Research results: Coordination of suppression, ventilation in multi-family dwellings
Key takeaways from UL FSRI latest experiments reviewing how coordinated fireground activities impact suppression efforts and victim tenability
This is the third in a three-part series of articles about the UL Firefighter Safety Research Institute’s recent analysis of coordinated fire attack operations. Read Part 1 about the coordination of suppression and ventilation in single-family homes and Part 2 about the impact of ventilation on strip mall fires.
Multi-family and apartment fires are some of the most dangerous types of incidents for both residents and firefighters. Whether tenements, townhouses, apartments or condominiums, some form of multi-family dwelling exits in nearly every fire department’s response area.
The UL Firefighter Safety Research Institute (FSRI) published in late June their latest study, Analysis of the Coordination of Suppression and Ventilation in Multi-Family Dwellings, which further discusses the need for coordination between suppression and ventilation at structure fires. This research follows two previous studies published earlier this year:
- Analysis of the Coordination of Suppression and Ventilation in Single-Family Homes
- Exploratory Analysis of the Impact of Ventilation on Strip Mall Fires.
Structure types used
In this latest research, four 10-family apartment buildings were acquired in Marietta, Georgia, with the assistance of the Cobb County (Georgia) Fire and Emergency Services.
Each of the acquired structures was wood-frame Type V construction with vinyl siding. The identical layout of each structure consisted of four apartments located on the first and second floors, and two garden-level apartments below ground level when viewed from the A side of each structure. However, these garden-level apartments had the same configuration as those above them, including a wooden deck walk-out from the bedroom, but at a lower elevation of approximately 20 feet due to the typography of the area. All of the wooden deck doors, as well as kitchen and bedroom windows, lined up with each apartment above it. All 10 apartment units used a common entry breezeway door for access on the A side of the structures.
Each apartment totaled 800 square feet of living space.
Detailing 13 experiments
A series of 13 experiments were completed in these four acquired structures. Researchers evaluated six different scenarios grouped by the fire’s point of origin (bedroom, kitchen, living room) and the initial ventilation conditions (no ventilation – all doors and windows closed; partial ventilation – a door or window partially open; or several doors or windows open). This was to study the flow paths of gases, and the change in those flow paths with the introduction of additional open doors or various types of ventilation activities. Each scenario except one used the same types of furnishings in each location to help maximize standardization.
In the kitchen area, a trash can was ignited. In the living room, the ignition began in a sofa cushion. And in the bedroom, the mattress and bed clothing were used. All fires used a remote electric match as the ignition device.
Suppression was conducted using 200 feet of 1¾-inch line with either a smoothbore nozzle with a 7/8-inch tip or a combination nozzle set on straight stream. Both devices flowed between 150 to 160 gpm.
Fire crews used the “flow and move” method, meaning that water was flowing as they moved or changed position during part of the extinguishment. Nozzles were set to straight streams, and an “O” movement pattern aimed at the ceiling was used to help distribute water over a larger area of the fire room.
The experiments also examined the tenability of possible victims by measuring the concentrations of certain gases (carbon monoxide, carbon dioxide and oxygen) in the apartment of origin; in apartments within the structure; and the common stairwell in scenarios where doors were closed or left open. These measurements were also taken when four ventilation techniques – positive pressure ventilation (PPV), positive pressure attack (PPA), hydraulic ventilation (HV), and door control (DC) – were employed during firefighter interventions.
Of the 13 experiments, seven were initiated in bedrooms, four in kitchens, and two in living rooms. Two bedroom and two living room fires were conducted in the lower-level garden apartments. Five bedroom fires were conducted on the first floor, while two kitchen fires were conducted on the first floor and two more on the second floor.
Two study standouts
When reading the study, two of the 13 experiments stood out to me as particularly critical factors.
Experiment 1A: In the first garden-level bedroom fire, all doors and windows were closed except for the door connecting the bedroom to the living room. During the initial fire build-up, that connecting hollow core bedroom door closed by itself due to the changing dynamics of the fire flow path. With all doors and windows closed, this essentially caused the fire to become oxygen-limited and self-extinguished.
It also shows in this case that the closed hollow core bedroom door allowed a safe haven in the remainder of the apartment where smoke and heat never reached an untenable level. While there was some damage in the bedroom area, the damage to the kitchen and living room area was limited to a slight amount of soot from smoke damage. That scenario was overhauled with a 2½ gallon water can.
Experiment 5: The other extreme was also during a garden apartment living room fire, with both the apartment door to the stairwell and the outside bedroom deck door left open. Two apartment doors on the second floor were initially left open to simulate what might happen when a tenant is escaping their apartment without closing their apartment door.
The fire grew rapidly to the point where the interior fire crew using the “flow and move” technique with a 1¾-inch line could not make it past the landing of the common entry breezeway door down to the open garden apartment fire below due to the excessive heat and the chimney effect of the products of combustion in the stairwell.
These hot gases extended upward the entire length of the interior stairwell, then into the open doors of the second-floor apartments. The interior crew requested that this fire be hit from the exterior, and after doing so, the temperature and smoke conditions improved within 30 seconds, allowing them to make it to the lower landing and subsequently enter and finish extinguishing the living room fire.
It should be noted that early into the fire, one of the second-floor apartment doors was closed while the other was left open. The heat damage and recorded data from the open-door apartment show how quickly that apartment became untenable, lessening the possibility of survival for anyone trapped with an open door. By contrast, when the outer door to the second apartment was closed, neither the temperature nor the concentration of gases reached the untenable level.
Apartment fire personal experience
During my fire service career, I have seen several dozen working apartment fires, many of which needed additional alarms to handle. After reading the most recent UL FSRI study, two of those fires quickly came to mind.
Doors open: The first was a 4 a.m. fire at a three-story apartment building in a neighboring community. My department provided the first-due ladder and medic unit on the initial dispatch. From the tone in the dispatcher’s voice, I could also tell this was not going to be an ordinary fire.
As I started my response, the first-due engine marked on the scene with heavy fire showing, my mental picture of the building, with a driveway off the dead-end of a residential street, reminded me that water supply would also be an issue.
The dispatcher began calling the first-due engine to give them additional information. After several tries, I told dispatch I was two minutes out and they could give me any additional information. That was when she said the police officer on the scene had reported several jumpers from the third floor. At that point, I could see the fire and told her to dispatch a third alarm with two additional medic units. We would need most of that assignment to stretch a second and third supply line, both in part from adjacent streets that required personnel to hand-lay those supply lines through nearby wooded areas.
The initial fire on the first floor had ignited in a bedroom, but that tenant left the door to the stairwell open as he left the scene. Some of the remaining families were able to make it past that apartment door before it flashed over, but some of those also left their apartment doors open. The combination quickly made the fire untenable and gave the other remaining tenants two choices: wait for rescue over ladders or a high-risk jump.
Containment works: The second apartment fire had a better outcome. The first-due engine officer in his size-up realized the interior stairwell was on fire and already blocked any possible exit. He indicated at the end of his size-up that his unit was in the “Rescue Mode” – a term that means they were going to get to those who needed rescue.
With a crew of four, the officer told his apparatus officer to get the second-due to establish a water supply to him and the remaining two firefighters to grab the engine’s two ladders, while the officer took a pre-connect 1¾-inch and quickly knocked down the fire in the stairwell using the tank water on his engine.
His crew saved 7 people over the pair of ladders, and with the fire in the stairwell contained, subsequent arriving fire crews assisted the remaining occupants outside via the stairwell.
Key study takeaways
The amount of data collected from these experiments is both fascinating and relevant, and I recommend you read the study in full. But here are some key elements I took from the study:
- Tactics such as door control, horizontal ventilation, PPV and hydraulic ventilation used immediately after suppression (water on the fire) and/or knockdown limits the gas flow into the common stairwell.
- Hydraulic ventilation, once the fire is knocked down, is almost as effective as PPV, especially if short on fire personnel.
- Ventilation before suppression (water on the fire) remains a bad practice, allowing a quicker fire growth at a time when suppression crews may be having difficulty gaining access or having equipment issues that delay them from extinguishing the fire.
- While both interior and exterior fire suppression decreases temperatures and gas concentration where occupants may be remotely located, an initial exterior fire attack when fire is showing out a door or window was shown to lower the potential hazard for firefighter entry to the involved apartment and to the potential exposure of both victims and firefighters in the enclosed common stairway, with the lowering of temperatures and hazardous gas concentrations.
- When a fire has self-vented, and especially with limited personnel, a transitional exterior attack should be utilized to limit the extension of the fire to other areas and to knock down the fire at its origin.
- The study used a straight stream, regardless of nozzle type, in an “O” pattern while also using the “flow and move” technique. Exterior lines used a straight stream to knock down any external extension, such as autoclaving to a floor above or to the soffit, then used the “O” pattern at a sharp angle to hit the ceiling of the apartment of origin through an exterior window or door.
- In an interior attack, the straight stream was again used in an “O” pattern with the “flow and move” technique. That is, the nozzle was not shut down (continuous flow) until the fire was completely knocked down. However, to avoid excessive water use, the nozzle flow could be controlled at the bale and for smaller fires at half bale when entering the apartment or room of origin.
Take some time to read
While this UL research study itself was not designed to evaluate fire tactics other than the coordination of suppression and ventilation, I believe it is certainly worth the time to read and evaluate its use in conjunction with your department’s standard operating guidelines.