3D Firefighting – Training – Techniques


3D Firefighting – Training – Techniques – Tactics by Paul Grimwood Firetactics.com
3D Firefighting – Training – Techniques – Tactics..... The use of water-fog, or fine sprays, as opposed to the solid straight stream attack in structural fire situations is nothing new. In fact, there has been an ongoing debate for the past fifty years as to which is the best form of attack. Even quite recently, there have been research projects that lasted several years to measure the effectiveness of water-fog patterns in cooling fire gases and extinguishing fires under various ventilation parameters, in comparison to the benefits and extinguishing capabilities of straight streams. In real terms, either form of attack has advantages over the other, depending on varying conditions. However, the use of three-dimensional (3D) (also termed 'offensive) water-fog techniques during gaseous-phase suppression of structural fires is a most recent and innovative approach and the reader should be clear that such applications are used - not (solely) to extinguish fires - but mainly to make 'safe' the approach route to the fire and reduce the likelihood of fire gas ignitions - flashovers - backdrafts etc. Neither are these techniques designed to replace the 'direct' style of fire attack utilising water in a straight stream setting but moreover, to complement existing forms of fire attack in an effort to increase the safety and effectiveness of firefighting teams. The history of the three-dimensional approach began in Germany in the 1950s but failed to progress beyond theory until the 1980s, when Stockholm firefighters (under Anders Lauren) began to experiment with the techniques following a major flashover where firefighters were killed. Two Swedish engineers (Rosander & Giselson) further fuelled the debate by advancing theories that supported the tactical use of water-fog to counter the hazards associated with flashovers, backdrafts and smoke gas explosions. By 1984 the techniques were being used at real fires by firefighters in London and throughout Sweden with amazing success. This development progressed through into the 1990s where the techniques were officially adopted by fire authorities in the UK, Australia, Spain and by the US Navy for firefighting onboard ships. By the year 2000 this innovative tactical approach was also being reviewed in the USA, Holland, Germany and France. The term 'three-dimensional water-fog' is not to be confused with that of 'indirect water-fog' and the associated applications of either style are completely different. Quite simply, the 'indirect' approach is where water is applied in a fine spray form onto the heated surfaces of a fire involved compartment, or room, to create steam. This massive expansion of steam creates a positive pressure within the room and smothers the fire to extinction within seconds. However, the steam will create a sudden rise in compartmental temperature and cause a major problem for firefighters occupying the compartment. The 'three-dimensional' approach, when used as a firefighting tool, places the water-fog directly into the heated fire gases and avoids excessive contact with hot surfaces. This, in effect, causes a negative pressure within the fire compartment and firefighters are not burned by steam expansion. This effect is achieved by resorting to specific 'pulsing' techniques at the nozzle and by selecting ideal fog 'cone' angles and pattern diameters. The application is precise and requires both equipment and nozzles that are able to function with optimum effect and firefighters that fully understand and are trained in the application techniques. Three-dimensional tactics may be either defensive or offensive - the true qualities of 3 dimensional water-fog applications are realized in flashover & backdraft prevention (defensive). The 'pulsing' of water-fog into the overhead on the approach route using short rapid bursts at the nozzle serves to 'inert' the fire gas layers and will prevent or mitigate the potential for any ignition of the fire gases that may lead to such a major event. Such ignitions of accumulated fire gases may vary in their explosive force but it has been demonstrated that fine water droplets are able to offer a 'quenching' effect under such conditions and lessen the explosive effects. However, again the applications are precise and dependent on equipment, firefighter awareness and training. There are many ill-informed arguments mounted against the tactical use of three-dimensional water-fog, for example - The stream from a smooth-bore nozzle can be used just as effectively to 'cool' gases in the overhead by utilising a 'Z' pattern. It has been scientifically proven in several independent research studies that fine water droplets WILL cool gases in the overhead far more effectively than a straight stream application. The US Navy tests clearly demonstrated this fact under strict scientific monitoring. The application of water-fog causes steam burns to firefighters and pushes fire ahead of the stream. This will not happen where a 'pulsing' action is used at the nozzle, using short rapid bursts to place about a 'cup-full' of water into the overhead with each brief 'pulse'. The water will then evaporate in the gases and not on super-heated surfaces such as walls and ceiling. This cooling effect causes the gases to CONTRACT and move away from the nozzle operator. The compartmental pressure is more negative than positive and steam production is 'dry' as opposed to cloudy 'wet'. There is not enough 'force' from the 'pulses' to push fire ahead of the 'stream'. The use of water-fog upsets the thermal balance. The actual effect where three-dimensional applications are used is exactly the opposite! The smoke layering is maintained and visibility is optimised by 'pulsing' water-fog into the overhead. This has constantly been demonstrated in scientific studies, including the US Navy tests, when compared to the stream from a smooth-bore nozzle. The flow-rate required for gas-phase cooling is dangerously low. But with a select-a-flow combination nozzle you have higher flows immediately available at the flick of a switch! Gas cooling can also be effected with high-flow automatic nozzles. You have to adjust your applications to suit the equipment and flow-rates you normally work with. This is a simple training issue. Water-Fog tactics are optimised in non-ventilated spaces. This is not true of three-dimensional water-fog applications, which are effective in both ventilated and non-ventilated compartments. The 'pulsing' actions at the nozzle may create dangerous water-hammer effects. The views of major fire pump manufacturers suggest that there is no danger of causing damage to fire pumps by using 'pulsing' actions at the nozzle. Since introducing these techniques in Sweden, the UK and Australia there has been no noticeable increase in pump/nozzle maintenance/repairs although there has been some problems with bursting hosereels (booster lines) when 'pulsed' at 500 psi pump pressures. This problem has now been resolved. There are engineering solutions available in terms of pressure relief valves and hydraulic retarders that can be fitted to pumps and nozzles where any concern exists. The 'tactical solutions' and training implications associated with applying water to control environmental conditions within a fire compartment/structure go way beyond nozzle techniques. The training concepts create a greater awareness of fire growth and development; fire behaviour patterns; formations and behaviour of flammable fire gas layers; environmental and tactical risk assessment; the effects of compartmental geometry and layout; and, the tactical approach to varying situations including opening & entry procedures and the effects of tactical venting actions. This style of approach is being adopted worldwide and cites firefighter safety as the prime concern. Firefighters in NSW Fire Brigades, Australia, demonstrating nozzle 'pulsing' techniques - To view videos and further pictures DEFINITIONS 3D Offensive Fog Attack (Gas Cooling) - Defined as an application of water-fog discharged in short controlled bursts (pulses) where the water droplet range is critical. The objective (defensive use) is to suspend the droplets into the fire gas layers to cool, inert and dilute them, bringing them outside their immediate range of flammability in an attempt to prevent or quench subsequent ignitions. This form of application may also be used to knock-down fire-gas formations (offensive use) that are burning off inside a compartment under a ventilation controlled regime (where the amount of fire gases burning off inside the compartment is dictated by the quantity of oxygen/air entering through ventilation openings. The applications are made on a three-dimensional basis into a cubic volume of fire gases inside an enclosure (compartment or room) and the strategy is offensive - with firefighters occupying the compartment at the time of attack. This application of water-fog may be utilised both inside vented and un-vented compartments. The calculations used to quantify effect are based upon volumetric suspension (Cu. Metres etc). Indirect (Defensive) Water-fog Attack - COMBINATION ATTACK - Defined as an application of a water-fog (or spray) where the droplet range is not so critical, the objective being to apply the water (usually from the exterior, arguably in a defensive mode) so that the droplets reach super-heated surfaces including the walls and ceiling. This creates a massive amount of hot wet steam that smothers the flames, sometimes to extinction. The calculations involved in this style of application are based upon area drenched (Sq.metres etc). Such applications are often used to great effect when backdraft conditions are prevalent. Direct Attack - Made directly at the base of the fire-plume to reach the source of the flames, using either a smooth-bore nozzle or straight-stream or narrowed fog pattern from a combination nozzle. This attack may be either offensive or defensive, depending upon the level of fire spread involved. ALL THREE FORMS OF FIRE ATTACK HAVE A PLACE ON THE MODERN FIREGROUND UNDER VARYING CONDITIONS ‘3D Firefighting’ – Oklahoma State University FPP/IFSTA 2005 by Paul Grimwood; Ed Hartin; John McDonough; and Shan Raffel
About the author: Paul GRIMWOOD (Website originator in 1999) of Firetactics.com Served 26 years as a professional firefighter, mostly within the busy inner-city area of London's west-end. He has also served in the West Midlands and Merseyside Brigades as well as lengthy study detachments to the fire departments of New York City, Boston, Chicago, Los Angeles, San Francisco, Las Vegas, Phoenix, Miami, Dallas, Metro Dade Florida, Seattle, Paris, Valencia, Stockholm and Amsterdam. During the mid 1970s he served as a Long Island volunteer firefighter in New York State USA. He has four books in six languages and over 100 technical papers on firefighting strategy published. He can be contacted at Fire4242@aol.com

3D Firefighting – Training – Techniques – Tactics
by Paul Grimwood
Firetactics.com

3D Firefighting – Training – Techniques – Tactics.....

The use of water-fog, or fine sprays, as opposed to the solid straight stream attack in structural fire situations is nothing new. In fact, there has been an ongoing debate for the past fifty years as to which is the best form of attack. Even quite recently, there have been research projects that lasted several years to measure the effectiveness of water-fog patterns in cooling fire gases and extinguishing fires under various ventilation parameters, in comparison to the benefits and extinguishing capabilities of straight streams. In real terms, either form of attack has advantages over the other, depending on varying conditions.

However, the use of three-dimensional (3D) (also termed 'offensive) water-fog techniques during gaseous-phase suppression of structural fires is a most recent and innovative approach and the reader should be clear that such applications are used - not (solely) to extinguish fires - but mainly to make 'safe' the approach route to the fire and reduce the likelihood of fire gas ignitions - flashovers - backdrafts etc. Neither are these techniques designed to replace the 'direct' style of fire attack utilising water in a straight stream setting but moreover, to complement existing forms of fire attack in an effort to increase the safety and effectiveness of firefighting teams.

The history of the three-dimensional approach began in Germany in the 1950s but failed to progress beyond theory until the 1980s, when Stockholm firefighters (under Anders Lauren) began to experiment with the techniques following a major flashover where firefighters were killed. Two Swedish engineers (Rosander & Giselson) further fuelled the debate by advancing theories that supported the tactical use of water-fog to counter the hazards associated with flashovers, backdrafts and smoke gas explosions. By 1984 the techniques were being used at real fires by firefighters in London and throughout Sweden with amazing success. This development progressed through into the 1990s where the techniques were officially adopted by fire authorities in the UK, Australia, Spain and by the US Navy for firefighting onboard ships. By the year 2000 this innovative tactical approach was also being reviewed in the USA, Holland, Germany and France.

The term 'three-dimensional water-fog' is not to be confused with that of 'indirect water-fog' and the associated applications of either style are completely different. Quite simply, the 'indirect' approach is where water is applied in a fine spray form onto the heated surfaces of a fire involved compartment, or room, to create steam. This massive expansion of steam creates a positive pressure within the room and smothers the fire to extinction within seconds. However, the steam will create a sudden rise in compartmental temperature and cause a major problem for firefighters occupying the compartment. The 'three-dimensional' approach, when used as a firefighting tool, places the water-fog directly into the heated fire gases and avoids excessive contact with hot surfaces. This, in effect, causes a negative pressure within the fire compartment and firefighters are not burned by steam expansion. This effect is achieved by resorting to specific 'pulsing' techniques at the nozzle and by selecting ideal fog 'cone' angles and pattern diameters. The application is precise and requires both equipment and nozzles that are able to function with optimum effect and firefighters that fully understand and are trained in the application techniques.

Three-dimensional tactics may be either defensive or offensive - the true qualities of 3 dimensional water-fog applications are realized in flashover & backdraft prevention (defensive). The 'pulsing' of water-fog into the overhead on the approach route using short rapid bursts at the nozzle serves to 'inert' the fire gas layers and will prevent or mitigate the potential for any ignition of the fire gases that may lead to such a major event. Such ignitions of accumulated fire gases may vary in their explosive force but it has been demonstrated that fine water droplets are able to offer a 'quenching' effect under such conditions and lessen the explosive effects. However, again the applications are precise and dependent on equipment, firefighter awareness and training.

There are many ill-informed arguments mounted against the tactical use of three-dimensional water-fog, for example -

The stream from a smooth-bore nozzle can be used just as effectively to 'cool' gases in the overhead by utilising a 'Z' pattern. It has been scientifically proven in several independent research studies that fine water droplets WILL cool gases in the overhead far more effectively than a straight stream application. The US Navy tests clearly demonstrated this fact under strict scientific monitoring.

The application of water-fog causes steam burns to firefighters and pushes fire ahead of the stream. This will not happen where a 'pulsing' action is used at the nozzle, using short rapid bursts to place about a 'cup-full' of water into the overhead with each brief 'pulse'. The water will then evaporate in the gases and not on super-heated surfaces such as walls and ceiling. This cooling effect causes the gases to CONTRACT and move away from the nozzle operator. The compartmental pressure is more negative than positive and steam production is 'dry' as opposed to cloudy 'wet'. There is not enough 'force' from the 'pulses' to push fire ahead of the 'stream'.

The use of water-fog upsets the thermal balance. The actual effect where three-dimensional applications are used is exactly the opposite! The smoke layering is maintained and visibility is optimised by 'pulsing' water-fog into the overhead. This has constantly been demonstrated in scientific studies, including the US Navy tests, when compared to the stream from a smooth-bore nozzle.

The flow-rate required for gas-phase cooling is dangerously low. But with a select-a-flow combination nozzle you have higher flows immediately available at the flick of a switch! Gas cooling can also be effected with high-flow automatic nozzles. You have to adjust your applications to suit the equipment and flow-rates you normally work with. This is a simple training issue.

Water-Fog tactics are optimised in non-ventilated spaces. This is not true of three-dimensional water-fog applications, which are effective in both ventilated and non-ventilated compartments.

The 'pulsing' actions at the nozzle may create dangerous water-hammer effects. The views of major fire pump manufacturers suggest that there is no danger of causing damage to fire pumps by using 'pulsing' actions at the nozzle. Since introducing these techniques in Sweden, the UK and Australia there has been no noticeable increase in pump/nozzle maintenance/repairs although there has been some problems with bursting hosereels (booster lines) when 'pulsed' at 500 psi pump pressures. This problem has now been resolved. There are engineering solutions available in terms of pressure relief valves and hydraulic retarders that can be fitted to pumps and nozzles where any concern exists.

The 'tactical solutions' and training implications associated with applying water to control environmental conditions within a fire compartment/structure go way beyond nozzle techniques. The training concepts create a greater awareness of fire growth and development; fire behaviour patterns; formations and behaviour of flammable fire gas layers; environmental and tactical risk assessment; the effects of compartmental geometry and layout; and, the tactical approach to varying situations including opening & entry procedures and the effects of tactical venting actions. This style of approach is being adopted worldwide and cites firefighter safety as the prime concern.

Firefighters in NSW Fire Brigades, Australia, demonstrating nozzle 'pulsing' techniques - To view videos and further pictures

DEFINITIONS

3D Offensive Fog Attack (Gas Cooling) - Defined as an application of water-fog discharged in short controlled bursts (pulses) where the water droplet range is critical. The objective (defensive use) is to suspend the droplets into the fire gas layers to cool, inert and dilute them, bringing them outside their immediate range of flammability in an attempt to prevent or quench subsequent ignitions. This form of application may also be used to knock-down fire-gas formations (offensive use) that are burning off inside a compartment under a ventilation controlled regime (where the amount of fire gases burning off inside the compartment is dictated by the quantity of oxygen/air entering through ventilation openings. The applications are made on a three-dimensional basis into a cubic volume of fire gases inside an enclosure (compartment or room) and the strategy is offensive - with firefighters occupying the compartment at the time of attack. This application of water-fog may be utilised both inside vented and un-vented compartments. The calculations used to quantify effect are based upon volumetric suspension (Cu. Metres etc).

Indirect (Defensive) Water-fog Attack - COMBINATION ATTACK - Defined as an application of a water-fog (or spray) where the droplet range is not so critical, the objective being to apply the water (usually from the exterior, arguably in a defensive mode) so that the droplets reach super-heated surfaces including the walls and ceiling. This creates a massive amount of hot wet steam that smothers the flames, sometimes to extinction. The calculations involved in this style of application are based upon area drenched (Sq.metres etc). Such applications are often used to great effect when backdraft conditions are prevalent.

Direct Attack - Made directly at the base of the fire-plume to reach the source of the flames, using either a smooth-bore nozzle or straight-stream or narrowed fog pattern from a combination nozzle. This attack may be either offensive or defensive, depending upon the level of fire spread involved.

ALL THREE FORMS OF FIRE ATTACK HAVE A PLACE ON THE MODERN FIREGROUND UNDER VARYING CONDITIONS

‘3D Firefighting’ – Oklahoma State University FPP/IFSTA 2005 by Paul Grimwood; Ed Hartin; John McDonough; and Shan Raffel

About the author:

Paul GRIMWOOD (Website originator in 1999) of Firetactics.com Served 26 years as a professional firefighter, mostly within the busy inner-city area of London's west-end. He has also served in the West Midlands and Merseyside Brigades as well as lengthy study detachments to the fire departments of New York City, Boston, Chicago, Los Angeles, San Francisco, Las Vegas, Phoenix, Miami, Dallas, Metro Dade Florida, Seattle, Paris, Valencia, Stockholm and Amsterdam. During the mid 1970s he served as a Long Island volunteer firefighter in New York State USA. He has four books in six languages and over 100 technical papers on firefighting strategy published.

He can be contacted at Fire4242@aol.com