines the fire has NOT communicated to the floor above, LIMITED ventilation is justifiable if if facilitates search operations,
-so officer can ventilate to facilitate search if fire has NOT COMMUNICATED to floor above
Initial Vertical Ventilation must be controlled, communicated and coordinated by LCO operating inside the fire area to be vented
LCO should establish door control of fire area and perform a vent profile at the entry point (pay attention to AIR being pulled in)
-COMMUNICATE WITH ROOF when vertical vent is NOT to be taken , or delayed (unable to gain door control and/or uncontrolled fire in the public hall or stairwell)
Roof FF can perform INITIAL VERTICAL VENTILATION upon reaching the roof.
LCO will advise roof when vertical vent should be withheld or delayed
- initial vertical vent-skylights, bulkheads, scuttles over stairwells/hallways
- after initial vertical vent is completed, communicate to OFFICER
IF INITIAL VERTICAL VENT is withheld, ROOF FF CAN FORCE BULKHEAD DOOR AND PROBE FOR VICTIMS, THEN CONTROL
MEMBER on Exterior waiting to perform the Horizontal Ventilation for Extinguishment OF IMMEDIATE FIRE AREA shall listen for these transmission?
- “start water”
- “we are knocking down visible fire”
member must PREPARE to vent for extinguishment
member must get PERMISSION
Fire progresses past the INCIPIENT STAGE, fire is IDLH…NO MEMBER SHALL ENTER, LEAVE,OPERATE in an IDLH UNLESS MEMBER TEAMS UP WITH AT LEAST ONE OTHER MEMBER AND …
remains within VISUAL OR VOICE CONTACT with that member…each member of search team shall know the company identity and assigned position of other members…HT does NOT replace Visual/Voice contact….AT LEAST ONE of the members must be able to contact a HT equipped member of the safety team outside the IDLH ATMOSPHERE
Only exception….KNOWN LIFE HAZARD
Still must notify LADDER COMPANY OFFICER AND RECEIVE APPROVAL
- seen
- heard
- credible source or person at scene
LCO may disapprove rescue and may have quicker access from interior
Prior to Venting the window, for search, member must…?
- assess area for tenability and risk
- decision made and APPROVAL granted-CLEAR WINDOW and be aware of new flow path
- REASSESS conditions….if these conditions prevent access, notify LCO
- conditions tenable..reach in and probe immediate area for victims
- enter, ISOLATE area by closing door and then search
- victim found before isolating, MEMBER SHOULD ISOLATE FIRST AND THEN RESCUE
auto exposure..
extension of fire via the exterior of a building from a fire originating in the SAME BUILDING
decay stage..
–stage of fire development within a structure characterized by either a DECREASE in the fuel load OR AVAILABLE OXYGEN (ventilation limited)
Flashover..
feedback from fire gases in EXCESS of 1100 degrees reach auto ignition temp more or less simultaneously
BI directional flow path..
flow path where gases from fire area (high pressure) flow TOWARDS ventilation point (LOW pressure) and an entrainment of fresh air in the opposite direction back to the seat of the fire.
NEUTRAL PANE
boundary layer in a structure fire where below it, air will be drawn into the structure, and above it, combustion gases will be exhausted …can be indication of stage of fire and WILL DROP down to floor as fire grows in intensity
