Skip to content
Upcoming courses

Firefighting: Difference between revisions

Tools
From Fire Safety Academy Wiki
← Older editNewer edit →
VisualWikitext
Sanne (talk | contribs)
Bots
337 edits
Add diagrams fse-firefighting-v1.svg, fse-firefighting-v2.svg, fse-firefighting-v3.svg (level-1 visual plan)
Mark (talk | contribs)
Bots
284 edits
Revise against the FSE wiki writing guidelines: verified and corrected citations, country labels, See also, links, style (revised by Claude Opus 5.5)
Line 1: Line 1:
'''Firefighting''' is the work of controlling and extinguishing fires and carrying out related rescue and protection activities. It includes manual suppression with portable equipment and hoses, operation of fixed systems, and the access, water supply and information needed to use them. The objective can be extinguishment, control, exposure protection or support for safe evacuation.<ref name="NUREG-F25">U.S. Nuclear Regulatory Commission (2005), pp. F-25–F-26.</ref><ref name="CVM2-53">Ministry of Business, Innovation and Employment (2025), p. 53.</ref>
'''Firefighting''' is the work of controlling and extinguishing fires, together with the rescue and protection tasks that go with it. A glossary published by the US Nuclear Regulatory Commission treats it as fire suppression, either manual, with hoses, portable extinguishers or manually operated fixed systems, or automatic, by systems using water, Halon or carbon dioxide.<ref name="NUREG-F29">Iqbal and Salley (2004), p. F-29.</ref> Besides attacking the fire, fire services search for and rescue occupants, protect property and limit harm to the environment.<ref name="IFEG-2.9-3">National Research Council of Canada et al. (2005), p. 2.9-3.</ref> Early action matters: an automatic extinguishing system generally intervenes while the fire is still in its growth stage, so the fire cannot become fully developed.<ref name="VR-4.11">Van Rossum (2027), §4.11.</ref> A fire service that arrives after flashover, by contrast, may have no effect on the fire itself.<ref name="IFEG-1.9-7">National Research Council of Canada et al. (2005), p. 1.9-7.</ref> Tactics differ between countries and situations; the Dutch fire service, for example, prefers to fight building fires from outside and attacks from inside only when an exterior attack fails and this can be done safely.<ref name="NIPV-43">Van der Graaf et al. (2021/2023), p. 43.</ref>


Firefighting can be performed by building occupants, trained on-site personnel or the fire service, depending on the situation and jurisdiction. It changes the fire and its environment, but it also exposes people to heat, smoke, structural damage and changing ventilation conditions. Operational decisions must therefore account for the actual incident rather than a generic attack sequence.<ref name="Bryan-3-318">Bryan (2002), pp. 3-318–3-319.</ref><ref name="CVM2-53" />
== Who fights fires and what they aim for ==


Effective firefighting depends on a complete chain: detection, suitable agent, access, delivery and continued suppression. Extinguishing visible flame is not always proof of safety because hot fuel and deep-seated combustion can remain. Re-ignition, water supply, secondary agent hazards and firefighter egress must be considered.<ref name="NUREG-B44">U.S. Nuclear Regulatory Commission (2005), pp. B-43–B-44.</ref><ref name="CVM2-53" />
Many fires are fought first by the people who discover them. In the decision process that Bryan describes, an occupant who has recognised a fire chooses between flight, leaving the building, and fight, fetching an extinguisher or raising the alarm.<ref name="Bryan-3-318">Bryan (2002), p. 3-318.</ref> In a British study of 2,193 people at 952 fires, 14.9 % made fighting the fire their first action. In a US study of residential fires the share was 10.4 %, and in both studies men were more often active in fighting the fire.<ref name="Bryan-3-322">Bryan (2002), pp. 3-322–3-323.</ref> The Australian handbook to the Fire Safety Verification Method (print version 1.1, 2020) notes that many smouldering and small flaming fires are dealt with by occupants and never reported. Estimates of how often design fires occur are therefore commonly based on reported fires, ignoring suppression by occupants.<ref name="ABCBH-61">Australian Building Codes Board (2020b), pp. 61–62.</ref>


== Objectives and incident assessment ==
At industrial sites, trained staff and private fire brigades take part as well. The US glossary describes a fire watch: people trained to recognise fire hazards, to use fire extinguishers and to follow the proper notification procedures.<ref name="NUREG-F29" /> At US nuclear power plants, the fire brigade operates fixed systems by hand, removes fuel sources, switches off electrical systems and uses portable extinguishers and hose streams.<ref name="Nowlen-P5">Nowlen et al. (2005b), p. P-5.</ref> The International Fire Engineering Guidelines (2005 edition) include such private brigades, for example the brigade of an industrial complex, in their analysis of fire service intervention.<ref name="IFEG-1.9-1">National Research Council of Canada et al. (2005), p. 1.9-1.</ref>


The incident objective determines how performance should be judged. A small fire may be extinguished, while a larger fire may need to be controlled to prevent spread or protect escape routes. Exposure protection can also be valuable even where the initial fuel continues to burn.<ref name="Fleming-4-72">Fleming (2002), p. 4-72.</ref><ref name="NUREG-B15">U.S. Nuclear Regulatory Commission (2005), p. B-15.</ref>
The aims of firefighting go beyond putting out flames. According to the guidelines, fire services are commonly responsible for search and rescue, containing and extinguishing the fire and protecting property. They also protect the environment and the community, for example from contaminated firefighting water running off a chemical warehouse.<ref name="IFEG-2.9-3" /> Control means that the fire is kept from growing, for instance by wetting nearby combustibles and cooling the hot gases under the ceiling, while extinguishment is the complete suppression of all burning material.<ref name="NUREG-F25">Iqbal and Salley (2004), p. F-25.</ref> An attack can be offensive, applying water to the fire, or defensive, using hose streams to protect adjoining property, or both.<ref name="IFEG-1.9-4">National Research Council of Canada et al. (2005), p. 1.9-4.</ref>


Assessment begins with fuel, form, location and development. A solid deep-seated fire, a liquid pool and a pressurised spray require different delivery methods. Building geometry and ventilation can change smoke movement, fire intensity and access to the burning region.<ref name="Scheffey-4-88">Scheffey (2002), p. 4-88.</ref><ref name="IFEG-2-5-6">Australian Building Codes Board et al. (2005), p. 2.5-6.</ref>
== How fires are put out ==


The initial fire stage is different from a fully developed enclosure fire. Van Rossum distinguishes local development from a compartment fire whose conditions are often ventilation controlled. Firefighting assessment must identify which conditions exist at the time of intervention.<ref name="VR-4-11">Van Rossum (2027), §4.11.</ref><ref name="CVM2-54">Ministry of Business, Innovation and Employment (2025), pp. 54–55.</ref>
[[Extinguishing mechanisms]] work by separating the fuel from the flame, removing or diluting the oxygen, cooling the fuel or the flame, or interfering with the chemistry of combustion. Several of them often act at once. Water on a burning solid cools the solid, so that it releases less flammable gas, and cools the flame, so that less heat reaches the fuel. Steam can keep oxygen away in some confined conditions, and a fog of fine droplets can block heat radiation.<ref name="NUREG-B15">Iqbal and Salley (2004), p. B-15.</ref> Water is the most common extinguishing agent because it is widely available, cheap and able to absorb a great deal of heat. Fleming gives about 2,590 kJ per US gallon heated from 21 °C and turned into steam, or roughly 680 kJ per litre.<ref name="Fleming-4-72">Fleming (2002), p. 4-72.</ref>
[[File:fse-firefighting-v1.svg|thumb|upright=1.5|alt=Control, extinction and exposure protection are supported by cooling, blanketing and chemical action.|Firefighting objectives and mechanisms must match the incident. Based on Iqbal and Salley (2004), p. B-15 and Fleming (2002), p. 4-72.]]


A localised fire can spread to other objects before suppression arrives. The assessment must include heat transfer and exposure to nearby fuel, not only the first item. Water cooling or another suitable agent can protect those exposed materials and reduce spread.<ref name="Fleming-4-72" /><ref name="NUREG-B15" />
Water does not suit every fire. It is inappropriate for certain water-reactive materials, with which it can produce heat, flammable or toxic gases or explosions. Most hydrocarbon fuels are lighter than water and do not mix with it, so they float on the water and keep burning.<ref name="Fleming-4-72" /> On hot oil or fat, water can sink below the surface, turn to steam and throw out burning oil in a boilover.<ref name="NUREG-B58">Iqbal and Salley (2004), p. B-58.</ref> In the US classification of fires, water must never be used on Class D fires, which involve combustible metals such as magnesium, sodium and lithium.<ref name="NUREG-B16">Iqbal and Salley (2004), p. B-16.</ref>


Firefighting also includes rescue and protection of the responders' egress. C/VM2 requires access to the fire floor, search of the general area and protection of the way out. These tasks cannot be evaluated only by water flow or agent quantity.<ref name="CVM2-53" />
Foam is the main alternative to water, used mostly on burning liquids.<ref name="NUREG-B58" /> Firefighting foam consists of air-filled bubbles made from water mixed with a foam concentrate, typically at 1, 3 or 6 percent. It floats on the fuel and forms a layer that keeps air out and stops the fuel from evaporating, so the fire goes out once the whole surface is covered. Low-expansion foam works well on a pool of liquid but much less well on running fuel or a pressurised spray, where an extra agent such as dry chemical is used.<ref name="Scheffey-4-88">Scheffey (2002), p. 4-88.</ref> Heat breaks foam down, so it must be applied fast enough and in large enough amounts to keep a layer over the fuel.<ref name="NUREG-B59">Iqbal and Salley (2004), p. B-59.</ref> A ruptured foam blanket can let the fire burn back and put firefighters at risk.<ref name="NUREG-B60">Iqbal and Salley (2004), p. B-60.</ref>


== Extinguishing mechanisms ==
Dry chemical powders probably act mainly on the chemistry of the flame, and they also absorb heat, block radiation and, in one type, coat the burning surface. They leave residue that needs thorough cleaning and can corrode equipment.<ref name="NUREG-B55">Iqbal and Salley (2004), pp. B-55–B-56.</ref> In a 2001 fire at the Point Beach nuclear plant in the United States, the fire brigade discharged about 32 kg of dry chemical from three extinguishers without success. The fire was finally put out with 57 to 76 L of water, and white dust covered large parts of the containment building.<ref name="NUREG-H29">Iqbal and Salley (2004), p. H-29.</ref> Gaseous agents such as Halon 1301 put out visible flames almost at once, but glowing combustion inside a solid fuel can continue and re-ignite when air is let back in.<ref name="NUREG-B43">Iqbal and Salley (2004), pp. B-43–B-44.</ref>


[[Extinguishing mechanisms]] include cooling, fuel separation, oxygen removal or dilution, and chemical interference with combustion. Real agents often use several mechanisms together. Their effectiveness depends on reaching and remaining at the burning region in a suitable form.<ref name="NUREG-B15" />
== Manual firefighting: extinguishers, hoses and water ==
[[File:fse-firefighting-v1.svg|thumb|upright=1.5|alt=Control, extinction and exposure protection are supported by cooling, blanketing and chemical action.|Firefighting objectives and mechanisms must match the incident. Based on U.S. Nuclear Regulatory Commission (2005), p. B-15 and Fleming (2002), p. 4-72.]]


Water absorbs heat from fuel and flame and reduces pyrolysis and heat feedback. Steam can contribute to oxygen displacement in some confined conditions, and water fog can attenuate radiation. Water is nevertheless unsuitable for some reactive materials and does not form a blanket over lighter, immiscible liquids.<ref name="NUREG-B15" /><ref name="Fleming-4-72" />
A [[Fire extinguisher]] is one of the means of manual suppression named in the US glossary, alongside hoses and manually operated fixed systems.<ref name="NUREG-F29" /> In the United States, its rating combines a number for relative effectiveness with a letter for each class of fire on which it has proved effective.<ref name="NUREG-F25" /> Class A covers ordinary combustibles such as wood and paper, B flammable liquids and gases, and C fires involving energised electrical equipment. Class D covers combustible metals and K cooking oils and fats.<ref name="NUREG-B16" /> Dry chemical agents are safe on electrical fires as far as electric shock is concerned, but they can damage delicate equipment.<ref name="NUREG-B55" />


Foam can cover a suitable liquid surface, reduce vapour release and limit radiant heating. It must spread and remain coherent despite heat, drainage and mechanical disruption. Running fuel and pressurised spray do not provide the same surface as a pool.<ref name="Scheffey-4-88" /><ref name="NUREG-B59">U.S. Nuclear Regulatory Commission (2005), pp. B-58–B-59.</ref>
Hose lines need a water supply that the fire service can reach. A [[Fire hydrant]] provides water to the pumpers of the fire department.<ref name="NUREG-F26">Iqbal and Salley (2004), p. F-26.</ref> In tall buildings, [[Dry and wet risers]] carry water to outlets on the floors, so firefighters can connect their hoses near the fire instead of laying them from the street.<ref name="NUREG-F61">Iqbal and Salley (2004), pp. F-61–F-62.</ref><ref name="Hopkins-21">Hopkins et al. (2005), p. 21.</ref> In New York City, supplying extra water to a building's fire protection systems is a routine fire department operation.<ref name="Hopkins-xlii">Hopkins et al. (2005), p. xlii.</ref> Reaching the hydrants, inlets and fire floor is a matter of [[fire service access]], which New Zealand's Verification Method C/VM2 (second edition, 2025) covers in its scenario for firefighting operations.<ref name="CVM2-53">Ministry of Business, Innovation and Employment (2025b), p. 53.</ref>


Dry chemicals can inhibit flame chemistry, cool, coat and block radiation. They can also create residue, corrosion and reduced visibility. Gaseous agents can reduce oxygen or affect flame chemistry but require retention and attention to deep-seated combustion.<ref name="NUREG-B56">U.S. Nuclear Regulatory Commission (2005), pp. B-55–B-56.</ref><ref name="NUREG-B44" />
The water flow must match the size of the fire. The Netherlands Institute for Public Safety (NIPV) gives rules of thumb for cooling capacity. A high-pressure jet of 125 L/min is generally sufficient for a fire of up to about 2.5 MW, and a low-pressure jet of 450 L/min for up to about 10 MW.<ref name="NIPV-45">Van der Graaf et al. (2021/2023), p. 45.</ref> For comparison, Van Rossum gives about 2.5 MW for an average living-room sofa and a peak of 8.5 MW for a car.<ref name="VR-4.5">Van Rossum (2027), §4.5.</ref> He notes that such heat release data help the fire service judge whether a fire can still be fought with the flow its vehicle delivers at low, medium or high pressure.<ref name="VR-8.6">Van Rossum (2027), §8.6.</ref>


Suppression can reduce heat release without immediately removing every flame. Control and extinction should therefore be distinguished. Post-discharge inspection must consider whether remaining fuel can support renewed burning after air returns or the blanket is disrupted.<ref name="Fleming-4-72" /><ref name="NUREG-B44" />
Time is often decisive. In an aircraft fuel spill fire, the aluminium skin of the aircraft can burn through in about 1 minute. The cabin becomes unsurvivable once the windows melt out after about 3 minutes.<ref name="Scheffey-4-103">Scheffey (2002), p. 4-103.</ref> Airport rescue and firefighting vehicles are designed to reach an incident on the airport within 2 to 3 minutes. Once there, they must apply agent to control the fire within 1 minute, a critical time recognised by US and international aviation and fire protection bodies.<ref name="Scheffey-4-103" />


== Portable and manual suppression ==
== Automatic systems and the fire service ==


A [[Fire extinguisher]] provides a limited quantity of agent for manual application. Its label and tested use identify the intended fire types, but delivery and fire geometry still determine the outcome. Repeated discharge can also increase contamination and visibility problems without ensuring extinction.<ref name="NUREG-B16">U.S. Nuclear Regulatory Commission (2005), p. B-16.</ref><ref name="NUREG-H29">U.S. Nuclear Regulatory Commission (2005), pp. H-28–H-29.</ref>
Automatic sprinklers often act long before firefighters can. Human response, from discovery of the fire to the travel of the fire brigade, usually takes much longer than the time sprinklers need to control a fire in its early stages. Sprinklers are designed to control a fire, but they often put it out, because the wetted materials around it can no longer heat up to their ignition temperature.<ref name="NUREG-10-1">Iqbal and Salley (2004), pp. 10-1–10-2.</ref> Even where sprinklers do not suppress a fire, their cooling can protect the structure until the fire is extinguished by other means.<ref name="Fleming-4-72" />


Manual suppression requires appropriate training and notification. NUREG's fire-watch description links extinguisher use with hazard recognition and proper notification procedures. Personnel must understand both the agent's intended purpose and its secondary effects.<ref name="NUREG-F29">U.S. Nuclear Regulatory Commission (2005), p. F-29.</ref>
Manual and automatic firefighting both depend on the water supply. Sprinkler systems fail when a supply valve is closed, a water tank is empty, a fire pump does not start or loses its power, or the pipes and heads are blocked or corroded.<ref name="NUREG-10-2">Iqbal and Salley (2004), p. 10-2.</ref> At World Trade Center 7, the sprinklers on the lower 20 floors depended on one automatic fire pump and on the city main.<ref name="Hopkins-xli">Hopkins et al. (2005), p. xli.</ref> After the collapse of WTC 1, the fire department could not provide firefighting or supplementary water to the building.<ref name="Hopkins-xliv">Hopkins et al. (2005), p. xliv.</ref> In the SFPE Handbook, Siu warns that many fire risk studies for nuclear power plants ignore the reliance of automatic and manual suppression on a common water supply, which can make their results non-conservative.<ref name="Siu-5-221">Siu (2002), p. 5-221.</ref>
[[File:fse-firefighting-v2.svg|thumb|upright=1.5|alt=Extinguisher, hydrant and hose line, and automatic sprinkler have different operating chains.|Manual and automatic suppression have different dependencies. Based on Iqbal and Salley (2004), pp. F-25–F-26 and 10-1–10-2.]]


Bryan describes occupants choosing between fighting, fleeing, seeking refuge and warning others. A manual attack can be well intended but inappropriate if the fire is more developed or the agent is unsuitable. The response should be reassessed as information and conditions change.<ref name="Bryan-3-318" /><ref name="Bryan-3-319">Bryan (2002), p. 3-319.</ref>
Risk studies of US nuclear power plants estimate from past events how long manual firefighting takes. For all fire types together, NUREG/CR-6850 (2005) gives a probability of 0.46 that a fire is still burning after 10 minutes of manual suppression, and 0.10 after 30 minutes.<ref name="Nowlen-P9">Nowlen et al. (2005b), pp. P-9–P-10.</ref> These curves leave out the time to detect the fire and the response time of the fire brigade. Both must be subtracted from the time before damage occurs to find the time that is actually available for suppression.<ref name="Nowlen-P9" />


Portable equipment is not a substitute for developed-fire resources. Fire service access, pumping appliances, hoses and sustained water supplies may be needed as the incident grows. The threshold for safe and effective manual action must be part of the operational plan rather than assumed.<ref name="CVM2-53" /><ref name="NUREG-F25" />
== Tactics: inside or outside, offensive or defensive ==


Post-use conditions include residue, impaired visibility and possible reflash. NUREG's Point Beach example reports repeated dry-chemical use before water finally extinguished the fire, with residue spread over equipment and surfaces. That case illustrates why delivery and cleanup are part of suppression performance.<ref name="NUREG-H29" />
Firefighting tactics weigh the chance of success against the risk to firefighters. The International Fire Engineering Guidelines note that a shortage of water or of firefighters for an interior attack can change the strategy from offensive, fighting the fire, to defensive. The defensive aim is to stop the fire spreading to adjoining buildings.<ref name="IFEG-2.9-4">National Research Council of Canada et al. (2005), p. 2.9-4.</ref>


== Fixed systems and water supplies ==
The Dutch fire service arranges its tactics in a quadrant model. The goal is either to prevent fire growth or to extinguish the seat of the fire, and the attack is made either from inside or from outside the building. Firefighters prefer to fight a fire from outside, and they carry out an interior attack only in a small room or building when an exterior attack fails and it can be done safely. A smoke-filled space is entered only if the benefits outweigh the risks, and reducing material damage is not a reason to take risks.<ref name="NIPV-43" />


Automatic systems can begin controlling a fire before personnel arrive. Sprinklers detect heat at individual heads and distribute water over the protected area. Wet, dry, deluge and preaction arrangements introduce different activation and delivery sequences.<ref name="NUREG-10-1">U.S. Nuclear Regulatory Commission (2005), pp. 10-1–10-2.</ref><ref name="Fleming-4-73">Fleming (2002), p. 4-73.</ref>
The Dutch basic principles start with taking time to stop and think, followed by a reconnaissance from outside, for example with a thermal imaging camera. Three questions then decide the type of attack: is it known where the fire is, can it be reached from outside, and is there enough cooling capacity.<ref name="NIPV-44">Van der Graaf et al. (2021/2023), p. 44.</ref> If the fire cannot be found, reached and cooled from outside, large buildings are fought defensively and considered beyond saving.<ref name="NIPV-44" /> In a small building an offensive interior attack may still be possible, with control of the doors, the building kept closed where possible and water on the fire as quickly as possible.<ref name="NIPV-63">Van der Graaf et al. (2021/2023), p. 63.</ref>


A [[Fire hydrant]] supplies water to a pumping appliance, which then delivers it through hoses. The source, connection, pump and hose route must all remain available. The hydrant itself is not a complete extinguishing system.<ref name="NUREG-F25" />
An interior attack also needs a short route through smoke and enough cooling capacity, and the commanding officer on site makes the final decision.<ref name="NIPV-45" /> Van Rossum stresses the same point for engineering studies: a positive result does not mean that the fire service will attack from inside, because that decision always rests with the fire service on site.<ref name="VR-9.3">Van Rossum (2027), §9.3 (Results from zone models).</ref> The Australian handbook, summarising limits from the Fire Brigade Intervention Model, adds that search and rescue cannot be carried out in a room that has reached flashover.<ref name="ABCBH-113">Australian Building Codes Board (2020b), p. 113.</ref>


[[Dry and wet risers]] distribute water to hose outlets inside a building. Wet risers are permanently charged, while manual standpipes rely on fire service supply. Classifications of those standpipes concern intended use and are distinct from fire-fuel classifications.<ref name="NUREG-F61">U.S. Nuclear Regulatory Commission (2005), pp. F-61–F-62.</ref>
== Ventilation, backdraft and smoke explosions ==


Water supplies can include municipal mains, reserve tanks and pumps. NIST's WTC analysis shows how those components can support sprinklers and standpipes, but it also identifies possible loss through power failure, damage or infrastructure impairment. Redundancy must be evaluated for independence.<ref name="Hopkins-xxxv">Hopkins, Schoenrock, and Budnick (2005), p. xxxv.</ref><ref name="Hopkins-xli">Hopkins, Schoenrock, and Budnick (2005), pp. xli–xlii.</ref>
Firefighters also change the ventilation of a burning building. [[Positive pressure ventilation]] uses fans to blow fresh air into an enclosure, creating a pressure difference that drives the existing air and combustion products out through an exit opening. It is used to influence the degree of ventilation, to assist firefighting and to influence the burning itself.<ref name="NUREG-F46">Iqbal and Salley (2004), p. F-46.</ref>
[[File:fse-firefighting-v2.svg|thumb|upright=1.5|alt=Extinguisher, hydrant and hose line, and automatic sprinkler have different operating chains.|Manual and automatic suppression have different dependencies. Based on U.S. Nuclear Regulatory Commission (2005), pp. F-25–F-26 and pp. 10-1–10-2.]]
[[File:fse-firefighting-v3.svg|thumb|upright=1.5|alt=Fan airflow changes smoke flow and can supply oxygen to hot unburned gases.|Ventilation can alter both visibility and combustion conditions. Based on Iqbal and Salley (2004), p. F-46 and Van Rossum (2027), §4.9.]]


Fixed systems also depend on maintenance and suitable hazards. Closed valves, blocked pipes, corroded heads and changed storage can prevent effective operation. A system designed for one commodity may not control a later, different fire challenge.<ref name="NUREG-10-2">U.S. Nuclear Regulatory Commission (2005), p. 10-2.</ref><ref name="Fleming-4-73" />
Adding air is risky when a fire is short of oxygen. In a ventilation-controlled fire the oxygen supply limits the burning, so unburnt pyrolysis gases can build up, and mixed with oxygen they form a flammable mixture that needs only ignition energy.<ref name="VR-4.8">Van Rossum (2027), §4.8.</ref> A [[Backdraft]] is the explosive ignition of such gases when fresh air suddenly enters, for example when a door is opened, and it can produce a large fireball or a jet of flame. Van Rossum describes it as a dangerous phenomenon for the fire service.<ref name="VR-4.9">Van Rossum (2027), §4.9.</ref>


== Access and operational information ==
A [[smoke explosion]] is a different event. It is the very rapid burning of flammable gases that are already reasonably premixed with air within their explosion limits, set off by a spark, by glowing particles or by self-ignition.<ref name="VR-4.10">Van Rossum (2027), §4.10.</ref> The Dutch basic principles favour keeping a building closed where possible, which they call anti-ventilation, and controlling the doors during an interior attack.<ref name="NIPV-63" />


[[Fire service access]] includes vehicle hard-standing, unobstructed paths to the building and connections, and safe internal routes. C/VM2 addresses those provisions together with water delivery, firefighter reach and protected egress. Arrival at the site alone does not demonstrate operational access.<ref name="CVM2-53" />
Ventilation, smoke control and sprinklers also affect one another. The NIPV study notes that smoke and heat removal can raise the chance of a successful interior attack in indoor car parks.<ref name="NIPV-6">Van der Graaf et al. (2021/2023), p. 6.</ref> Building ventilation systems that keep running during a fire, or that recirculate air, can themselves spread smoke through the building.<ref name="Evans-70">Evans et al. (2005), p. 70.</ref> Sprinkler sprays can also cool the heat-sensitive links of downstream sprinklers and smoke vents and delay their opening, effects known as sprinkler skipping and vent skipping.<ref name="Cooper-3-239">Cooper (2002b), p. 3-239.</ref>


Connection points must be accessible and understandable. Firefighters need to know which inlets, valves and zones serve the fire area. Clear information about the fire location, available systems and hazardous substances or processes is part of that access.<ref name="CVM2-53" /><ref name="Hopkins-xxxv" />
== Firefighting in building design and regulation ==


Hose routes must be practical for the building layout. C/VM2 uses approximate hose lengths in one water-delivery method, but indirect routes and fire conditions can affect actual deployment. Structural stability must support access for the required period.<ref name="CVM2-54" />
The International Fire Engineering Guidelines state that evacuation analysis should not rely on fire service intervention, although the needs of fire services must not be discounted.<ref name="IFEG-1.9-1" /> In New Zealand, C/VM2 (second edition, 2025) sets out a design scenario for firefighting operations. It sets requirements for access, water supply, information for firefighters and structural stability.<ref name="CVM2-53" /> For large unsprinklered firecells near a boundary, it sets limits for the moment when firefighters first apply water. The radiation at 1.5 m above the floor may then not exceed 4.5 kW/m², and the smoke layer must be at least 2 m above the floor.<ref name="CVM2-53" /> That moment may be taken as 1,200 s, or 1,000 s with a fire alarm connected directly to a remote receiving centre.<ref name="CVM2-54">Ministry of Business, Innovation and Employment (2025b), p. 54.</ref>


The incident's fire environment affects safe operations. C/VM2 gives radiation and smoke-layer criteria for particular unsprinklered firecells when firefighters first apply water. Those are method-specific criteria and do not guarantee safe conditions for every subsequent stage.<ref name="CVM2-53" /><ref name="CVM2-54" />
In Australia, the Fire Safety Verification Method Standard 2022 includes a fire brigade intervention scenario, assessed with the Fire Brigade Intervention Model, that applies to buildings within 50 km road travel of a fire station.<ref name="FSVM-15">Australian Building Codes Board (2022), p. 15.</ref> The 2020 handbook shows how a design fire may be cut short by occupants, by sprinklers, or by fire brigade suppression before or after flashover.<ref name="ABCBH-61" /> The design fire is then modified for the automatic or fire brigade intervention that applies to the scenario.<ref name="ABCBH-61" />


Operational information should be current. Altered storage, partitions, hazards or supply arrangements can invalidate previous instructions. Building management must preserve both the physical provisions and the knowledge needed to use them.<ref name="IFEG-0-3-8">Australian Building Codes Board et al. (2005), p. 0.3-8.</ref><ref name="IFEG-1-8-14">Australian Building Codes Board et al. (2005), pp. 1.8-13–1.8-14.</ref>
In the Netherlands, an equivalent solution under the 2012 Building Decree cannot take credit for a fire service attack.<ref name="NIPV-15">Van der Graaf et al. (2021/2023), p. 15.</ref> The NIPV study stresses that the fire service has an obligation of best efforts rather than of result.<ref name="NIPV-41">Van der Graaf et al. (2021/2023), p. 41.</ref> Some Dutch design curves do include firefighting: the car fire curve in the car park standard NEN 6098, as described by Van Rossum, reflects the extinguishing action of the fire service.<ref name="VR-8.6" />


== Ventilation and backdraft ==
== Limits and common misconceptions ==


[[Positive pressure ventilation]] uses fans to blow fresh air into an enclosure, creating a pressure difference that drives combustion products through an exit opening. NUREG-1805 describes its use to influence ventilation and burning activity and to assist firefighting. The complete airflow path must be considered.<ref name="NUREG-F45">U.S. Nuclear Regulatory Commission (2005), p. F-45.</ref>
Putting out the visible flames does not always end a fire. Glowing combustion inside solids can survive a gaseous agent and re-ignite when air returns, and a damaged foam blanket can let a liquid fire burn back.<ref name="NUREG-B43" /><ref name="NUREG-B60" /> Battery packs of electric vehicles can catch fire again shortly after the flames are out. They therefore need continuous cooling and temperature monitoring, for example in a water-filled immersion container.<ref name="NIPV-46">Van der Graaf et al. (2021/2023), p. 46.</ref>
[[File:fse-firefighting-v3.svg|thumb|upright=1.5|alt=Fan airflow changes smoke flow and can supply oxygen to hot unburned gases.|Ventilation can alter both visibility and combustion conditions. Based on U.S. Nuclear Regulatory Commission (2005), p. F-45 and Van Rossum (2027), §4.9.]]


Ventilation can change visibility and smoke distribution, but it also supplies oxygen and changes pressure-driven flow. Its effect depends on the inlet, outlet, enclosure and fire condition. It should not be assumed to improve every fire scenario merely because air is moving.<ref name="NUREG-F45" /><ref name="IFEG-2-5-6" />
More agent is not automatically better. Water can spread a burning liquid that floats on it, and repeated discharges of dry chemical at Point Beach left residue across the containment building without putting the fire out.<ref name="Fleming-4-72" /><ref name="NUREG-H29" /> In enclosed spaces, dry chemical can also impair breathing and reduce visibility.<ref name="NUREG-H29" /> Firefighting itself exposes firefighters to heat, flame, smoke, explosion and structural collapse, as one of the US definitions of fire suppression states.<ref name="NUREG-F29" />


[[Backdraft]] is explosive ignition of pyrolysis gases when oxygen suddenly enters an oxygen-limited room. Combustion has consumed oxygen and left hot, unburned gases, so a new air supply can trigger rapid burning. This is a distinct hazard from simply seeing smoke leave an enclosure.<ref name="VR-4-9">Van Rossum (2027), §4.9.</ref>
Engineering models cannot promise what firefighters will find. The International Fire Engineering Guidelines note that the effect of fire service activities does not lend itself easily to quantification, so many aspects rest on qualitative judgement.<ref name="IFEG-2.9-2">National Research Council of Canada et al. (2005), p. 2.9-2.</ref> C/VM2's limits apply only at the moment firefighters first apply water, and operations after that depend on the conditions they face at the time.<ref name="CVM2-54" />
 
A [[Smoke explosion]] instead concerns rapid combustion of a reasonably premixed flammable gas cloud within explosion limits. Van Rossum distinguishes it from backdraft in the source sections. Ventilation decisions must therefore consider the mixture's history, not only the immediate visibility.<ref name="VR-4-10">Van Rossum (2027), §4.10.</ref>
 
Smoke control and firefighting ventilation can interact with sprinklers. Water sprays cool hot gases and can affect later heat-sensitive equipment, while fans change smoke paths. These interactions must be included when assessing the timing and sequence of operations.<ref name="Evans-70">Evans et al. (2005), p. 70.</ref><ref name="Cooper-3-239">Cooper (2002), p. 3-239.</ref>
 
== Management and reliability ==
 
Firefighting provisions must remain usable in the building's current condition. Routes should be clear, connections accessible, signs readable and emergency systems operational. Maintenance must preserve the complete functional chain rather than isolated components.<ref name="IFEG-1-8-14" /><ref name="NUREG-10-2" />
 
Impairments require explicit management. Closed valves, disabled detectors, pump failures and maintenance shutdowns can change the protection available during an incident. Restoration should be verified by appropriate functional checks before the original assumptions are relied upon.<ref name="NUREG-10-2" /><ref name="ABCB-130">Australian Building Codes Board (2020), pp. 129–130.</ref>
 
Training should include the intended operating sequence and its limitations. Personnel need to understand agent compatibility, access, notification, changing fire conditions and withdrawal. A drill based only on ideal conditions may not reveal failures in those arrangements.<ref name="NUREG-F29" /><ref name="Proulx-3-350">Proulx (2002), p. 3-350.</ref>
 
Common-cause failure can affect several provisions. Shared power, water supplies, detection or structural elements can disable access, suppression and information together. The assessment should identify what remains available after each relevant failure.<ref name="ABCB-131" /><ref name="CVM2-58">Ministry of Business, Innovation and Employment (2025), pp. 58–59.</ref>
 
Changes to the building or its use require re-evaluation. New fuel arrangements, partitions, storage or occupancy can alter fire growth, access and required supply. A previously effective provision may no longer match the hazard.<ref name="IFEG-0-3-8" /><ref name="NUREG-10-2" />
 
== Evaluation and common misunderstandings ==
 
Firefighting is not only the application of water. It includes agent selection, access, delivery, rescue, information and control of the fire environment. Water may be effective for one scenario and harmful or ineffective for another.<ref name="NUREG-B15" /><ref name="Fleming-4-72" />
 
Visible flame extinction is not proof of complete safety. Hot fuel, deep-seated combustion and damaged foam blankets can support renewed burning. Post-discharge inspection and retention of suitable suppression conditions are necessary.<ref name="NUREG-B44" /><ref name="NUREG-B60">U.S. Nuclear Regulatory Commission (2005), p. B-60.</ref>
 
More ventilation is not automatically better. Fans can change smoke and oxygen conditions in ways that affect fire development and backdraft risk. Inlet and outlet paths, enclosure geometry and the mixture's history must be evaluated.<ref name="NUREG-F45" /><ref name="VR-4-9" />
 
A positive engineering result does not dictate a particular fire service action. Van Rossum notes that an interior attack remains a decision for firefighters at the scene. Models can inform that decision but cannot guarantee the conditions they will face.<ref name="VR-14-2">Van Rossum (2027), §14.2.</ref>
 
The complete assessment therefore connects the incident, people, agents and building. It identifies what must operate, which failures are credible and how responders can reach and leave the fire area safely. Firefighting performance belongs to that whole operational system.<ref name="CVM2-53" /><ref name="NUREG-F25" />
 
An incident review should identify which fire conditions drive the response. A growing local fire, a ventilation-limited enclosure and a fire threatening neighbouring property require different priorities. The chosen objective should determine which people need protection, which agent is appropriate and which conditions must be controlled first.<ref name="CVM2-53" /><ref name="VR-4-11" />
 
Delivery time should be part of that review. Detection, notification, appliance travel, hose deployment and agent activation all occur before suppression can influence the fire. C/VM2's intervention times are method-specific inputs, and a separate brigade model must justify any alternative time.<ref name="CVM2-54" />
 
Protection measures can also change one another's effectiveness. Suppression can alter smoke temperature and buoyancy, ventilation can alter oxygen and pressure, and altered conditions can change detector or vent activation. The sequence should therefore be analysed as an interacting system rather than as independent actions on a checklist.<ref name="Evans-70" /><ref name="Cooper-3-239" />
 
Operational evidence should distinguish capacity from availability. A water network may have adequate design flow, but a closed valve or damaged main prevents its use. Personnel may have suitable equipment, but an obstructed or unsafe route prevents deployment. Both forms of limitation must be recorded.<ref name="Hopkins-xli" /><ref name="CVM2-53" />
 
The response record should also preserve the basis for post-incident decisions. Hot fuel, damaged boundaries, residual agents and impaired structures can remain hazardous after visible flame is reduced. Review before re-entry or continued suppression should account for those conditions and for possible renewed burning.<ref name="NUREG-B44" /><ref name="CVM2-54" />
 
A final check should test whether the chosen measures remain compatible with one another. Agent delivery must suit the fuel, access must support deployment, and ventilation must not create unacceptable conditions elsewhere. The assessment should also state which provisions are required simultaneously and which independent backups exist if one fails.<ref name="ABCB-131" /><ref name="CVM2-58" />
 
Uncertainty should remain visible in the operational record. Fire development, water availability and responder timing can differ from the model, and a calculated condition is not a guarantee of what personnel will encounter. The record should therefore identify the scenario, evidence and outstanding judgement required at the scene.<ref name="CVM2-54" /><ref name="VR-14-2" />


== See also ==
== See also ==


* [[Hose reel]]
* [[Rollover]]
* [[Electric vehicle fire]]
* [[Critical water application rate]]
* [[Critical water application rate]]
* [[Electric vehicle fire]]
* [[Rollover]]


== Notes ==
== Notes ==


<ref name="ABCB-131">Australian Building Codes Board (2020), p. 131.</ref>
<references />
<references />


== References ==
== References ==


* Australian Building Codes Board. (2020). ''Fire safety verification method data sheets'' (Version 1.1). Author.
* Australian Building Codes Board. (2020b). ''Handbook: Fire Safety Verification Method'' (Print version 1.1).
* Australian Building Codes Board, National Research Council of Canada, International Code Council, & Department of Building and Housing New Zealand. (2005). ''International fire engineering guidelines'' (2005 ed.). Australian Building Codes Board.
* Australian Building Codes Board. (2022). ''Fire Safety Verification Method Standard 2022''.
* Bryan, J. L. (2002). Behavioral response to fire and smoke. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed.). National Fire Protection Association.
* Bryan, J. L. (2002). Behavioral response to fire and smoke. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 3-315–3-341). National Fire Protection Association; Society of Fire Protection Engineers.
* Cooper, L. Y. (2002). Smoke and heat venting. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed.). National Fire Protection Association.
* Cooper, L. Y. (2002b). Smoke and heat venting. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 3-219–3-242). National Fire Protection Association; Society of Fire Protection Engineers.
* Evans, D. D., Peacock, R. D., Kuligowski, E. D., Dols, W. S., & Grosshandler, W. L. (2005). ''Active fire protection systems'' (NIST NCSTAR 1-4). National Institute of Standards and Technology.
* Evans, D. D., Peacock, R. D., Kuligowski, E. D., Dols, W. S., & Grosshandler, W. L. (2005). ''Active fire protection systems'' (NIST NCSTAR 1-4). National Institute of Standards and Technology.
* Fleming, R. P. (2002). Automatic sprinkler system calculations. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed.). National Fire Protection Association.
* Fleming, R. P. (2002). Automatic sprinkler system calculations. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 4-72–4-87). National Fire Protection Association; Society of Fire Protection Engineers.
* Hopkins, M., Schoenrock, J., & Budnick, E. (2005). ''Fire suppression systems'' (NIST NCSTAR 1-4B). National Institute of Standards and Technology.
* Hopkins, M., Schoenrock, J., & Budnick, E. (2005). ''Fire suppression systems'' (NIST NCSTAR 1-4B). National Institute of Standards and Technology.
* Ministry of Business, Innovation and Employment. (2025). ''C protection from fire: Verification method C/VM2'' (2nd ed.). New Zealand Government.
* Iqbal, N., & Salley, M. H. (2004). ''Fire Dynamics Tools (FDTs): Quantitative fire hazard analysis methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program'' (NUREG-1805). U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation.
* Proulx, G. (2002). Movement of people: The evacuation timing. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed.). National Fire Protection Association.
* Ministry of Business, Innovation and Employment. (2025b). ''Verification Method C/VM2: Framework for fire safety design'' (2nd ed.).
* Scheffey, J. L. (2002). Foam agents and AFFF system design considerations. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed.). National Fire Protection Association.
* National Research Council of Canada, International Code Council, Department of Building and Housing, & Australian Building Codes Board. (2005). ''International fire engineering guidelines'' (2005 ed.). Australian Building Codes Board.
* U.S. Nuclear Regulatory Commission. (2005). ''Fire dynamics tools: Quantitative fire hazard analysis methods for the U.S. nuclear regulatory commission fire protection inspection program'' (NUREG-1805). Author.
* Nowlen, S. P., Najafi, B., Wyant, F. J., Forester, J., Kazarians, M., Kolaczkowski, A., Joglar, F., Funk, D., Hannaman, G., & Anoba, R. (2005b). ''EPRI/NRC-RES fire PRA methodology for nuclear power facilities: Vol. 2. Detailed methodology'' (NUREG/CR-6850; EPRI 1011989). Electric Power Research Institute; U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research.
* Scheffey, J. L. (2002). Foam agents and AFFF system design considerations. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 4-88–4-122). National Fire Protection Association; Society of Fire Protection Engineers.
* Siu, N. (2002). Fire risk assessment for nuclear power plants. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 5-214–5-226). National Fire Protection Association; Society of Fire Protection Engineers.
* Van der Graaf, J., Hessels, T., & Rosmuller, N. (2023). ''Fire safety of indoor car parks accommodating electrically powered vehicles''. Nederlands Instituut Publieke Veiligheid. (Original work published 2021)
* Van Rossum, E. (2027). ''Introduction to Fire Safety Engineering''. Fire Safety Academy.
* Van Rossum, E. (2027). ''Introduction to Fire Safety Engineering''. Fire Safety Academy.


[[Category:Firefighting & Fire Service]]
[[Category:Firefighting & Fire Service]]

Revision as of 19:02, 2 November 2026

Firefighting is the work of controlling and extinguishing fires, together with the rescue and protection tasks that go with it. A glossary published by the US Nuclear Regulatory Commission treats it as fire suppression, either manual, with hoses, portable extinguishers or manually operated fixed systems, or automatic, by systems using water, Halon or carbon dioxide.[1] Besides attacking the fire, fire services search for and rescue occupants, protect property and limit harm to the environment.[2] Early action matters: an automatic extinguishing system generally intervenes while the fire is still in its growth stage, so the fire cannot become fully developed.[3] A fire service that arrives after flashover, by contrast, may have no effect on the fire itself.[4] Tactics differ between countries and situations; the Dutch fire service, for example, prefers to fight building fires from outside and attacks from inside only when an exterior attack fails and this can be done safely.[5]

Who fights fires and what they aim for

Many fires are fought first by the people who discover them. In the decision process that Bryan describes, an occupant who has recognised a fire chooses between flight, leaving the building, and fight, fetching an extinguisher or raising the alarm.[6] In a British study of 2,193 people at 952 fires, 14.9 % made fighting the fire their first action. In a US study of residential fires the share was 10.4 %, and in both studies men were more often active in fighting the fire.[7] The Australian handbook to the Fire Safety Verification Method (print version 1.1, 2020) notes that many smouldering and small flaming fires are dealt with by occupants and never reported. Estimates of how often design fires occur are therefore commonly based on reported fires, ignoring suppression by occupants.[8]

At industrial sites, trained staff and private fire brigades take part as well. The US glossary describes a fire watch: people trained to recognise fire hazards, to use fire extinguishers and to follow the proper notification procedures.[1] At US nuclear power plants, the fire brigade operates fixed systems by hand, removes fuel sources, switches off electrical systems and uses portable extinguishers and hose streams.[9] The International Fire Engineering Guidelines (2005 edition) include such private brigades, for example the brigade of an industrial complex, in their analysis of fire service intervention.[10]

The aims of firefighting go beyond putting out flames. According to the guidelines, fire services are commonly responsible for search and rescue, containing and extinguishing the fire and protecting property. They also protect the environment and the community, for example from contaminated firefighting water running off a chemical warehouse.[2] Control means that the fire is kept from growing, for instance by wetting nearby combustibles and cooling the hot gases under the ceiling, while extinguishment is the complete suppression of all burning material.[11] An attack can be offensive, applying water to the fire, or defensive, using hose streams to protect adjoining property, or both.[12]

How fires are put out

Extinguishing mechanisms work by separating the fuel from the flame, removing or diluting the oxygen, cooling the fuel or the flame, or interfering with the chemistry of combustion. Several of them often act at once. Water on a burning solid cools the solid, so that it releases less flammable gas, and cools the flame, so that less heat reaches the fuel. Steam can keep oxygen away in some confined conditions, and a fog of fine droplets can block heat radiation.[13] Water is the most common extinguishing agent because it is widely available, cheap and able to absorb a great deal of heat. Fleming gives about 2,590 kJ per US gallon heated from 21 °C and turned into steam, or roughly 680 kJ per litre.[14]

Control, extinction and exposure protection are supported by cooling, blanketing and chemical action.
Firefighting objectives and mechanisms must match the incident. Based on Iqbal and Salley (2004), p. B-15 and Fleming (2002), p. 4-72.

Water does not suit every fire. It is inappropriate for certain water-reactive materials, with which it can produce heat, flammable or toxic gases or explosions. Most hydrocarbon fuels are lighter than water and do not mix with it, so they float on the water and keep burning.[14] On hot oil or fat, water can sink below the surface, turn to steam and throw out burning oil in a boilover.[15] In the US classification of fires, water must never be used on Class D fires, which involve combustible metals such as magnesium, sodium and lithium.[16]

Foam is the main alternative to water, used mostly on burning liquids.[15] Firefighting foam consists of air-filled bubbles made from water mixed with a foam concentrate, typically at 1, 3 or 6 percent. It floats on the fuel and forms a layer that keeps air out and stops the fuel from evaporating, so the fire goes out once the whole surface is covered. Low-expansion foam works well on a pool of liquid but much less well on running fuel or a pressurised spray, where an extra agent such as dry chemical is used.[17] Heat breaks foam down, so it must be applied fast enough and in large enough amounts to keep a layer over the fuel.[18] A ruptured foam blanket can let the fire burn back and put firefighters at risk.[19]

Dry chemical powders probably act mainly on the chemistry of the flame, and they also absorb heat, block radiation and, in one type, coat the burning surface. They leave residue that needs thorough cleaning and can corrode equipment.[20] In a 2001 fire at the Point Beach nuclear plant in the United States, the fire brigade discharged about 32 kg of dry chemical from three extinguishers without success. The fire was finally put out with 57 to 76 L of water, and white dust covered large parts of the containment building.[21] Gaseous agents such as Halon 1301 put out visible flames almost at once, but glowing combustion inside a solid fuel can continue and re-ignite when air is let back in.[22]

Manual firefighting: extinguishers, hoses and water

A Fire extinguisher is one of the means of manual suppression named in the US glossary, alongside hoses and manually operated fixed systems.[1] In the United States, its rating combines a number for relative effectiveness with a letter for each class of fire on which it has proved effective.[11] Class A covers ordinary combustibles such as wood and paper, B flammable liquids and gases, and C fires involving energised electrical equipment. Class D covers combustible metals and K cooking oils and fats.[16] Dry chemical agents are safe on electrical fires as far as electric shock is concerned, but they can damage delicate equipment.[20]

Hose lines need a water supply that the fire service can reach. A Fire hydrant provides water to the pumpers of the fire department.[23] In tall buildings, Dry and wet risers carry water to outlets on the floors, so firefighters can connect their hoses near the fire instead of laying them from the street.[24][25] In New York City, supplying extra water to a building's fire protection systems is a routine fire department operation.[26] Reaching the hydrants, inlets and fire floor is a matter of fire service access, which New Zealand's Verification Method C/VM2 (second edition, 2025) covers in its scenario for firefighting operations.[27]

The water flow must match the size of the fire. The Netherlands Institute for Public Safety (NIPV) gives rules of thumb for cooling capacity. A high-pressure jet of 125 L/min is generally sufficient for a fire of up to about 2.5 MW, and a low-pressure jet of 450 L/min for up to about 10 MW.[28] For comparison, Van Rossum gives about 2.5 MW for an average living-room sofa and a peak of 8.5 MW for a car.[29] He notes that such heat release data help the fire service judge whether a fire can still be fought with the flow its vehicle delivers at low, medium or high pressure.[30]

Time is often decisive. In an aircraft fuel spill fire, the aluminium skin of the aircraft can burn through in about 1 minute. The cabin becomes unsurvivable once the windows melt out after about 3 minutes.[31] Airport rescue and firefighting vehicles are designed to reach an incident on the airport within 2 to 3 minutes. Once there, they must apply agent to control the fire within 1 minute, a critical time recognised by US and international aviation and fire protection bodies.[31]

Automatic systems and the fire service

Automatic sprinklers often act long before firefighters can. Human response, from discovery of the fire to the travel of the fire brigade, usually takes much longer than the time sprinklers need to control a fire in its early stages. Sprinklers are designed to control a fire, but they often put it out, because the wetted materials around it can no longer heat up to their ignition temperature.[32] Even where sprinklers do not suppress a fire, their cooling can protect the structure until the fire is extinguished by other means.[14]

Manual and automatic firefighting both depend on the water supply. Sprinkler systems fail when a supply valve is closed, a water tank is empty, a fire pump does not start or loses its power, or the pipes and heads are blocked or corroded.[33] At World Trade Center 7, the sprinklers on the lower 20 floors depended on one automatic fire pump and on the city main.[34] After the collapse of WTC 1, the fire department could not provide firefighting or supplementary water to the building.[35] In the SFPE Handbook, Siu warns that many fire risk studies for nuclear power plants ignore the reliance of automatic and manual suppression on a common water supply, which can make their results non-conservative.[36]

Extinguisher, hydrant and hose line, and automatic sprinkler have different operating chains.
Manual and automatic suppression have different dependencies. Based on Iqbal and Salley (2004), pp. F-25–F-26 and 10-1–10-2.

Risk studies of US nuclear power plants estimate from past events how long manual firefighting takes. For all fire types together, NUREG/CR-6850 (2005) gives a probability of 0.46 that a fire is still burning after 10 minutes of manual suppression, and 0.10 after 30 minutes.[37] These curves leave out the time to detect the fire and the response time of the fire brigade. Both must be subtracted from the time before damage occurs to find the time that is actually available for suppression.[37]

Tactics: inside or outside, offensive or defensive

Firefighting tactics weigh the chance of success against the risk to firefighters. The International Fire Engineering Guidelines note that a shortage of water or of firefighters for an interior attack can change the strategy from offensive, fighting the fire, to defensive. The defensive aim is to stop the fire spreading to adjoining buildings.[38]

The Dutch fire service arranges its tactics in a quadrant model. The goal is either to prevent fire growth or to extinguish the seat of the fire, and the attack is made either from inside or from outside the building. Firefighters prefer to fight a fire from outside, and they carry out an interior attack only in a small room or building when an exterior attack fails and it can be done safely. A smoke-filled space is entered only if the benefits outweigh the risks, and reducing material damage is not a reason to take risks.[5]

The Dutch basic principles start with taking time to stop and think, followed by a reconnaissance from outside, for example with a thermal imaging camera. Three questions then decide the type of attack: is it known where the fire is, can it be reached from outside, and is there enough cooling capacity.[39] If the fire cannot be found, reached and cooled from outside, large buildings are fought defensively and considered beyond saving.[39] In a small building an offensive interior attack may still be possible, with control of the doors, the building kept closed where possible and water on the fire as quickly as possible.[40]

An interior attack also needs a short route through smoke and enough cooling capacity, and the commanding officer on site makes the final decision.[28] Van Rossum stresses the same point for engineering studies: a positive result does not mean that the fire service will attack from inside, because that decision always rests with the fire service on site.[41] The Australian handbook, summarising limits from the Fire Brigade Intervention Model, adds that search and rescue cannot be carried out in a room that has reached flashover.[42]

Ventilation, backdraft and smoke explosions

Firefighters also change the ventilation of a burning building. Positive pressure ventilation uses fans to blow fresh air into an enclosure, creating a pressure difference that drives the existing air and combustion products out through an exit opening. It is used to influence the degree of ventilation, to assist firefighting and to influence the burning itself.[43]

Fan airflow changes smoke flow and can supply oxygen to hot unburned gases.
Ventilation can alter both visibility and combustion conditions. Based on Iqbal and Salley (2004), p. F-46 and Van Rossum (2027), §4.9.

Adding air is risky when a fire is short of oxygen. In a ventilation-controlled fire the oxygen supply limits the burning, so unburnt pyrolysis gases can build up, and mixed with oxygen they form a flammable mixture that needs only ignition energy.[44] A Backdraft is the explosive ignition of such gases when fresh air suddenly enters, for example when a door is opened, and it can produce a large fireball or a jet of flame. Van Rossum describes it as a dangerous phenomenon for the fire service.[45]

A smoke explosion is a different event. It is the very rapid burning of flammable gases that are already reasonably premixed with air within their explosion limits, set off by a spark, by glowing particles or by self-ignition.[46] The Dutch basic principles favour keeping a building closed where possible, which they call anti-ventilation, and controlling the doors during an interior attack.[40]

Ventilation, smoke control and sprinklers also affect one another. The NIPV study notes that smoke and heat removal can raise the chance of a successful interior attack in indoor car parks.[47] Building ventilation systems that keep running during a fire, or that recirculate air, can themselves spread smoke through the building.[48] Sprinkler sprays can also cool the heat-sensitive links of downstream sprinklers and smoke vents and delay their opening, effects known as sprinkler skipping and vent skipping.[49]

Firefighting in building design and regulation

The International Fire Engineering Guidelines state that evacuation analysis should not rely on fire service intervention, although the needs of fire services must not be discounted.[10] In New Zealand, C/VM2 (second edition, 2025) sets out a design scenario for firefighting operations. It sets requirements for access, water supply, information for firefighters and structural stability.[27] For large unsprinklered firecells near a boundary, it sets limits for the moment when firefighters first apply water. The radiation at 1.5 m above the floor may then not exceed 4.5 kW/m², and the smoke layer must be at least 2 m above the floor.[27] That moment may be taken as 1,200 s, or 1,000 s with a fire alarm connected directly to a remote receiving centre.[50]

In Australia, the Fire Safety Verification Method Standard 2022 includes a fire brigade intervention scenario, assessed with the Fire Brigade Intervention Model, that applies to buildings within 50 km road travel of a fire station.[51] The 2020 handbook shows how a design fire may be cut short by occupants, by sprinklers, or by fire brigade suppression before or after flashover.[8] The design fire is then modified for the automatic or fire brigade intervention that applies to the scenario.[8]

In the Netherlands, an equivalent solution under the 2012 Building Decree cannot take credit for a fire service attack.[52] The NIPV study stresses that the fire service has an obligation of best efforts rather than of result.[53] Some Dutch design curves do include firefighting: the car fire curve in the car park standard NEN 6098, as described by Van Rossum, reflects the extinguishing action of the fire service.[30]

Limits and common misconceptions

Putting out the visible flames does not always end a fire. Glowing combustion inside solids can survive a gaseous agent and re-ignite when air returns, and a damaged foam blanket can let a liquid fire burn back.[22][19] Battery packs of electric vehicles can catch fire again shortly after the flames are out. They therefore need continuous cooling and temperature monitoring, for example in a water-filled immersion container.[54]

More agent is not automatically better. Water can spread a burning liquid that floats on it, and repeated discharges of dry chemical at Point Beach left residue across the containment building without putting the fire out.[14][21] In enclosed spaces, dry chemical can also impair breathing and reduce visibility.[21] Firefighting itself exposes firefighters to heat, flame, smoke, explosion and structural collapse, as one of the US definitions of fire suppression states.[1]

Engineering models cannot promise what firefighters will find. The International Fire Engineering Guidelines note that the effect of fire service activities does not lend itself easily to quantification, so many aspects rest on qualitative judgement.[55] C/VM2's limits apply only at the moment firefighters first apply water, and operations after that depend on the conditions they face at the time.[50]

See also

Notes

  1. ↑ 1.0 1.1 1.2 1.3 Iqbal and Salley (2004), p. F-29.
  2. ↑ 2.0 2.1 National Research Council of Canada et al. (2005), p. 2.9-3.
  3. ↑ Van Rossum (2027), §4.11.
  4. ↑ National Research Council of Canada et al. (2005), p. 1.9-7.
  5. ↑ 5.0 5.1 Van der Graaf et al. (2021/2023), p. 43.
  6. ↑ Bryan (2002), p. 3-318.
  7. ↑ Bryan (2002), pp. 3-322–3-323.
  8. ↑ 8.0 8.1 8.2 Australian Building Codes Board (2020b), pp. 61–62.
  9. ↑ Nowlen et al. (2005b), p. P-5.
  10. ↑ 10.0 10.1 National Research Council of Canada et al. (2005), p. 1.9-1.
  11. ↑ 11.0 11.1 Iqbal and Salley (2004), p. F-25.
  12. ↑ National Research Council of Canada et al. (2005), p. 1.9-4.
  13. ↑ Iqbal and Salley (2004), p. B-15.
  14. ↑ 14.0 14.1 14.2 14.3 Fleming (2002), p. 4-72.
  15. ↑ 15.0 15.1 Iqbal and Salley (2004), p. B-58.
  16. ↑ 16.0 16.1 Iqbal and Salley (2004), p. B-16.
  17. ↑ Scheffey (2002), p. 4-88.
  18. ↑ Iqbal and Salley (2004), p. B-59.
  19. ↑ 19.0 19.1 Iqbal and Salley (2004), p. B-60.
  20. ↑ 20.0 20.1 Iqbal and Salley (2004), pp. B-55–B-56.
  21. ↑ 21.0 21.1 21.2 Iqbal and Salley (2004), p. H-29.
  22. ↑ 22.0 22.1 Iqbal and Salley (2004), pp. B-43–B-44.
  23. ↑ Iqbal and Salley (2004), p. F-26.
  24. ↑ Iqbal and Salley (2004), pp. F-61–F-62.
  25. ↑ Hopkins et al. (2005), p. 21.
  26. ↑ Hopkins et al. (2005), p. xlii.
  27. ↑ 27.0 27.1 27.2 Ministry of Business, Innovation and Employment (2025b), p. 53.
  28. ↑ 28.0 28.1 Van der Graaf et al. (2021/2023), p. 45.
  29. ↑ Van Rossum (2027), §4.5.
  30. ↑ 30.0 30.1 Van Rossum (2027), §8.6.
  31. ↑ 31.0 31.1 Scheffey (2002), p. 4-103.
  32. ↑ Iqbal and Salley (2004), pp. 10-1–10-2.
  33. ↑ Iqbal and Salley (2004), p. 10-2.
  34. ↑ Hopkins et al. (2005), p. xli.
  35. ↑ Hopkins et al. (2005), p. xliv.
  36. ↑ Siu (2002), p. 5-221.
  37. ↑ 37.0 37.1 Nowlen et al. (2005b), pp. P-9–P-10.
  38. ↑ National Research Council of Canada et al. (2005), p. 2.9-4.
  39. ↑ 39.0 39.1 Van der Graaf et al. (2021/2023), p. 44.
  40. ↑ 40.0 40.1 Van der Graaf et al. (2021/2023), p. 63.
  41. ↑ Van Rossum (2027), §9.3 (Results from zone models).
  42. ↑ Australian Building Codes Board (2020b), p. 113.
  43. ↑ Iqbal and Salley (2004), p. F-46.
  44. ↑ Van Rossum (2027), §4.8.
  45. ↑ Van Rossum (2027), §4.9.
  46. ↑ Van Rossum (2027), §4.10.
  47. ↑ Van der Graaf et al. (2021/2023), p. 6.
  48. ↑ Evans et al. (2005), p. 70.
  49. ↑ Cooper (2002b), p. 3-239.
  50. ↑ 50.0 50.1 Ministry of Business, Innovation and Employment (2025b), p. 54.
  51. ↑ Australian Building Codes Board (2022), p. 15.
  52. ↑ Van der Graaf et al. (2021/2023), p. 15.
  53. ↑ Van der Graaf et al. (2021/2023), p. 41.
  54. ↑ Van der Graaf et al. (2021/2023), p. 46.
  55. ↑ National Research Council of Canada et al. (2005), p. 2.9-2.

References

  • Australian Building Codes Board. (2020b). Handbook: Fire Safety Verification Method (Print version 1.1).
  • Australian Building Codes Board. (2022). Fire Safety Verification Method Standard 2022.
  • Bryan, J. L. (2002). Behavioral response to fire and smoke. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), SFPE handbook of fire protection engineering (3rd ed., pp. 3-315–3-341). National Fire Protection Association; Society of Fire Protection Engineers.
  • Cooper, L. Y. (2002b). Smoke and heat venting. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), SFPE handbook of fire protection engineering (3rd ed., pp. 3-219–3-242). National Fire Protection Association; Society of Fire Protection Engineers.
  • Evans, D. D., Peacock, R. D., Kuligowski, E. D., Dols, W. S., & Grosshandler, W. L. (2005). Active fire protection systems (NIST NCSTAR 1-4). National Institute of Standards and Technology.
  • Fleming, R. P. (2002). Automatic sprinkler system calculations. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), SFPE handbook of fire protection engineering (3rd ed., pp. 4-72–4-87). National Fire Protection Association; Society of Fire Protection Engineers.
  • Hopkins, M., Schoenrock, J., & Budnick, E. (2005). Fire suppression systems (NIST NCSTAR 1-4B). National Institute of Standards and Technology.
  • Iqbal, N., & Salley, M. H. (2004). Fire Dynamics Tools (FDTs): Quantitative fire hazard analysis methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program (NUREG-1805). U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation.
  • Ministry of Business, Innovation and Employment. (2025b). Verification Method C/VM2: Framework for fire safety design (2nd ed.).
  • National Research Council of Canada, International Code Council, Department of Building and Housing, & Australian Building Codes Board. (2005). International fire engineering guidelines (2005 ed.). Australian Building Codes Board.
  • Nowlen, S. P., Najafi, B., Wyant, F. J., Forester, J., Kazarians, M., Kolaczkowski, A., Joglar, F., Funk, D., Hannaman, G., & Anoba, R. (2005b). EPRI/NRC-RES fire PRA methodology for nuclear power facilities: Vol. 2. Detailed methodology (NUREG/CR-6850; EPRI 1011989). Electric Power Research Institute; U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research.
  • Scheffey, J. L. (2002). Foam agents and AFFF system design considerations. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), SFPE handbook of fire protection engineering (3rd ed., pp. 4-88–4-122). National Fire Protection Association; Society of Fire Protection Engineers.
  • Siu, N. (2002). Fire risk assessment for nuclear power plants. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), SFPE handbook of fire protection engineering (3rd ed., pp. 5-214–5-226). National Fire Protection Association; Society of Fire Protection Engineers.
  • Van der Graaf, J., Hessels, T., & Rosmuller, N. (2023). Fire safety of indoor car parks accommodating electrically powered vehicles. Nederlands Instituut Publieke Veiligheid. (Original work published 2021)
  • Van Rossum, E. (2027). Introduction to Fire Safety Engineering. Fire Safety Academy.
Retrieved from "https://fire-safety.academy/w/index.php?title=Firefighting&oldid=2730"