Posts Tagged ‘practical fire dynamics’

Door Control Doctrine

As discussed in my last post, doctrine is a guide to action rather than a set of rigid rules. Clear and effective doctrine provides a common frame of reference, helps standardize operations, and improves readiness by establishing a common approach to tactics and tasks. Doctrine should link theory, history, experimentation, and practice to foster initiative and creative thinking.

One way to frame the discussion necessary to develop doctrine that is applicable to a range of circumstances, is to use a series of scenarios presenting different conditions and examine what is similar and what is different. Ideally, firefighters will work together to integrate this theoretical discussion with their experience to develop sound doctrine based on their own context (e.g., staffing, building and occupancy types).

Fireground Scenarios

Important! Not all of the tactics presented in the questions are appropriate and others may be appropriate in one context, but not necessarily in another. For example, a lightly staffed engine may not have the option of offensive operations until the arrival of additional resources (barring a known imminent life threat), where a company with greater staffing may have greater strategic and tactical flexibility. These questions focus on the impact of strategic (offensive or defensive) tactical options on fire dynamics.

Scenario 1: The first arriving company arrives to find a small volume of smoke showing from around windows and doors and from the eaves on Side Alpha with low velocity, no air inlet is obvious. Performing a 360^o reconnaissance, the officer observes similar smoke and air track indicators on other sides of the building and that all doors and windows are closed. Several windows on Side Alpha (Alpha Bravo Corner) are darkened with condensed pyrolysis products and the home appears to have smoke throughout (smoke logged).

How do you think the fire will develop between arrival and initiation of offensive fire attack (assuming that adequate resources are on-scene for offensive operations) assuming no change in ventilation prior to fire attack.

The fire is likely in a ventilation controlled, decay stage. If the ventilation profile does not change prior to entry (e.g., doors are kept closed, windows remain intact), the heat release rate (HRR) from the fire will continue to decline and temperatures within the building will drop (but may still be fairly high when entry is made).

How would opening the front door prior to having a charged line at the doorway on Side Alpha impact fire development?

Increased ventilation will result in a significant and potentially rapid increase in HRR. The proximity of the door to the fire compartment and temperature in the fire compartment at the time that ventilation is increased will have a direct impact on the speed with which the fire returns to the growth stage (but still remaining ventilation controlled). The closer the air inlet to the fire and the higher the temperature, the more rapidly the fire will return to the growth stage.

How would horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development if performed as soon as the hoseline is deployed to the (still closed) doorway on Side Alpha?

As noted in the answer to question 2, increased ventilation will result in an increase in HRR. As windows in the fire compartment are in closer proximity to the fire, taking the windows potentially will result in a more rapid return to the growth (but still ventilation controlled) stage. It is also important to consider that a window cannot be unbroken; selecting this ventilation option does not provide an option for changing you mind if you do not like the result.

What would be the impact on fire behavior if the engine company advanced the first hoseline to the windows; took the glass and applied water to the burning fuel inside the fire compartment prior to making entry through the door? How might this change if offensive fire attack was delayed (e.g., insufficient staffing for offensive operations)?

This is an interesting question! Research by UL, NIST, and FDNY has shown the positive impact of exterior application of water into the fire compartment in reducing heat release rate. However, as noted in the answer to the preceding question, a window cannot be unbroken. If this is simply a contents fire in the compartment where the window is broken and water is applied, the result is likely to be favorable with a temporary reduction in HRR due water applied on burning fuel. However, if the fire extended to other areas of the building which shielded from direct attack at this point of application, effectiveness of exterior application from this single location is likely to be limited.

How would opening the front door and horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development if performed as soon as the hoseline is deployed to the doorway on Side Alpha?

Advice on coordination of tactical ventilation and fire attack has typically stated, don’t vent until a charged hoseline is in place. This is good advice, but requires a bit of clarification.

“As soon as the hoseline is deployed to the doorway” may simply mean that a dry line has been stretched and firefighters are donning their self-contained breathing apparatus (SCBA) facepieces while waiting for water. The fire will begin transition back to the growth stage as soon as tactical ventilation is performed. Depending on the time required for the firefighters to mask up, the line to be charged, air bled off, pattern checked, and the charged line advanced to the fire compartment(s), the HRR may increase significantly and conditions are likely to be quite a bit worse than if the door and window had remained closed until the hoseline was in place to begin offensive fire attack from the interior.

If tactical ventilation is performed after the line is charged and firefighters are ready to immediately make entry and quickly advance to the fire compartment, it is likely that the effect of increased ventilation will be positive. There may be some increase in HRR, but it is likely to be minimal due to the short distance and simple stretch from the front door to the fire compartment(s). Once direct attack has begun to control the fire, the increased ventilation will improve conditions inside the building.

Assuming that sufficient resources are on-scene to permit an offensive attack, when should the entry point be opened? Assuming that the door is unlocked, how should the fire attack crew approach this task?

Tactical size-up is critical for the crew assigned to offensive fire attack. This includes assessment of B-SAHF (Building, Smoke, Air Track, Heat, and Flame) indicators, forcible entry requirements, and assessment of fire attack requirements (e.g., flow rate, length of line, and complexity of the stretch).

The door should remain closed until the crew on the hoseline is ready to make entry; hoseline charged, air bled off, nozzle function and pattern checked, SCBA facepeices on, on-air. Check to see if the door is unlocked, but control the door (closed) and check conditions inside (visible fire, level of the hot upper layer, presence of victims inside the doorway) by opening the door slightly. The firefighter on the nozzle should do this check while the tools firefighter opens and controls the door. If hot smoke or flames are evident, the nozzle firefighter should cool the upper layer with one or more pulses of water fog (depending on conditions). The door should be closed while the crew assesses the risk of entry (e.g., floor is intact and fire conditions will permit entry from this location). If OK for entry; the crew can open the door and advance the line inside, while cooling the upper layer as necessary.

See Nozzle Techniques & Hose Handling: Part 3 for additional information on door entry procedure.

Once the hoseline is deployed into the building through the door on Side Alpha for offensive fire attack, should the door remain fully open or closed to the greatest extent possible? Why?

Ideally, the door will be closed after the hoseline is advanced through the doorway to limit the air supplied to the fire. How this is accomplished will depend on staffing. The door may be controlled by the fire attack crew or it may be controlled by the standby crew (two-out).

As discussed in the prior post Influence of Ventilation in Residential Structures: Tactical Implications Part 2, when the door is open, the clock is ticking! In the ventilation controlled burning regime, increased ventilation results in an increasing HRR as the fire returns to the growth stage. The timeframe for increased HRR is dependent on the proximity of the inlet to the fire, configuration of the building, and temperature in the fire area (higher temperature results in faster increase in HRR). Closing the door (even partially) slows the increase in HRR. Once the attack line begins direct attack, the door can be opened as part of planned, systematic, and coordinated tactical ventilation.

Assuming that this is a contents fire and horizontal ventilation will be appropriate, when and where should it be performed (describe the flow path from inlet to exhaust)?

As with most questions, the answer here is “it depends”. There are a few missing bits of information that are important to horizontal tactical ventilation. Wind direction and the location of potential openings. To keep things simple, assume that there is no wind and that the only potential openings in the fire compartment are two windows on Side Alpha at the Alpha/Bravo Corner.

Once direct attack has commenced, horizontal tactical ventilation can be performed from Alpha (doorway) to Alpha (windows in the fire compartment). As the top of the door and tops of the windows are likely to be approximately at the same level, there a bi-directional flow path (smoke out at the top and air in at the bottom) is likely to develop. However, the bottom of the door is lower than the windows which will provide increased air movement from the door to the fire compartment.

In discussing this question (and the entire topic of door control for that matter), some firefighters will undoubtedly raise the question of positive pressure attack (PPA) or positive pressure ventilation (PPV). These tactics may provide an effective approach in this scenario, but developing comprehensive tactical ventilation doctrine requires examination of all of the options to control both smoke and air movement, so we are starting with a look at anti-ventilation and tactical ventilation using natural means.

Scenario 2: The first arriving company arrives to find smoke showing with moderate velocity and a bi-directional air track (smoke out the top and air in the bottom) from an open door on Side Alpha. A moderate volume of smoke is also pushing from around windows and from the eaves on Side Alpha. Several windows on Side Alpha (Alpha Bravo Corner) are darkened with condensed pyrolysis products and a glow is visible inside in the room behind these windows. Performing a 360^o reconnaissance, the officer observes similar smoke and air track indicators on other sides of the building and that all doors and windows with the exception of the door on Side Alpha are closed. Returning to Side Alpha, the officer observes that the velocity of smoke from the open door has increased and flames at the interface between the smoke and air as it exits the doorway. The home appears to have smoke throughout (smoke logged).

How do you think the fire will develop between arrival and initiation of offensive fire attack (assuming that adequate resources are on-scene for offensive operations) assuming no change in ventilation prior to fire attack.

The fire is in a ventilation controlled burning regime (indicators include the limited ventilation provided by the single opening at the front door and flames at the interface between the smoke and air at the door). The open door will likely provide sufficient ventilation for the fire to continue its growth and extension from the compartment of origin along the flowpath to the front door.

How would the officer closing the front door prior to having a charged line at the doorway on Side Alpha (e.g., when performing the 360) impact fire development?

Based on the reported observations during 360^o reconnaissance, the only significant ventilation opening is the front door. The bi-directional air track indicates that this opening is serving as both an inlet and outlet. Closing the door will reduce the air supply to the fire and will reduce the HRR and slow worsening conditions outside the fire compartment. Ideally this would be done prior to starting the 360^o reconnaissance.

Assuming that sufficient resources are on-scene to permit an offensive attack and the door was closed during the 360, when should the entry point be opened? How should this task be approached?

As in Scenario 1, the door should be opened only when the crew on the hoseline is ready to make entry; hoseline charged, air bled off, nozzle function and pattern checked, SCBA facepeices on, on-air. The same door entry procedure described in Scenario 1 should be used as if the door had been closed on arrival.

How would horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development is performed as soon as the hoseline is deployed to the open doorway on Side Alpha?

The outcome of tactical ventilation of the fire compartment will depend on sequence and timing. If the door remained open during initial size-up and while the line was being stretched, he fire would have continued to grow (limited by ventilation provided by the doorway and interior configuration of the building). Additional ventilation in this case would result in a rapid increase in HRR. If the door had been closed during the 360, the increase in HRR on ventilation of the windows would likely be somewhat slower as the HRR and temperature in the fire compartment would have dropped once the door was closed. In either case, HRR will increase while the charged line is being stretched from the entry point to the fire compartment. This is not necessarily a problem if the stretch is quick and the flow rate of the hoseline is adequate. It is essential that the crews stretching the line and performing ventilation understand the influence of their actions on fire behavior and are not surprised at the result.

Once the hoseline is deployed into the building through the door on Side Alpha for offensive fire attack, should the door remain fully open or closed to the greatest extent possible? Why?

As noted in Scenario 1, closing the door to the greatest extent possible after the line is inside will slow fire development until the hoseline is in place to begin a direct attack.

Assuming that this is a contents fire and horizontal ventilation will be appropriate, when and where should it be performed (describe the flow path from inlet to exhaust)?

The same basic approach would be taken as in Scenario 1. Once direct attack has commenced, horizontal tactical ventilation can be performed from Alpha (doorway) to Alpha (windows in the fire compartment).

Scenario 3: The first arriving company arrives to find smoke showing with moderate velocity and a bi-directional air track (smoke out the top and air in the bottom) from an open door on Side Alpha. A moderate volume of smoke is also pushing from around windows and from the eaves on Side Alpha. Flames are visible from several windows on Side Alpha (Alpha Bravo Corner) with a bi-directional air track (flames from the upper ¾ of the window with air entering the lower ¼). Performing a 360^o reconnaissance, the officer observes similar smoke and air track indicators on other sides of the building and that all doors and windows with the exception of the two windows and door on Side Alpha are closed. Returning to Side Alpha, the officer observes that the velocity of smoke from the open door has increased and flames at the interface between the smoke and air as it exits the doorway. Flames from the windows on Side Alpha are similar to when first observed. The home appears to have smoke throughout (smoke logged).

How do you think the fire will develop between arrival and initiation of offensive fire attack (assuming that adequate resources are on-scene for offensive operations) assuming no change in ventilation prior to fire attack.

The fire is likely in a ventilation controlled burning regime (indicators include the limited ventilation provided by the openings at the front door and windows. Existing ventilation will likely be sufficient for the fire to continue its growth and extension from the compartment of origin along the flowpath to the front door. As there are multiple ventilation openings (more cross sectional area), HRR is greater and as a result fire development and spread will be much more rapid than in Scenario 2.

How would the officer closing the front door prior to having a charged line at the doorway on Side Alpha (e.g., when performing the 360) impact fire development?

As the windows in the fire compartment have failed and are serving as ventilation openings (in addition to the front door), the fire will likely remain in a ventilation controlled growth stage even if the door is closed. However, closing the door will still reduce the air supply to the fire and will slow fire growth. In addition, elimination of the flow path between the fire compartment and front door will reduce heat transfer along this flow path.

Assuming that sufficient resources are on-scene to permit an offensive attack and the door was closed during the 360, when should the entry point be opened? How should this task be approached?

As in Scenarios 1 and 2, the door should be opened only when the crew on the hoseline is ready to make entry; hoseline charged, air bled off, nozzle function and pattern checked, SCBA facepeices on, on-air. The same door entry procedure described in the prior scenarios should be used.

How would horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development if performed as soon as the hoseline is deployed to the open doorway on Side Alpha?

As the windows in the fire compartment have already failed, some ventilation of the fire compartment has already occurred. In that the fire is ventilation controlled, any additional ventilation will significantly increase HRR. With a ventilation controlled growth stage fire and high temperature in the fire compartment, the HRR will increase rapidly.

Once the hoseline is deployed into the building through the door on Side Alpha for offensive fire attack, should the door remain fully open or closed to the greatest extent possible? Why?

As in the previous two scenarios, the door should be closed to as great an extent possible after the hoseline is advanced inside the building. This will limit air to the fire, slow fire development, an reduce the flow path between the fire and the front door.

Assuming that this is a contents fire and horizontal ventilation will be appropriate, when and where should it be performed (describe the flow path from inlet to exhaust)?

As the windows in the fire compartment have already failed, they will continue to provide ventilation. Once a direct attack has been initiated, the front door may be opened to increase air flow and the efficiency of the horizontal ventilation from Side Alpha to Side Alpha.

As noted in the previous post, these questions were all based on a similar fire (different development based on the ventilation profile at the time of the first company’s arrival) in the same, simple building, a one story, wood frame dwelling. It is important to examine other levels of involvement and ventilation profiles in this building as well as other types of buildings and fire conditions with similar questions. Also give some thought to the impact of door control when using vertical ventilation in coordination with fire attack.

Additional Examples

The following video of pre-arrival conditions and initial fireground operations provides an additional opportunity to consider the impact of ventilation and the importance of door control.

Video 1: In the first video, the door is closed when the fire department arrives, but the fire has self-vented through a window on Side Delta.

How might effective door control have influenced fire development and the safety of companies operating at this incident?

Video 2: In this video, the front door is open when the fire department arrives and it appears that the fire may have self-vented on Side Charlie.

How might effective door control have influenced fire development and the safety of companies operating at this incident?

Video 3: In the last video, the front door is partially open and existing ventilation includes a window on Side Alpha and one or more openings on Side Charlie.

How might effective door control have influenced fire development and the safety of companies operating at this incident?

My next post will come back to the final set of questions regarding door control doctrine posed in Close the Door! Where You Born in a Barn?

Coming and going as a little kid, I frequently would forget to close the door to the house and my mother would say; close the door! Were you born in a barn? What does this have to do with firefighting operations? As it turns out, it has significant impact!

Research conducted by Underwriters Laboratories (UL), National Institute of Standards and Technology (NIST), and the Fire Department of the City of New York (FDNY) points to the importance of close coordination of tactical ventilation (including opening a door to gain access) and fire attack. While doors are not ordinarily considered a firefighting tool, this post examines door control as an essential element in firefighting operations.

The Fire Environment-A Quick Review

Modern homes have a high fire load (both in mass and heat of combustion of common building contents), are better insulated and more energy efficient, and are larger and have large open, undivided living spaces.

These conditions often result in rapid fire development and transition from a growth stage, fuel controlled burning regime to decay stage, ventilation controlled burning regime prior to the arrival of the fire department. Increased ventilation (without concurrent fire control) will result in increased heat release rate, returning the fire to the growth stage and rapid transition through flashover to a fully developed stage of fire development.

A number of factors influence the speed with which heat release rate accelerates when the air supplied to a ventilation controlled fire increases. These include building and compartment size and geometry, thermal conditions, and size and location of the ventilation openings.

• In general, fires in smaller compartments will react more quickly, but compartmentation and complex geometry will slow air movement from the inlet to the fire, and resulting increase in HRR.
• Introduction of air close to the fire will influence HRR more quickly than air introduced at a distance.
• Exhaust openings that are above the fire (horizontal or vertical) will increase HRR more quickly and to a greater extent than those at the same level (but may be more effective in improving conditions when fire control is established)
• Larger openings (or multiple smaller openings) will increase HRR to a greater extent and more quickly than smaller (or fewer) openings.

Conditions on Arrival

A critical element of size-up is identification of the current ventilation profile of the building. Remember that ventilation (exchange of the atmosphere inside the building and that outside the building) is always going on to one extent or another. Assessment of the ventilation profile is based on the Building, Smoke and Air Track elements of B-SAHF (Building, Smoke, Air Track, Heat, and Flame) Fire Behavior Indicators (FBI). Starting with Building factors, consider the nature of current ventilation openings:

• No significant ventilation openings (normal building leakage only)
• One or more doors may be open
• One or more windows may be open
• Some combination of door(s) and window(s) may be open

In addition to the ventilation openings, it is important to consider if they are exhaust openings, inlets, both exhaust and inlet, and what is visible; flames or smoke:

• Nothing showing (remember that this means nothing, the fire may be ventilation controlled and in the decay stage, but interior temperatures may be above 425^o C (800^o F) even when little or nothing is showing from the exterior.
• Smoke showing from ventilation openings (consider the direction of the air track at each opening, in, out, bi-directional, or pulsing)
• Smoke and flames showing from ventilation openings (as with smoke, consider the direction of the air track)

Structural Firefighting is Simple

OK this is a bit of an overstatement (actually more than a bit). Generally, there are only two things that firefighters can do to influence fire behavior; change the ventilation or absorb the energy being released by the fire. Read each of the following three scenarios and consider the questions posed. While examining door control, this anti-ventilation tactic is not used alone so there are a few questions that address fire control tactics (which will be the subject of a subsequent post).

Scenario 1: The first arriving company arrives to find a small volume of smoke showing from around windows and doors and from the eaves on Side Alpha with low velocity, no air inlet is obvious. Performing a 360^o reconnaissance, the officer observes similar smoke and air track indicators on other sides of the building and that all doors and windows are closed. Several windows on Side Alpha (Alpha Bravo Corner) are darkened with condensed pyrolysis products and the home appears to have smoke throughout (smoke logged).

1. How do you think the fire will develop between arrival and initiation of offensive fire attack (assuming that adequate resources are on-scene for offensive operations) assuming no change in ventilation prior to fire attack.
2. How would opening the front door prior to having a charged line at the doorway on Side Alpha impact fire development?
3. How would horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development if performed as soon as the hoseline is deployed to the (still closed) doorway on Side Alpha?
4. What would be the impact on fire behavior if the engine company advanced the first hoseline to the windows; took the glass and applied water to the burning fuel inside the fire compartment prior to making entry through the door? How might this change if offensive fire attack was delayed (e.g., insufficient staffing for offensive operations)?
5. How would opening the front door and horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development if performed as soon as the hoseline is deployed to the doorway on Side Alpha?
6. Assuming that sufficient resources are on-scene to permit an offensive attack, when should the entry point be opened? Assuming that the door is unlocked, how should this task be approached?
7. Once the hoseline is deployed into the building through the door on Side Alpha for offensive fire attack, should the door remain fully open or closed to the greatest extent possible? Why?
8. Assuming that this is a contents fire and horizontal ventilation will be appropriate, when and where should it be performed (describe the flow path from inlet to exhaust)?

Scenario 2: The first arriving company arrives to find smoke showing with moderate velocity and a bi-directional air track (smoke out the top and air in the bottom) from an open door on Side Alpha. A moderate volume of smoke is also pushing from around windows and from the eaves on Side Alpha. Several windows on Side Alpha (Alpha Bravo Corner) are darkened with condensed pyrolysis products and a glow is visible inside in the room behind these windows. Performing a 360^o reconnaissance, the officer observes similar smoke and air track indicators on other sides of the building and that all doors and windows with the exception of the door on Side Alpha are closed. Returning to Side Alpha, the officer observes that the velocity of smoke from the open door has increased and flames at the interface between the smoke and air as it exits the doorway. The home appears to have smoke throughout (smoke logged).

1. How do you think the fire will develop between arrival and initiation of offensive fire attack (assuming that adequate resources are on-scene for offensive operations) assuming no change in ventilation prior to fire attack.
2. How would the officer closing the front door prior to having a charged line at the doorway on Side Alpha (e.g., when performing the 360) impact fire development?
3. Assuming that sufficient resources are on-scene to permit an offensive attack and the door was closed during the 360, when should the entry point be opened? How should this task be approached?
4. How would horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development if performed as soon as the hoseline is deployed to the open doorway on Side Alpha?
5. Once the hoseline is deployed into the building through the door on Side Alpha for offensive fire attack, should the door remain fully open or closed to the greatest extent possible? Why?
6. Assuming that this is a contents fire and horizontal ventilation will be appropriate, when and where should it be performed (describe the flow path from inlet to exhaust)?

Scenario 3: The first arriving company arrives to find smoke showing with moderate velocity and a bi-directional air track (smoke out the top and air in the bottom) from an open door on Side Alpha. A moderate volume of smoke is also pushing from around windows and from the eaves on Side Alpha. Flames are visible from several windows on Side Alpha (Alpha Bravo Corner) with a bi-directional air track (flames from the upper ¾ of the window with air entering the lower ¼). Performing a 360^o reconnaissance, the officer observes similar smoke and air track indicators on other sides of the building and that all doors and windows with the exception of the two windows and door on Side Alpha are closed. Returning to Side Alpha, the officer observes that the velocity of smoke from the open door has increased and flames at the interface between the smoke and air as it exits the doorway. Flames from the windows on Side Alpha are similar to when first observed. The home appears to have smoke throughout (smoke logged).

1. How do you think the fire will develop between arrival and initiation of offensive fire attack (assuming that adequate resources are on-scene for offensive operations) assuming no change in ventilation prior to fire attack.
2. How would the officer closing the front door prior to having a charged line at the doorway on Side Alpha (e.g., when performing the 360) impact fire development?
3. Assuming that sufficient resources are on-scene to permit an offensive attack and the door was closed during the 360, when should the entry point be opened? How should this task be approached?
4. How would horizontal ventilation of the fire compartment (Alpha/Bravo Corner) impact fire development if performed as soon as the hoseline is deployed to the open doorway on Side Alpha?
5. Once the hoseline is deployed into the building through the door on Side Alpha for offensive fire attack, should the door remain fully open or closed to the greatest extent possible? Why?
6. Assuming that this is a contents fire and horizontal ventilation will be appropriate, when and where should it be performed (describe the flow path from inlet to exhaust)?
7. Assuming that this is a contents fire and horizontal ventilation will be appropriate, when and where should it be performed?

These questions were all based on a similar fire (different development based on the ventilation profile at the time of the first company’s arrival) in the same, simple building, a one story, wood frame dwelling. It is important to examine other levels of involvement and ventilation profiles in this building as well as other types of buildings and fire conditions with similar questions. Also give some thought to the impact of door control when using vertical ventilation in coordination with fire attack.

Door Control Doctrine

Doctrine is a guide to action rather than a set of rigid rules. Clear and effective doctrine provides a common frame of reference, helps standardize operations, and improves readiness by establishing a common approach to tactics and tasks. Doctrine should link theory, history, experimentation, and practice to foster initiative and creative thinking.

Given what we know about the modern fire environment and the influence of both existing and increased ventilation on ventilation controlled fires, what guidance should we provide to firefighters regarding door control? The following questions are posed in the context of a residential occupancy (one or two-family home, garden apartment unit, townhouse, etc.).

1. If the door to the fire occupancy is open when the first company arrives, should it be (immediately) closed by the member performing the 360^o reconnaissance? If so why? If not, why not?
2. If the door should be closed immediately there any circumstances under which it should not? If there are circumstances under which the door should not be closed, what are they and why?
3. If the door is closed on arrival (or you closed the door during the 360o reconnaissance) when and how should it be opened for entry? Think about tactical size-up at the door, forcible entry requirements, and the actual process of opening the door and making entry? How might this differ based on conditions?
4. After making entry should the door be closed to the greatest extent possible (i.e., leaving room for the hoseline to pass)? If so why? If not, why not?
5. If the door should be closed to the greatest extent possible, who will maintain door control and aid in advancement of the line? How might this be accomplished with limited staffing?
6. If you are performing search, should doors to the rooms being searched be closed while searching? If so why? If not, why not? Are there conditions which would influence this decision? If so, what are they?
7. Should the doors to rooms which have been searched be closed after completing the primary search? If so why? If not, why not? Are there conditions which would influence this decision? If so, what are they?
8. How else can doors be used to aid in fire control or the protection of occupants and firefighters? Give this some thought!

Review The Influence of Ventilation in Residential Structures Part 2 for additional information on the influence of ventilation and door control as an  anti-ventilation tactic.

I plan on posting my thoughts on the questions posed in this post next week. However, it would likely make this much more interesting if you post your perspectives (or additional questions) as a comment!

Ed Hartin, MS, EFO, MIFireE, CFO

The importance of the initial Incident Commander conducting 360^o reconnaissance (or quickly obtaining information about conditions on sides of the building that are not visible) has been repeatedly emphasized in National Institute for Occupational Safety and Health (NIOSH) Death in the Line of Duty reports. This is important to assess both building and fire conditions. However, the building was there prior to the alarm of fire. Situational awareness (SA) does not only apply on the fireground, it must begin well before response. In structural firefighting, the built environment (including the building, its contents, and surroundings) are the ground we fight on and in. Situational assessment and size-up must be ongoing.

View from the Street

The Knead & Feed (see photo below), is an excellent restaurant in Coupeville, WA that serves breakfast and lunch. At first glance this building appears to be an older, one-story, wood frame, commercial with the Delta Exposure being a two-story building of similar construction. Given the age of the buildings, it would be reasonable to assume that they are of balloon frame construction. Looking beyond the building you can see Penn Cove, which provides an excellent view from the back of the restaurant.

Reconnaissance on Side C

However, the view in this photo begs the question, what’s on Side C? Access to Side C is via an exterior stairway on Side Bravo. Descending this stairway provides access to another kitchen and dining area in the Basement which is not accessible from the interior of the restaurant on Floor 1. Continuing down the stairway, provides access to a bakery at the Basement 2 level. The stairway then continues down to the beach, providing access to Side C…provided that it is low tide.

Obviously you get a considerably different picture from Side C! However, this is only the beginning of the story.

The Rest of the Story

It may appear that the small, one-story section of building between the Kneed and Feed restaurant and Exposure Delta is part of the exposure due to the color of the building on Side Alpha and the roof line on Side Charlie. However, this assumption would be incorrect as this is the main kitchen for the Kneed and Feed Restaurant.

There is no interior access between Floor 1 and the Basement (in either the Kneed and Feed or Exposure Delta). The Basement and Basement 2 levels of the Kneed and Feed are accessed from the exterior on Side Bravo. The Basement of Exposure Delta (apartment unit) is accessed from the exterior on Side Delta. The second floor of Exposure Delta is accessed from the interior.

Continuing down to the Basement level, the section of the building below the main kitchen contains an unprotected stairwell that is open to the underside of the Basement of Exposure Delta and the void space under the wood sidewalk that runs in front of the restaurant and Exposure Delta. The Basement and Basement 2 levels are interconnected this stairway (non-fire rated doors provide access between the stairway and the Basement and Basement 2. This stairway is framed in at the Basement level, but simply enclosed by wood slats at the Basement 2 level.

Strategic and Tactical Implications

This building presents considerable challenges due to its construction, configuration, attached exposure on Side Delta, and limited access. The following questions provide a starting point for discussion of strategic and tactical implications for this building and its most significant exposure:

1. How might the construction and configuration of this building and exposure impact on the B-SAHF (building, smoke, air track, heat, and flame) indicators presented during a fire? How might this vary based on location (Floor 1, Basement, Basement 2)?
2. How might the open stairwell between the Kneed and Feed and Exposure Delta impact on fire development and spread if the fire originated at one of the basement levels, or within the stairwell itself? How might communication between the stairwell and the wooden sidewalk on Side A impact firefighting operations (note that the sidewalk and void space below extends beyond the access points for Sides Bravo and Delta).
3. How would the open framing under the Basement of Exposure Delta impact on potential for fire spread from the Kneed and Feed to Exposure Delta (particularly if a fire originated on the Basement or Basement 2 level)
4. How would tidal conditions impact on access to Side Charlie for firefighting operations or placement of ladders for rescue or secondary egress from the Kneed and Feed or Exposure Delta (particularly the apartment unit in the Basement of Exposure Delta).
5. What strategies and tactics would provide the safest and most effective approach to confining and extinguishing a fire in each level of this building?
6. Given the significant threat to Exposure Delta should a fire occur in the Kneed and Feed, what strategies and tactics would be most effective in evacuating the occupants of this building and preventing extension?
7. Given the multiple occupancies (restaurant, retail, and residential), how would time of day impact on firefighting operations in this building and exposure?

While this building is in my response area, you have challenging buildings in yours as well. Time to find out what’s in your patch! When on a medical response, automatic alarm, performing fire inspections, or just eating breakfast, take the time to look around and ask yourself what if…. Building Factors are the first element in B-SAHF and they are present prior to the fire. Pre-incident planning either on a formal basis (best choice) or informally as an individual or company is essential to safe and effective incident operations.

Thanks!

I would like to extend a special thank you to the owners and staff of the Kneed and Feed for providing the opportunity to learn about their building. While challenging from a firefighting perspective, this is one of the best places to have breakfast or lunch (but particularly breakfast) in our District! If you are on Whidbey Island, stop in for a meal, but bring your appetite.

This post will finish up with Captain Mike Sullivan’s Fire Attack Questions. In the coming weeks I will explore the research conducted by UL, NIST, and FDNY on Governors Island last summer (see the video of a presentation on this research at FDIC later in this post). If you have questions or topics that you would like to see addressed in the CFBT-US Blog, please comment on the post or send me an e-mail.

In your Blog about gas cooling you mention combustion products and pyrolysis products. Combustion products being light heat and smoke but can you elaborate on pyrolysis products, are they just the gasses that are off gassing from the fuel?

Smoke is a complex aerosol comprised of gases, vapors, and particulates resulting from pyrolysis and incomplete combustion along with entrained air. So, smoke is comprised of both chemical products of pyrolysis (thermal decomposition of fuel) and combustion products. The chemical composition of smoke is extremely complex and depends on both the type(s) of fuel and conditions under which it is burning, predominantly limitations on ventilation and oxygen concentration.

Smoke is toxic, with incomplete combustion of organic fuels producing substantial amounts of carbon monoxide and nitrogen containing materials producing hydrogen cyanide. As smoke is a product of pyrolysis and incomplete combustion, it also contains a substantial percentage of unburned fuel, as such, smoke is fuel.

I have read that if smoke is venting from a building then there will be air entering from somewhere. During basement fires where the fire is below the neutral pressure plane you will often see smoke exiting from the front door from top to bottom of the doorway with no apparent entry of air (no neutral pressure plane) and no other vent opening. Could you comment on this?

The mass of smoke exiting from the building must equal the mass of the oxidized fuel and the mass of air entering the building as mass can neither be created or destroyed (law of conservation of mass) as illustrated below.

If you see smoke exiting from an opening with a unidirectional air track (out), air is entering somewhere else. Likely, air is entering from multiple locations without presenting an obvious indicator as to the flow paths involved.

Controlling the flow path in this case, involves closing the door. This acts in the same manner as closing the damper in a wood stove. Restricting the exhaust will slow intake of air and reduce the heat release rate until water can be applied (preferably making access through an exterior doorway at the basement level or applying water through a window to further reduce heat release prior to an interior attack.

Recent research by Underwriters Laboratories (UL), National Institute of Standards and Technology (NIST), and the Fire Department of the City of New York on Governors Island showed that closing an open front door reduced the heat release rate from a basement fire. Battalion Chief George Healey, Dan Madryzkowski, Steve Kerber, and Lieutenant John Ceriello provided an excellent presentation on this research at the 2013 Fire Department Instructors Conference. I strongly recommend viewing the presentation (embedded below)!

Scientific Research for the Development of More Effective Tactics

The following video recording provides an excellent overview of research conducted by UL, NIST, and FDNY on Governors Island to develop an understanding of fire dynamics in the modern fire environment and the influence of firefighting tactics on firefighter safety and effective fire control and ventilation operations.

This presentation was a seminal event in the US Fire Service that emphasized the importance of understanding fire behavior and the connection between solid research (both in the lab and in the field) with operational strategies and tactics. The research is solid, but it is important that all of us understand that it does not answer all of the questions and we should consider context when attempting to apply specific findings in general terms. For example:

• The suppression elements of the Governors Island tests were conducted using solid stream nozzles as that is the predominant type of nozzle used by FDNY. Tests showed that positive impact can be had using this type of nozzle. An important finding, but it was not intended to address the question of where are solid streams more effective than fog patterns (and where fog patterns are more effective).
• Tests were conducted on the Vent, Enter, Isolate, and Search (VEIS) tactic. Evidence points to the importance of controlling the flow path by closing the door. This does not mean that this is or is not an appropriate tactic under all circumstances or in all contexts, it simply addresses the importance of controlling the flow path.

The fire service owes a tremendous debt to UL, NIST, and FDNY (and in particular George, Dan, Steve, and John) for their commitment to improving firefighter safety and the effectiveness of firefighting operations. In order to maximize the value of this critically important research, it is essential that we explore the findings and underlying data and make sense of how this information can improve firefighting operations in our communities. More on this in subsequent posts!

Ed Hartin

Amazing!

Thursday morning saw a sea change in perspectives on fire behavior in the United States! Over 2500 people were in the big room at FDIC to hear BC George Healey (FDNY), Dan Madryzkowski (NIST), Steve Kerber (UL), and LT John Ceriello (FDNY) talk about fire research conducted on Governors Island in New York.

This excellent presentation emphasized the importance of understanding fire behavior and the influence of flow path and provided several key tactical lessons, including:

• Importance of control, coordination, and communication between crews performing fire attack and those performing tactical ventilation
• The effectiveness of anti-ventilation such as closing the door (even partially) on slowing fire development
• Effectiveness of water quickly applied into the fire compartment (from any location, but in particular from the exterior) in slowing fire progression
• The demonstrated fact that flow path influences fire spread and not application of water. You can’t push fire with water applied into the fire compartment.
• Importance of cooling the hot smoke (fuel) in the upper layer

Several years ago, who would have thought that a presentation on fire dynamics and research would have drawn this number of people to a presentation at FDIC. Kudos to FDNY, NIST, and UL for their ongoing work in developing an improved understanding of fire dynamics and firefighter safety.

FAQ (Fire Attack Questions) Continued

I had the opportunity to visit with Captain Mike Sullivan with the Mississauga Ontario Fire Department while at FDIC and we are continuing our dialog with another series of questions related to the characteristics of water fog and its use of a fog pattern for self-protection when faced with rapid fire progression in a structure fire.

The next three questions deal with using a fog stream for protection. In the IFSTA Essentials of Firefighting 5th edition it states that “wide fog patterns can also protect firefighters from radiant heat”, however in the IFSTA Essentials of Firefighting 3rd edition it states “In the past, water curtain broken stream nozzles were commonly used for exposure protection. However, research has indicated that these nozzles are only effective if the water is sprayed directly against the exposure being protected”. This tells me that fog patterns cannot protect from radiant heat.

Another question for which the answer is “it depends”. Both statements are correct (in context). Water droplets reduce radiant heat by absorbing energy and scattering the radiant energy. The effectiveness of these mechanisms depends on droplet size, wavelength of the radiation, geometric dimensions of the water spray, and density of the fog pattern. To put this in context, firefighters use a water spray for protection when approaching a flammable gas fire. In this context, the high density of the spray in proximity of the nozzle is quite effective. In contrast, application of a water spray between a fire and exposure is likely to be much less dense, and thus less effective in protecting the exposure than simply applying water to the exposure to keep its temperature <100^o C.

In the past there was a belief (which some still believe) that if you find yourself in a bad situation in a house fire you can simply switch to a wide fog and it develops an “umbrella of protection from the heat and fire”. I believe this to be false. What I do think has happened in the past is that firefighters have found themselves in a room with extreme rollover or even had pockets of unburned gas igniting around them. When they used this technique they didn’t protect themselves with an umbrella of fog protection but they cooled the smoke layer and made the situation better.

This also is an interesting question, there are incidents where firefighters have opened the nozzle when caught in rapid fire progression and have survived (not necessarily uninjured), likely due to the cooling effects of the water spray. However, I would agree that this does not provide “an umbrella of protection” like a force field that provides complete protection. The benefit is likely by cooling of the hot gases above and potentially controlling some of the flaming combustion in the immediate area. However, as continuous application will likely not only cool the hot upper layer, but also generate a tremendous amount of steam on contact with compartment linings, the environment will not be tenable in the long term. However, this environment is likely more survivable than post-flashover, fully developed fire conditions.

Much the same as in driving or riding in fire apparatus, the best way to avoid death and injury in a crash is to not crash in the first place. If firefighters recognize worsening fire conditions, they should cool the upper layer to mitigate the hazards presented, if this is ineffective, withdrawing while continuing to cool the upper layer is an essential response.

My last comment on this; and this is where I am not really sure. If you are in a situation where you need to back out quickly, would it work to use a fog stream to push the heat away as you are reversing out of the structure? You would only do this for a short time while you retreat.

If you cannot put water on the fire to achieve control (shielded fire) or the heat release rate (HRR) of the fire exceeds the cooling capacity of your stream you are in a losing position. When faced with rapidly deteriorating thermal conditions, it is essential to cool the upper layer. It is important to note that cooling, not simply “pushing the heat away” is what needs to happen in this situation. This action reduces heat flux from both convective and radiant transfer. Adequate water must be applied to accomplish this task, as temperature increases so too does the water required. Long pulses provide a starting point, but the pulses need to be long enough to deliver the required water. If needed, flow could be continuous or near continuous while the crew withdraws. In much the same manner a crew working with a solid stream nozzle would operate the nozzle in a continuous or near continuous manner and rotate the stream to provide some cooling to the upper layer while withdrawing.

There are those who believe that you can use a fog stream to protect yourself in a house fire by pushing the heat away from you as you advance on the fire. I believe you can push heat away from you and it happens in 2 distinct ways,  the wide fog with the entrained air is literally pushing the heat away from you and you have now created high pressure in an area that was low pressure (typically you are near an open door) so you have effectively changed the flow path. Having said this, I feel the benefits are short lived. With this fog pattern you will also be creating a lot of steam which will continue expanding until it’s temperature reaches equilibrium with the rest of the fire compartment (expansion could be as high as 4000 times). With all this pushing and expansion you are now creating high pressure in an area down stream from you that had previously been a low pressure area. As we know, everything is trying to move from high to low pressure, now the low pressure area is directly behind the nozzle. Now you are in a situation where not only is the heat coming back behind the nozzle but there is an enormous amount of steam being created and heading your way. The confusion here is most likely with the techniques we use when practicing for gas fires, we do this outside where there is an endless amount of space to push the heat away (I read this part in a good article in Fire Engineering).

The impact of continuous application of a fog stream (or any stream for that matter) as you advance is dependent on a number of factors, principal among which are the flow path and where steam is produced (in the hot gas layer versus on contact with surfaces). Continuous application is likely to result in vaporization of a significant amount of water on contact with surfaces; this will result in addition of steam to the hot upper layer without corresponding contraction of the hot gases that results from vaporization of water while it is in the gases. Without ventilation in front of the fog stream (or any stream for that matter), this can result in a reduction in tenability. However, when ventilation in front of the stream is provided, a combination attack (using a fog pattern, straight, or solid stream) can be quite effective for fully developed fire conditions.

I was hoping you could elaborate on the term “painting”. It is defined as a “gentle application of water to cool without excess steam production”. The hard part as a firefighter is the word “gentle” as this word doesn’t register in firefighter lingo. I can see this during overhaul but was hoping you could elaborate.

The way that I typically explain the concept of “gentle” is using a fire in a small trash can or other incipient fire inside of a building. If you use a hoseline to extinguish this fire, it is unlikely that you will need a high flow rate or application of the stream with the bail of the nozzle fully open. It would be appropriate to simply open the nozzle slightly on a straight stream and apply a small amount of water to the burning fuel.

Surface cooling can be done using a vigorous application from a distance when faced with a well involved compartment. In this situation, the reach of the stream is appropriately used to extinguish the fire and cool hot surfaces from a distance to minimize thermal insult to firefighters while quickly achieving control. However when faced with hot and pyrolizing compartment linings or contents, it may be useful or necessary to cool these surfaces from closer proximity. In this case applying water with force will result in much of the water bouncing off the surfaces and ending up on the floor. Painting involves using a straight stream or narrow fog pattern with the nozzle gated back to provide a gentle application resulting in a thin layer of water on the hot surface. As you note, this is most commonly used during overhaul, but could be used anytime that there is a need to cool hot, pyrolizing, but unignited surfaces.

Next week Mike and I will conclude this series of FAQ with a look at pyrolysis and flow path.

Captain Mike Sullivan with the Mississauga Ontario Fire Department and I are continuing our dialog with another series of questions related to the science behind fire attack and fire control methods. Mike’s next several question deal with gas and surface cooling.

I know the best way to extinguish a fire is to put water on it but my questions below deal with a situation of large, open concept homes where you can see the entire main floor except the kitchen cooking area, in many cases this area is not separate from the open floor plan but around the corner so we can’t hit the fire until we get around that corner. My questions are all geared around how to cool the environment as you make your way to the fire (if you need to go to the very back of the house to get to the fire, fire can’t be seen).

When you answered the question about the effects of flowing a straight/solid stream across the ceiling it sounds as if this is really only surface cooling and not effectively gas cooling. If this is true then I was wondering what the value of doing this is, what are the main benefits of cooling the ceiling, walls and floor (and any furniture etc. the water lands on)? Also, what do you recommend to those departments that only use solid bore nozzles?

Use of a solid (or straight) stream off the ceiling has some effect on cooling the gases, but this is limited as the droplets produced are quite large and do not readily vaporize in the hot upper layer (great for direct attack, but not so much for gas cooling). The value of doing this is that any energy taken out of the hot upper layer (buy cooling the gases or by cooling surfaces and subsequent transfer of energy from hot gases to the cooler surfaces) will have some positive effect. In addition, hot combustible surfaces, depending on temperature are likely pyrolizing and adding hot, gas phase fuel to the upper layer. Cooling reduces pyrolysis and the fuel content of the smoke overhead.

The following video of the “Nozzle Forward”, Aaron Fields, Seattle Fire Department demonstrates some excellent hose handling techniques and also provides an illustration of how a solid stream nozzle can be used to cool hot gases by breaking up the stream on contact with compartment linings. Have a look at the video between 2:00 and 2:30 where the nozzle is being rotated as in a combination attack while advancing down a hallway. Note that the stream breaks up on contact with the ceiling and walls, providing a distribution of large droplets in the overhead area.

This technique can be quite effective when faced with a large volume of fire and ventilation is provided in front of the fire attack. However, if the hallway is not involved in fire, but there is a hot layer of smoke overhead, this approach is less effective as large droplets are less efficient in cooling the hot gases and much of the water will end up on the floor, not having done appreciable work.

While this will likely generate some hate and discontent, I would recommend that departments using only solid stream nozzles reconsider their choice. This type of nozzle has a number of great characteristics, but also has a number of significant limitations, principal among which is limited ability to cool the hot upper layer when dealing with shielded fires. That said, the firefighter riding backwards or company officer in the right front seat may have limited impact on this decision (at least in the short term). If all you have to work with is a solid stream nozzle, directing the stream off the ceiling to break up the pattern and provide limited gas cooling when dealing with extremely hot gases overhead are likely a reasonable option.

I understand how penciling a fog stream in the hot gas layer is the best way to cool the gases. My concern is this, where I work there are many new homes with open concept, large rooms and little compartmentation. I like the idea of cooling the gases above my head but I still have a large room full of gases that could still flash. Sure I’m cooling the gases around me but if the gases at the other end of the open space flash, I am still in the same room and in trouble. I would prefer to cool that area before I get there. What are your recommendations for this situation?

As a point of clarification, we use the term “penciling” in reference to an intermittent straight stream application. Gas cooling is most effectively accomplished with pulsed or intermittent application of water fog. We refer to this technique as “pulses” (to differentiate this from penciling with a straight or solid stream)

We also have quite a few large residential occupancies with open floor plans. The issue of large area or volume compartments also applies in commercial and industrial building as well. Gas cooling simply provides a buffer zone around the hose team, but other than in a small compartment does not change conditions in the upper layer throughout the space. Gas cooling must be a continuous process while progressing towards a shielded fire. The upper limit of area (or more appropriately volume) is an unanswered question. My friend Paul Grimwood, Principal Fire Safety Engineer with the Kent Fire and Rescue Service in the UK holds that the upper limit with a relatively normal ceiling height is approximately 70 m² (753 ft²). Paul’s perspective is anecdotal and not based on specific scientific research. However, this is not unreasonable, given the reach of a narrow fog pattern and vaporization of water as it passes through the upper layer. Given the higher flow rates used by the North American fire service, it may be possible to control a somewhat larger area than Paul suggests, but this remains to be determined.

As to an answer to this problem, pulsed application does not always mean short pulses, multiple long pulses with a narrow pattern or a sweeping long pulse may be used to cover a larger area. In addition, large area compartments or open floor plan spaces may require multiple lines to adequately control the environment. The purpose of the backup line is to protect the means of egress for the attack line and this is of paramount importance in an open plan building.

The following two videos demonstrate the difference between short and long pulses. At 115 lpm (30 gpm) the flow rates in these two videos are low by North American standards, but are fairly typical for gas cooling applications in many parts of the world. Short pulses can be used effectively up to approximately 570 lpm (150 gpm) with minimal water hammer, for higher flow rates, long pulses are more appropriate.

When we do these quick bursts of fog to cool the gases we are not using much water compared to the feeling that the best way to handle this is to flow a large amount of water and basically soak the entire area down before you advance through it. I was hoping you could comment on this.

As noted in the answer to your previous question, pulses are sometimes, but not always quick. In a typical legacy residence (small compartments) short pulses are generally adequate to cool hot gases overhead. When accessing a shielded fire, and cooling the hot gases overhead it is not generally necessary to cool hot surfaces and fuel packages such as furniture (it may be a different story in the fire compartment). Water remaining on the floor or soaked into contents did not do significant work and simply added to fire control damage. We should not hesitate to use an adequate amount of water for fear of water damage, but tactical operations should focus on protecting property once (or while) we are acting to ensure the safety of occupants and firefighters.

We often enter house fires where the house is full of smoke but the smoke is not necessarily very hot. In these cases we would not normally cool the gases. From what we understand now, smoke is fuel and with open concept homes this smoke could ignite close to the fire therefore igniting the smoke nearer to us. What I was wondering is what are you teaching in regards to cooling the smoke, do you do it only when you feel a lot of heat or start cooling regardless?

As the temperature of the upper layer drops, the effectiveness of application of pulsed water fog diminishes. That said, if the upper layer is hot enough to vaporize some of the water (i.e. above 100^o C), application of water will further cool the gases and provide some thermal ballast (the water will have to be heated along with the gases for ignition to occur).

When presented with cold (< 100^o C) smoke, firefighters still face a hazard as gas phase fuel can still be ignited resulting in a flash fire (if relatively unconfined) or smoke explosion. The only real solution to this hazard is to create a safe zone by removing the smoke through tactical ventilation.

Mike and I will continue this dialog next week with a discussion of the protective capabilities of fog streams.

Captain Mike Sullivan with the Mississauga Ontario Fire Department and I are continuing our dialog with another series of questions related to the science behind fire attack and fire control methods.

The first several questions pertain to the video produced by the Kill the Flashover project illustrating the impact of anti-ventilation on heat release rate and compartment temperature.

Would you happen to know what type of building this was done in (house or concrete burn building) and what fuel was used?

KTF 2011 and 2012 were conducted  in acquired structures and KTF 2013 was conducted in a purpose built burn building. Each of the KTF burns used normal types of building contents to provide realistic fire conditions for the demonstrations/experiments. The first burn in KTF 2011 use a fuel load consisting of a chair, small amount of wood, carpet and carpet pad (as illustrated below).

You mentioned in the “Kill the Flashover” video about the key to heat reduction is the lack of oxygen for the heat release. I understand this but still wonder where all this heat goes, does it not have to dissipate somewhere?

The following video was shot during the first burn in KTF 2011. As previously discussed, the fuel load was comprised of a chair, carpet, carpet pad, and a small amount of wood. At the start of the burn the only opening to the compartment was a typical sized residential doorway. After the fire became well developed the door was closed.

You are absolutely correct! A compartment fire is an open thermodynamic system in which there is an ongoing transfer of mass (e.g., smoke out and air in) and energy between the system and its environment. This leads to another excellent question.

We often speak about fire and how the box “can’t absorb any more heat” and this is usually the point where we start to near flashover, this is what we thought was occurring, the box was simply continuing to absorb heat.

The phrase “can’t absorb any more heat” is scientifically incorrect, unless the “box” and the flames or hot gases are all of equal temperature. If any portion of the compartment or fuel packages within the compartment are lower than the temperature of flames or hot gases, the temperature of this matter will continue to increase (until thermal equilibrium is reached). The oversimplified explanation likely relates to the endothermic (heat absorbing) process of pyrolysis and transition to the exothermic (heat releasing) process of combustion.

Any object with a temperature above absolute zero transfers thermal energy to objects having a lower temperature. In a compartment fire energy released by the combustion reaction is transferred to materials within the thermodynamic system through radiation, conduction, and convection (as illustrated below).

Under fire conditions, increasing temperature in the compartment is the result conversion of chemical potential energy in the fuel to thermal energy through combustion. When the rate of energy released exceeds losses of thermal energy to the thermodynamic surroundings, temperature increases. When heat release rate is reduced by limiting the oxygen available for combustion (i.e. closing the door), continued transfer of energy to the thermodynamic surroundings results in a drop in temperature.

This is somewhat like bringing a pot of water on the stove to a boil and then removing it from the burner. Once off the burner, the water continues to transfer energy to its surroundings and will begin to cool.

FAQ-Fire Attack Questions will continue next week with a discussion of gas cooling, fog patterns and solid or straight streams, and limitations encountered when working in large volume spaces!.

Video of several incidents involving explosions during structural firefighting operations have been posted to YouTube in the last several weeks. Two of these videos, one from New Chicago, IN and the other from Olathe, KS involve residential fires. The other is of a commercial fire in Wichita, KS.

When a video shows some sort of spectacular fire behavior there is generally a great deal of speculation amongst the viewers about what happened. Was it a smoke (fire gas) explosion, backdraft, flashover, or did something else happen? Such speculation is useful if placed in the framework of the conditions required for these phenomena to occur and the Building, Smoke, Air Track, Heat, and Flame (B-SAHF) indicators that provide cues of to current fire conditions and potential fire behavior.

Occasionally, what happened is fairly obvious such as flashover resulting from increased ventilation under ventilation controlled conditions. However, the phenomena and its causal factors are often much more of a puzzle.

Download and print three copies of the B-SAHF Worksheet.

Residential Fire-Olathe, KS

Limited information was posted along with this pre-arrival video of a residential fire in Olathe, KS. The home was unoccupied when the fire occurred.

Watch the thirty seconds (0:30) of the video. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators; then answer the following five standard questions (based only on what you observe during the first thirty seconds of the video)?

1. What additional information would you like to have? How could you obtain it?
2. What stage(s) of development is the fire likely to be in (incipient, growth, fully developed, or decay)?
3. What burning regime is the fire in (fuel controlled or ventilation controlled)?
4. What conditions would you expect to find inside this building?
5. How would you expect the fire to develop over the next two to three minutes

Watch remainder of the video and consider the following questions:

1. Did fire conditions progress as you anticipated?
2. What changes in the B-SAHF indicators did you observe?
3. What may have caused the explosion (consider all of the possibilities)?
4. Were there any indications that may have given warning of this change in conditions?

Residential Fire-New Chicago, IN

Companies from New Chicago and Hobart were dispatched to a reported house fire at 402 Madison in New Chicago, IN on February 17, 2012.

Watch the thirty seconds (0:30) of the video. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators; then answer the following five standard questions (based only on what you observe during the first thirty seconds of the video)?

1. What additional information would you like to have? How could you obtain it?
2. What stage(s) of development is the fire likely to be in (incipient, growth, fully developed, or decay)?
3. What burning regime is the fire in (fuel controlled or ventilation controlled)?
4. What conditions would you expect to find inside this building?
5. How would you expect the fire to develop over the next two to three minutes

Watch remainder of the video and consider the following questions:

1. Did fire conditions progress as you anticipated?
2. What changes in the B-SAHF indicators did you observe?
3. What may have caused the explosion (consider all of the possibilities)?
4. Were there any indications that may have given warning of this change in conditions?

Commercial Fire-Wichita, KS

Wichita Fire Department on scene of a working building fire in large, non-combustible commercial building. Extreme heat and fire conditions cause an unknown cylinder to explode.

Keep in mind that gas cylinders and other closed containers can result in explosions during structural firefighting operations. Unlike backdraft and smoke explosion, the only clue may be building factors related to occupancy (and this may not be a good indicator when operating at a residential fire).

Wichita Fire Department on scene of a working building fire in a large metal structure. Extreme heat and fire conditions cause an unknown cylinder to explode. If you listen close, you can hear it vent before it goes off. Concussion actually cuts out my audio for just a couple seconds. No one was injured.

Video by Sean Black Photography http://seanblackphotography.smugmug.com/

Firefighter Safety

Potential for explosions related to extreme fire behavior such as backdraft and smoke explosion may be recognized based on assessment and understanding the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) indicators. Other types of explosions such as those resulting from failure of closed containers (e.g., containing liquids or gases) may be a bit more difficult as this potential is likely to be present in most types of occupancies. However, commercial and industrial occupancies present greater risks.

Recognizing that even with sound experienced judgment, there may be undetected hazards on the fireground. Managing the risk requires developing a solid knowledge base and skills and operating within sound rules of engagement such as the IAFC Rules of Engagement for Structural Firefighting. However, considering the hazards presented by rapid fire progression and potential for changes in conditions following explosive events, I would add the following:

• Base your strategies and tactics on current and anticipated fire behavior and structural stability.
• Ensure that members correctly wear complete structural firefighting clothing and SCBA when working in the hazard zone and practice good air management. Buddy check before entry!
• Crews operating on the interior should have a hoseline or be directly supported by a crew with a hoseline. If conditions deteriorate, a hoseline allows self-protection and provides a defined egress path.
• Have well practiced battle drills for tactical withdrawal and abandoning the building (depending on conditions). See Battle Drill, Battle Drill Part 2, and Battle Drill Part 3.

Next…

My next post will address the impact of a closed door on tenability during a residential fire as the ninth tactical implication identified in the UL study on the Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction.

Subsequent posts will come back to the Olathe, KS and New Chicago, IN residential fires to examine potential impacts on fire behavior and explosions that resulted during these incidents.

Ed Hartin, MS, EFO, MIFIreE, CFO

Seven Firefighters Injured

Seven firefighters were tragically injured in Prince George’s County Maryland on Friday, February 24, 2012. The fire broke out in the basement of a single-family, one-story house located at 6404 57^th Avenue in Riverdale, MD shortly after 21:00 hours.

Note: View from Alpha-Bravo Corner street side. Photo by Billy McNeel.

On arrival, Engine 807B reported a two-story, single family dwelling with fire showing from the basement level on Side Bravo. Seven members from Companies 807 (Riverdale) and 809 (Bladensburg) entered Floor 1 of the building on Side A (East Side) and within eight seconds were enveloped by untenable, wind driven fire conditions. Preliminary reports indicate that firefighters had initiated an interior attack on the fire when a sudden rush of air, fanned by high winds, entered from the rear of the house either from a door or window being opened or broken out. (Brady, 2012). A report on Monday, February 27 indicated that some of the firefighters ran to the back of the one-story home, then entered through a basement door while other members of their company opened the front door in search of a victim (FirefighterNation, 2012).

In a statement to Washington Post reporter J. Freedom du Lac (2012), Chief Marc Bashoor indicated that strong winds were gusting out of the west at up to 40, 45 mph, blowing directly into the burning basement, which had a west-facing door. “As soon as the guys opened the front door and advanced, it blew from the basement, up the steps and right out the front door,” Bashoor said. “It was like a blowtorch coming up the steps and out the door… Without that wind, the hot air and gases would have been venting out of the rear of the house,” he said. “The current of air essentially produced a chimney right up the steps and out the front door.” (Washington Post, 2012).

Firefighters Ethan Sorrell and Kevin O’Toole from Bladensburg Volunteer Fire Department remain in critical condition at Washington Hospital Center. Riverdale Volunteer, Michael McLary also remains hospitalized for injuries. The other injured firefighters were released and sent home Saturday evening according to the latest reports.

The wind-fueled fireball that injured seven Prince George’s County firefighters when it blew through the burning house they had just entered was “a freak occurrence,” a department spokesman, Mark Brady, said Saturday (du Lac, 2012).

Chris Naum at Command Safety has an excellent post examining the fire building and weather conditions at the time of the incident. See Residential Fire Injures Seven Firefighters: Wind Driven Conditions Suspected.

Freak Occurrence?

Dealing with an accident involving a serious injury or fatality is extremely difficult, particularly when the complete circumstances and eventual outcome is unknown. What may appear to be obvious in retrospect may also have been not so clear to the individuals engaged in emergency operations. However, one might ask if the fire behavior encountered at 6404 57^th Avenue in Riverdale, MD was in fact a freak occurrence. A freak is defined as a thing or occurrence that is abnormal, markedly unusual or irregular.

The conditions encountered were markedly different than usually encountered in fires occurring in single family dwellings. However, the conditions described in this incident are not unusual when considered in light of the building configuration and wind conditions at the time of the incident. Wind, flow path, and burning regime (fuel or ventilation controlled) have a tremendous impact on fire behavior and potential for rapid fire progression resulting in untenable conditions.

Wind Driven Fires

On April 16, 2007 Technician Kyle Wilson of the Prince William Fire & Rescue lost his life in a wind driven fire occurring in a large, single family dwelling. In the introduction to the investigative report produced by Prince William Fire & Rescue examining this incident, Chief Kevin J. McGee states:

First, the impact the wind had on this event was significant. While weather conditions, and specifically wind, are often discussed in the firefighting environment of wildland fires, it does not receive the same attention and consideration in structure fires. This incident showed the dramatic and devastating effect the wind can have on the spread of fire in a building. The wind forced the fire into the building and caused the sudden change in fire conditions inside, including the “blowtorch” effect witnessed by the crews on the scene (Prince William County Fire Rescue, 2008)

In January, the National Institute of Standards and Technology (NIST) released Simulation of the Dynamics of a Wind-Driven Fire in a Ranch-Style House-Texas (Barowy & Madrzykowski, 2012) examining fire behavior in the incident that took the lives of Houston Fire Department Captain James Harlow and Firefighter Damion Hobbs on April 12, 2009 while engaged in firefighting operations in a single family dwelling. This report emphasized that potential for wind driven fire conditions can occur in all types of buildings, including single-family residential structures.

NIST research (Madrzykowski & Kerber.(2009a, 2009b) has identified that wind driven fire conditions can be created with wind speeds as low as 4.5 m/s (10 mph) and that while structural fire departments have recognized the impact of wind on fire behavior, in general, standard operating guidelines (SOG) have not changed to address the risk of wind driven fires (Barowy & Madrzykowski, 2012).

Previous posts have examined NISTs research on the issue of wind driven fires:

• Wind Driven Fires
• NIST Wind Driven Fire Experiments: Establishing a Baseline
  
• NIST Wind Driven Fire Experiments: Anti-Ventilation-Wind Control Devices
  
• NIST Wind Driven Fire Experiments: Wind Control Devices & Fire Suppression

Flow Path

On May 30, 1999, Firefighters Anthony Phillips and Louis Matthews of the District of Columbia Fire Department (DCFD) died and two others were severely injured as a result of rapid fire progression while engaged in firefighting operations at 3146 Cherry Road, NE. The fire occurred in the basement of a two-story, middle of building, townhouse apartment. Crews entered on Floor 1, Side A and were caught in the flow path of hot smoke and flames when a sliding glass door was opened at the Basement Level on Side C. Previous posts examined this incident in detail:

• Fire Behavior Case Study Townhouse Fire: Washington, DC
  
• Townhouse Fire: Washington, DC What Happened
• Townhouse Fire: Washington, DC Extreme Fire Behavior
  
• Townhouse Fire: Washington, DC: Computer Modeling
• Townhouse Fire: Washington, DC Computer Modeling-Part 2

More recently, the City of San Francisco Fire Department released an investigative report examining the circumstances surrounding the deaths of Lieutenant Vincent Perez and Firefighter/Paramedic Anthony Valerio on June 2, 2011 while operating at a fire in the basement of a two story home with two levels below grade. Failure of a basement window placed the Lieutenant and Firefighter in the flow path between the basement window and their entry point on Floor 1. The investigative report produced by the San Francisco Fire Department details their findings and recommendations related to this incident.

Safety Investigation Report Line-of-Duty Deaths, 133 Berkley Way, June 2, 2011, Box 8155, Incident #11050532

Structural Firefighting Under Wind Conditions

Research and fireground experience point to the following:

• Building configuration including windows, doors, and open interior stairways can have a significant impact on development of a flow path from the fire to one or more exhaust points.
• Introduction of additional air to a ventilation controlled fire (without concurrent fire suppression) will quickly result in increased heat release rate.
• Creation of openings at and above the fire level which result in a flow path with an exhaust opening above the inlet will result in a rapid increase in heat release rate.
• Thermal conditions in the flow path above the fire and/or downstream from the fire location or will quickly become untenable.
• Even limited wind conditions can result in wind driven fire conditions.
• These factors in combination are even more likely to result in rapid fire progression and untenable conditions in the downstream flow path.

It is essential that Firefighters and Fire Officers recognize the influence of ventilation on fire behavior and potential for wind driven fire conditions and adjust their strategies and tactics accordingly. The following guidance is based on recommendations developed through the NIST wind driven fires research as well as data from National Institute for Occupational Safety and Health (NIOSH) death in the line of duty reports and incident investigative reports by the Texas State Fire Marshals Office.

Potential for wind driven conditions increases directly with wind speed. When wind speeds exceed a gentle breeze (8-12 mph) consider the potential for wind driven fire conditions and apply the following strategic and tactical considerations (CWIFR District Board, 2011):

• If potential for wind driven fire conditions is identified, this should be communicated to all companies and members working at the incident as a safety message.
• When possible, operate from the exterior and apply water from upwind directly into the involved compartments prior to interior attack. Even low flow exterior streams applied from upwind can have a significant impact on controlling the fire prior to interior operations).
• In a wind-driven fire, it is most important to use the wind to your advantage and attack the fire from the upwind side of the structure, especially if the upwind side is the burned side. Note that this may be contrary to conventional offensive tactics that place hoselines between the hazard presented by the fire and potential occupants and uninvolved property.
• Avoid pressurization of the building without first establishing adequate exhaust openings (2-3 times larger than the inlet). Remember that wind can create the same (or greater) positive pressure as a blower used in positive pressure ventilation (PPV). Pressurization without adequate exhaust can result in extreme fire behavior. Note: This is particularly important when the fire is on the leeward (downwind) side of the building and entry is made from the windward (upwind) side of the building.
• Consider controlling the flow path by using anti-ventilation such as door control and limiting the use of (horizontal and vertical) tactical ventilation prior to fire control. However, it is essential to remember that unplanned ventilation resulting from fire effects can have a significant impact on the ventilation profile and subsequent flow path(s).
• Avoid working in the exhaust portion of the flow path (between the fire and exhaust opening) or potential flow paths (between the fire and potential exhaust openings). Unplanned ventilation from fire effects can suddenly change the interior thermal conditions.
• Identify potential refuge areas, escape routes, and safety zones prior to and during interior operations. Taking refuge in a compartment with an intact and closed door may temporarily provide tenable conditions and a place of refuge until the fire can be controlled or another avenue of egress established.

References & Additional Reading

Brady, M. (2012). Seven firefighters injured battling Riverdale house fire. Retrieved February 26, 2012 from http://pgfdpio.blogspot.com/2012/02/seven-firefighters-injured-battling.html

Central Whidbey Island Fire & Rescue (CWIFR) District Board. (2011). Board minutes February 9, 2012. Coupeville, WA: Author. [Adoption of Purpose, Policy, and Scope of SOG 4.3.6 Structural Firefighting Under Wind Conditions]

District of Columbia (DC) Fire & EMS. (2000). Report from the reconstruction committee: Fire at 3146 Cherry Road NE, Washington DC, May 30, 1999. Washington, DC: Author.

du Lac, J. (2012). Blaze that injured 7 Prince George’s firefighters called ‘freak occurrence’. Retrieved February 26, 2012 from http://www.washingtonpost.com/local/blaze-that-injured-7-prince-georges-firefighters-called-freak-occurrence/2012/02/25/gIQAdGJMaR_story.html?hpid=z3

FirefighterNation. (2012). Critically burned in Maryland house fire, firefighters face long recovery. Retrieved February 28, 2012, from http://www.firefighternation.com/article/news-2/critically-burned-maryland-house-fire-firefighters-face-lengthy-recovery.

Madrzykowski , D. &  Barowy, A. (2012). Simulation of the dynamics of a wind-driven fire in a ranch-style house – Texas, TN 1729. Retrieved February 8, 2012 from http://www.nist.gov/customcf/get_pdf.cfm?pub_id=909779

Madrzykowski, D & Kerber, S. (2009a). Fire fighting tactics under wind driven conditions: Laboratory experiments, TN 1618. Retrieved February 8, 2012 from http://fire.nist.gov/bfrlpubs/fire09/PDF/f09002.pdf

Madrzykowski, D & Kerber, S. (2009b). Fire fighting tactics under wind driven fire conditions: 7-story building experiments, TN 1629. Retrieved February 8, 2012 from http://fire.nist.gov/bfrlpubs/fire09/PDF/f09015.pdf

Madrzykowski, D. & Vettori, R. (2000). Simulation of the Dynamics of the Fire at 3146 Cherry Road NE Washington D.C., May 30, 1999, NISTR 6510. August 31, 2009 from http://fire.nist.gov/CDPUBS/NISTIR_6510/6510c.pdf

National Institute for Occpational Safety and Health (NIOSH). (2008). Death in the line of duty…2007-12. Retrieved February 9, 2012 from http://www.cdc.gov/niosh/fire/pdfs/face200712.pdf

National Institute for Occpational Safety and Health (NIOSH). (2009). Death in the line of duty…2009-11. Retrieved February 9, 2012 from http://www.cdc.gov/niosh/fire/pdfs/face200911.pdf

National Institute for Occpational Safety and Health (NIOSH). (2009). Death in the line of duty…2007-29. Retrieved February 9, 2012 from http://www.cdc.gov/niosh/fire/reports/face200729.html

National Institute for Occupational Safety and Health (NIOSH). (1999). Death in the line of duty, Report 99-21. Retrieved August 31, 2009 from http://www.cdc.gov/niosh/fire/reports/face9921.html

Prince William County Department of Fire & Rescue. (2007). Line of duty death investigative report. Retrieved February 9, 2012 from http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCgQFjAB&url=http%3A%2F%2Fwww.iaff.org%2Fhs%2FLODD_Manual%2FLODD%2520Reports%2FPrince%2520William%2520County%2C%2520VA%2520-%2520Wilson.pdf&ei=b3dKT8LyGfHSiALt5tnrDQ&usg=AFQjCNFBBTfVkWIREXw0-wbd978fWSoP8w&sig2=y6_OEeJvhFSggiKioMESaw

San Francisco Fire Department. (2012). Safety Investigation Report Line-of-Duty Deaths, 133 Berkley Way, June 2, 2011, Box 8155, Incident #11050532 Retrieved February 26, 2012 from http://statter911.com/files/2012/02/Safety-Investigation-133-Berkeley-Way-Printable.pdf

Texas State Fire Marshal’s Office. (2007). Firefighter fatality investigation, Investigation Number FY 07-02. http://www.tdi.texas.gov/reports/fire/documents/fmloddnoonday.pdf

Texas State Fire Marshal’s Office. (2009). Firefighter fatality investigation, Investigation Number FY 09- http://www.tdi.texas.gov/reports/fire/documents/fmloddhouston09.pdf

Kerber, S. (2011). Impact of ventilation on fire behavior in legacy and contemporary residential construction. Retrieved July 16, 2011 from http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/ventilation/DHS%202008%20Grant%20Report%20Final.pdf

Residential Fire

This post examines fire development during a residential fire in Lyons, New York.

Download and the B-SAHF Worksheet.

Watch the first minute and thirty seconds (1:30) of the video. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators; then answer the following five standard questions?

1. What additional information would you like to have? How could you obtain it?
2. What stage(s) of development is the fire likely to be in (incipient, growth, fully developed, or decay)?
3. What burning regime is the fire in (fuel controlled or ventilation controlled)?
4. What conditions would you expect to find inside this building?
5. How would you expect the fire to develop over the next two to three minutes

In addition, consider how the answers to these questions impact your assessment of the potential for survival of possible occupants.

Now watch the video clip from 1:30 until 2:00. Now answer the following questions:

1. Did fire conditions progress as you anticipated?
2. What changes in the B-SAHF indicators did you observe?
3. What indications of fire stream effectiveness did you observe?
4. What potential avenues of fire extension would you consider based on the type of construction and building design?

As you watch the remainder of the video, consider the changes in observed conditions and what information this might provide the Incident Commander. What information should interior crews report to Command during this stage of incident operations.

More on Reading the Fire

See the following posts for more information on reading the fire:

• Reading the Fire” How to Improve Your Skills
• Reading the Fire: Building Factors
• Reading the Fire Building Factors Part 2
• Reading the Fire: Building Factors Part 3
• Reading the Fire: Smoke
• Reading the Fire: Smoke Part 2
• Reading the Fire: Air Track
• Reading the Fire: Air Track Part 2
• Reading the Fire: Heat
• Reading the Fire: Heat Part 2
• Reading the Fire: Heat Part 3
• Reading the Fire: Flames
• Reading the Fire: Flames Part 2
• Reading the Fire: Putting it All Together
• Incipient Stage Fires: Key Fire Behavior Indicators
• Growth Stage Fires: Key Fire Behavior Indicators
• Fully Developed Fires: Key Fire Behavior Indicators
• Decay Stage Fires: Key Fire Behavior Indicator

Ed Hartin, MS, EFO, MIFireE, CFO