Firefighting technology, tactics and crocodile traps
FIRE Correspondent Tony Prosser reports on the evolution of firefighting technology that has saved lives and, on occasion, proved a false dawn
On Remembrance Sunday, the head of the British army, General Sir Nick Carter told Sky News that it could be possible that in the 2030s, the British Army could include around 30,000 “robot soldiers” forming 25 per cent of its establishment. But before everyone starts having nightmares about thousands of “terminators” running wild across the planet, they should be reassured that the Ministry of Defence (MOD) policy is that “only humans will be able to fire weapons”. Phew!
While it may not be policy, the piece also has details of technology being developed which can fire weapons and includes a drone with six rotors and armed with two shotguns intended to be used in the built environment to storm captured buildings, while other robots which can either be used autonomously or through remote control.
Firefighting robots have been used for nearly 40 years in one shape or another and have been developed for specialist applications such as firefighting in particularly challenging environments such as ships, oil refineries and more recently, wildfires, in situations where the risk to firefighters is excessive. While an autonomous “robofirefighter” may be some decades away, other technological advances in the last 30 or so years have helped change the way firefighters tackle fires and other incidents, sometimes successfully, sometimes not. And the application of new technology has led to the need for different tactics and techniques to be developed to make sure that the use of technology delivers the best bang for what is often a very big buck.
Although fires are extinguished by removing heat, oxygen or fuel, the way it has been achieved has evolved over centuries and will undoubtedly continue to do so. Inevitably with the introduction of technology, firefighting tactics also needed to evolve. The extinction of oil and fuel fires using foam was once an innovation which led to a whole branch of fire science. Initially made from the blood of animals, foam has now evolved through synthetic, efficient but less friendly to the environment to newer generations which are biodegradable and less damaging to the biosphere to the same extent.
As technology, both in theory and in practice, gets more sophisticated, it makes firefighting more efficient and, at least in theory, safer for firefighters and better for society and victims of fire. But technological advance is not necessarily pain free, particularly when the innovation is seen as a panacea for all ills to the exclusion of other “tools” in the box.
Technological ‘Game Changers’
High end technological advances, when introduced steal much of the limelight but are now so ubiquitous it is easy to forget that a decade ago, they were game changing. Telemetric BA sets are a case in point. The ability to monitor the precise contents of a BA cylinder, calculate time of whistle and “due out” times, automatically alert the entry control officer in the event of a loss of mobility or entrapment, act as a facility for warning wearers of the need to evacuate, have greatly enhanced the safety of firefighters in the most hazardous working environments.
These changes have not all occurred at once but have been a step-by-step incremental process over several decades. Remote monitoring of BA wearer’s body temperature, heart and breathing rates as well as the external monitoring of environmental conditions is also possible but again with a price tag.
The increase in the perception of safety can have negative effects, of course, in that firefighters may be allowed to fall into the trap of having a false sense of security because of the features in the BA set and take even greater risks as a result of the technological comfort blanket. A similar argument was made when traditional firefighting personal protective equipment (PPE) – essentially the same gear used by “Blitz” firefighters in the 1940s – was replaced by more sophisticated, better designed and manufactured tunics, leggings and helmets towards the end of the 1980s. Thermally resistant and ergonomic tunics and leggings, helmets and, particularly, the introduction of flash hoods, led to a widespread concern that firefighters were insulated from the physical environment. This, it was believed, would prevent them sensing critical changing conditions sufficiently quickly enough to enable them to evacuate a dangerous structural fire, for example, as they would not recognise rapid increase in temperature which could lead to a flashover or overestimate their physiological state. Indeed, at the time the concerns about environmental insulation and the risk of overheating meant the advantages and additional protection given to the firefighters was sometimes forgotten. Nevertheless, despite the concerns, burns to firefighters have reduced in number and severity and the latest designs of PPE have recognised the risk of physiological exhaustion and attempted to reduce the thermal load added to the body mass.
It is hard to believe but thermal imagery is now over 100 years old having been invented by the Hungarian Kálmán Tihanyi in the early 20th century for the British government seeking to produce effective anti-aircraft defences. Thermal imaging cameras (TICs) for the FRS were first introduced in the 1980s as a specialist piece of equipment carried on a few appliances due principally to the cost. The first recorded civilian rescued using the TIC was on January 10, 1985 at the Putney gas explosion in London, although it had been first used at the Brighton Grand Hotel explosion on October 12 the previous year.
This revolutionary piece of “kit” would eventually go on to radically change the way search and rescue and firefighting operations are conducted across the world but even in the UK its adoption has been delayed by sequential financial crises and fiscal belt tightening policies. Helmet mounted cameras, the ultimate evolution, have been available for nearly two decades but uptake is again limited due to costs despite the obvious advantages of being able to “see through smoke” and extinguish fires and rescue casualties more rapidly.
A similarly long gestation period has followed the introduction of positive pressure ventilation (PPV) to the UK, first identified as having potential for use in the UK by Home Office Fire Research and Development Group (FRDG) in 1994 as part of the Large Fire Project (FRDG Report 6/1994). The subsequent report, No 81/2000, set out what has become the three phase approach to tactical ventilation using PPV: a ‘use of PPV continuum’: (a) the use of PPV for post-fire smoke clearance and damping down; (b) smoke clearance as part of firefighting; and, (c) the use of PPV for offensive ventilation in domestic and other premises. Unlike the use of thermal imagery in firefighting, PPV has not been used to its full potential in the UK. Unlike the USA, where many domestic buildings are constructed of predominately timber frame and cladding, British (and most Western European) homes are brick and concrete which means that extinction using PPV can be more technically challenging. While some FRSs have embraced PPV fully, the level to which techniques (a to c) are used remains a patchwork and reflective of the level of skill, and, consequently, the number of hours required to develop and maintain competence can be significant.
There remains the dichotomy of placing PPV units on every station and devoting much time to training but having an immediate availability or to restrict deployment to a few stations (with an intensified training regime) and risk a delayed ventilation intervention. For this reason, some services only use PPV for post-fire smoke clearance while others use PPV for offensive firefighting, and many services have moved up and down the “use continuum” over the decades.
At a less sophisticated level, water is still the main method by which fires are extinguished but the methods of delivery have become more efficient with technological advances. High pressure hose reel jets were introduced in the 1960s and revolutionised firefighting by delivering relatively high volumes of water (150 litres per minute (lpm)) at 30 plus Bars pressure, allowing a spray with small droplets to absorb greater quantities of heat, thus cooling and extinguishing fires quickly. It also reduced the collateral damage caused by excess water when main jets (up to 500 lpm) were used. The fire in Zephaniah Way, Blaina in 1996, which killed two firefighters, caught in a high-speed deflagration, led to fundamental changes in the way compartment fires were fought. Pre-entry cooling of fire gases became essential training to all firefighters in the UK anxious to avoid a repeat of the tragedy and became indoctrinated across the UKFRS.
While firefighting techniques involving gas cooling have reduced the risk of firefighters becoming caught in a flashover, deflagration or backdraught, the adoption of gas cooling as “the way” all property fires should be approached has become something of a potential “crocodile trap” funnelling firefighters and incident commanders into adopting inappropriate techniques in some circumstances. The use of gas cooling in already ventilated compartments is likely to be redundant and ineffective as is its use in large open, compartmented spaces including warehouses and factories. The use of gas cooling and hose reels at some fires in these circumstances have led to firefighters getting into difficulties and being injured.
As knowledge of fire dynamics has increased, equipment has itself become more precise in its application with ultra-high pressure (UHP) equipment delivering up to 80lpm at pressures of over 70 Bars, with some systems operating at 300 Bars and having the ability to cut through walls (“cold cut” using metal or other abrasive filings injected into the pressurised water stream) to extinguish or suppress fires prior to firefighter entry into compartments.
The use of high and ultra-high pressures in water extinguishing systems have been successfully used in response to improved understanding of fires. In an attempt to reduce the potential for a backdraught (and also to provide a means of attacking a fire where entry through doors and windows is difficult due to reinforced security systems, etc) UHP systems can use “cold cutting” techniques to “punch” a hole through walls enabling a fine spray of atomised water to suppress the fire. Like “gas cooling”, the optimal technique for use of UPH jets involves an integrated approach using thermal imagery, UPH systems and ventilation. An example of the new tactical processes for use (developed by Cobra, a leading manufacturer) uses a number of stages. The outside of the structure, building or room is scanned using a TIC to gather critical heat signature and thermal streaming information. Information on colour, pressure and flow of fire gases is also captured. This allows the identification of most advantageous points to begin a fire attack. The jet from the “lance” pierces the wall, door or window to create an initial hole in the structure envelope and injects the high-pressure water mist into the compartment to cool fire gases and suppresses or reduces the fire. Once the fire has been suppressed, PPV fans can be deployed to remove fire gases, products of combustion and steam, and replace these with a flow of fresh air.
This optimised approach to fire suppression illustrates the dilemma fundamental to the provision of a response to a fire particularly where a rapid attack is needed to facilitate a speedy entry for rescue or prevention of rapid escalation. Does an incident commander delay intervention until the full level of resources – TIC, UHP and PPV (not always available on all appliances) – are in attendance or use a sub-optimal solution to achieve a successful outcome but with increased risk to firefighters? A difficult judgement call between “doing things right” and “doing the right thing”.
The obvious solution would be to provide all the required equipment on a vehicle with sufficient crew levels to enable immediate deployment and fire attack: a solution that appears to be pure fantasy in the current economic climate and may not be achievable with a standard attendance of eight firefighters (eight is the new nine or ten) at a house fire? The incorporation of UHP hose reels and a small water supply has been shown to be successful at small fires and in wildfires using the high latent cooling capacity to knock down flames. There have, however, been some issues with UHP HR having insufficient cooling capacity to completely extinguish a car fire without the “big water” back-up held on a major pumping appliance.
Some innovation has had unexpected benefits. Compressed air foams systems (CAFS) have enabled a high-volume foam capability to be built into most frontline appliances, enhancing fire suppression for a wider range of fires and very rapidly deployed. Apart from the obvious foam properties, the use of “sticky foam” produced by using less water in the mix has been shown to provide a barrier to fire spread to adjacent buildings by providing a thermal insulating layer on walls, roofs (particularly thatched) and sometimes on grass and heather to restrict spread at wildfires.
Less successful has been the attempt to use CAFS-based foam systems for an interior attack on a domestic fire. In concept this could be achieved but the reality is that an interior foam attack is too difficult to achieve because relative large size of foam water mix droplets do not absorb heat to the same degree as fine water mists and so cooling of the gasses is limited. But then again, very few extinguishing media are universal in their application. What innovation should provide (and these relatively new techniques do) is an additional tool in the box which firefighters and commanders can use selectively to gain an optimised intervention for a particular situation.
‘Bots and Drones
With regard to the use of robotics, there are many potential uses for self-driving vehicles including fire appliances and other vehicles. Tried and tested uses include specialist equipment to carry out reconnaissance and fire attacks remotely in high risk environments such as nuclear installations (now on the rise in the UK again) oil refineries and with the potential risks associated with biohazards and chemicals. Again, cost will be the deciding factor in whether the FRS can afford such expense.
While drones are now becoming commonplace and relatively cheap, their use should no longer be confined to command units or specialist support. The ability for an incident commander on the first attendance to see a 360° image of the incident ground and possibly close ups of critical areas will enhance the command and control (and safety) at that incident. The loss of such a device is no longer critical if the cost is only a couple of hundred pounds, compared with the £20,000 plus cost to early adopters of drones. The new generation of firefighters, the “digital natives”, will have no problem in the operation of such devices and there may be a time when operation of drones or other robotic devices can be carried out from inside a warehouse in Stevenage and imagery sent directly to command units, command points or even directly to sector commanders at incidents. As with most things, technology follows the money and at the moment the military are setting the pace.
Hopefully, the emergency services will be similarly endowed with the resources to use “steel not flesh” to fight the challenging fires of the future and increase the safety of firefighters on the ground.
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