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Firefighting with watermist

by Marcus
Firefighting with watermist

Tony McGuirk from Fire Bug looks at Firefighting with watermist.

“We never know the worth of water till the well is dry” is a quote by the English historian Thomas Fuller made in the 16th century. For me it symbolises a major change that is underway in terms of the way in which the more progressive fire and rescue service leaders are using our most precious commodity – water – and the reason they are being so innovative – to produce more efficient and effective fire- fighting.

The metaphoric well that is running dry represents the changing Government and public attitude to the funding of fire and rescue services whereby Chief Fire Officers are being challenged like never before to deliver safer communities within a huge cut in the funding available. Since 2010, UK Fire Chiefs have absorbed a cut of in the region of 30% cut in real budgets and this requires a very different way of doing things. This money cannot be saved by cutting general overhead and has to be met by reducing people but without reducing response times and response effectiveness.

The outcome is that I see a change in the approach of fire chiefs to the technology they invest in and the rationale behind that investment -a good example being the way in which we understand our cheapest and most effective fire fighting media – water – as well as pushing the more innovative suppliers to find ways in which water can be deployed more effectively and efficiently than ever before.

During the latter decades of the last century the fire industry created a range of additives to water which made it more effective – and more expensive and more profitable. Seduced by impressive performance data, and in a climate of a willingness to commit to this sort of technology, fire leaders invested in different water additives, such as foam, and different ways of applying the new products. The end result has been a massive industry entirely built on increasing the fire fighting capabilities of water, through expensive and often environmentally damaging additives. The majority of the fire market in one way or another is controlled by a small number of large corporations all of whom have factories manufacturing fire fighting chemicals and gases so it is therefore not in their interest to promote water!

The change I have now observed, possibly one of the very few positive outcomes of the attitude of the Government towards our fantastic fire and rescue service, has been an appetite to look again at how we use water in fire fighting – and in my view this changed attitude is a game changing one.

Water is so precious

Since the very first fire brigades were formed, the use of water as the primary fire fighting media has been at the heart of our profession. It is generally agreed that the first professional fire service was put in place in AD 6, when the Roman Emperor Augustus levied a 4% tax on the sale of slaves and used the proceeds to set up the new public fire fighting force called the Vigiles. Apparently in Roman times this was known as VAT (Vigiles Added Tax). They were divided into seven cohorts each of 70-80 men commanded by a centurion, and each cohort patrolled two of the city’s fourteen administrative regions.

Even then, water was at the heart of their fire-fighting strategy and tactics. Every cohort was equipped with a sipho or fire engine, pulled by horses and which consisted of a large double action pump that was partially submerged in a reservoir of water. The Vigiles had an expert in water, called a Siphonarius who operated the pump and an Aquarius who supervised the supply of water.

The role of water additives has also been around as long as professional fire fighting as there is evidence that the Romans used chemical fire fighting by throwing a vinegar based substance called acetum into fires. I agree with the Romans that water additives do have a role and I am not suggesting that there is no future for additives to water, but I am suggesting that we need to look again at how some Brigades are using water in a whole variety of new ways – including cold cutting and highly efficient, highly safe and highly effective fire fighting.

Firefighting with watermist

Image: Firefighting with watermist

The new technologies

Emergency services in most parts of the world continue to extinguish fires in the same way that they have done for hundreds of years using huge volumes of water. This is extremely inefficient in the majority of circumstances because huge volumes of water require large, expensive vehicles and equipment, large crews and vast amounts of water (while water remains a shortage worldwide) and the collateral water damage caused by fire fighting is no longer acceptable.

Nearly 326 million trillion gallons of water cover more than 70 per cent of the Earth, making it the most common element on the planet. Water is the only resource found naturally as a solid, liquid and gas. We drink it, swim in it, and our bodies are largely made of it, but there is still much that science doesn’t understand about water. For example, unlike almost all other compounds, which typically shrink as they get colder, water expands when it freezes – which is why ice floats on water. Yet even the reasons for this unusual fundamental property remain elusive. New water does not exist naturally; it is recycled, not created. Our water supply today is affected by our ancestors’ actions, just as our actions will affect the water of future generations, because it is all the same. There will never be more or less natural water on Earth than there is today

Understanding water is actually quite a complicated science and it is easy to therefore see why over recent years we have invested more time and energy in the science of fire behaviour, and in the development of fire engineering. Now however some of our progressive leaders are seeing that alongside a thorough understanding of fire engineering and fire behaviour, the professional fire leader of the future must also have a good understanding of water and its future role in the profession of fire fighting. In simple terms just because we have used water for a long time does not mean that we cannot look again at its role in our profession, and perhaps we are now developing the Siphonarius of the 21st century?

The thrust of this changed approach is based around using water more efficiently and extinguishing fires with water mist. Water mist is a highly scientific and specialist way of applying water vapour to extinguish fires quickly, safety and efficiently without the mess and costs of other agents. Water mist has been around for a long time however mist as a fire- fighting agent was never previously very popular due to relatively low technology giving poor fire fighting performance and the introduction of efficient water additives.

However this is now changing rapidly due to the world wanting green and cost effective product, and what could be more cost effective than water? Mist for fire fighting is a true science and involves very high levels of expertise and technology to do it properly. The changing landscape means that visionary fire leaders are looking again at how they use water, through more use of flow meters, and how they deploy water in aggressive fire attack through mist.

The new mist products are very high technology, disruptive and enable a single fire-fighter to extinguish nearly all types of fires with water safely and efficiently, thereby removing the need for expensive additives and large crews. This approach is also being accompanied with a fresh look at the role of thermal imaging and fire ventilation.

How does a great mist work?

For a fire to exist it requires oxygen, heat and fuel (known as the fire triangle). Removing any one of these aspects will extinguish or prevent the fire. Effective mist (based on droplet size) is totally unique in its fire fighting technique. It disassembles the entire fire triangle simultaneously in a way which no other agent does.

1. The droplet enters the fire flames (breaking through the convection currents as it does this) and converts to steam. This process has a huge cooling effect due to the massive surface area of mist. 1L of mist carries a surface area of 240Cubic meters. 1Litre of mist has a cooling effect of 7kg of ice.

2. While this cooling process is happening the mist is also converting to steam, and this conversion to steam uses 2257kJ of energy from the fire to convert 1Ltr of mist to steam reducing the fire’s size and aggression. This process also removes the oxygen from the fire suffocating it.

3. The actual burning fuel of any fire is a “gas like vapour” called free radicals; this gas arrives from a process called pyrolysis (the chemical process where the fuel breaks down due to heat and gives off a vapour, which ignites with the applied heat). The energy of the mist and the cooling removes this vapour effectively neutralizing the fuel and the potential for the fire to grow or spread.

Mist evolved out of water spray systems as defined by NFPA 750 (National Fire Protection Association). According to the NFPA rules water mist can be defined as any droplet size between 0.1 micron (steam from kettle) to 1000 micron (water from shower) both, which have completely different fire fighting capability. The most efficient droplet size is around 55 -75 microns with gentle kinetic energy at low/medium pressure. This has many benefits. Bigger droplets, delivered at high pressure are far too aggressive to be efficient, and they also mean that water is not then suitable for different classes of fire.

Although the NFPA spectrum for droplet size means a whole range of mists can meet the standard, the droplet size is critical to create an enlarged surface area for successful heat exchange (cooling) of the fire. New mist systems at 55 – 75 microns, delivered at low pressure means that we are able to extinguish fat/oil and fuel fires with water mist. We can also use these mists on fires with an electrical risk. The fundamental fact of importance is that we do not wet the surface as we are fighting the fire above the surface, and therefore a single attack system is now possible for the majority of fires we respond to. This is a much safer system of work for our crews

Creating small droplets below 100 micron at low pressure is very difficult, yet there are now products on evaluation that have achieved this significant breakthrough.

Some new concepts

Anyone who visited the recent Glastonbury festival, and/or the national UK extrication championships in Liverpool will have seen some of these new technologies being deployed.

Greater Manchester Fire Service (GMC) is perhaps the leading Brigade in this area and some of its new technologies were on display at these events.

Firefighting with watermist

Image: Firefighting with watermist

This picture shows their new Firebug vehicle, developed in partnership with JCB and the FireBug Group. Although the vehicle has limited water supply, the fire attack capability is comparable to a much bigger and more expensive traditional approach. The cost effective, road worthy vehicle has a highly effective mist system capable of dealing with the vast majority of fires GMS respond to. The system could easily deal with all off road fires as well as vehicle fires (including HGV size vehicles) as well as off road fires which have traditionally been time consuming and expensive to respond to (railway sidings for example).

The FireBug requires a normal licence, has excellent off road capability, and is a good example of this shift towards more efficient and effective use of the available technology. They have also created even more flexibility and capability to use the vehicle in a different community support capacity for snow clearing by having the ability to fit a snow plough and a road gritter hopper skid for the back of the vehicle. The price point for the concept is in the region of a medium family sized car and the result is a highly effective fire fighting tool which deploys the latest and most effective mist technology available, with the flexibility and reliability of brands such as JCB.

The marrying of purpose designed and market leading specialist technologies delivers a high quality product that is easy to train with and use.

Its simplicity should not undermine its capability and the tool can be used by whole time, retained and even volunteer fire-fighters alike, across urban, rural and wildland environments. – and its made in the UK!

The pictures below show another innovative tool being deployed by GMC, the backpack fire fighting low pressure mist system.

Firefighting with watermist

Firefighting with watermist

Images: Firefighting with watermist

The BacPac is a powerful, portable fire extinguishing kit, utilising cutting-edge mist technology to extinguish the full spectrum of fires. It is designed to enable rapid response to fire situations, and the system can extinguish A,B,C,D,E & F class fires, it is also safe on electrics up to 35kV. The system ensures minimal collateral damage, maximum water efficiency, is simple and safe to operate and convenient to recharge.

Staffordshire, Essex and Devon are also interested in the same technologies and other Brigades are looking at other water based technologies such as cold cutting. These concepts are good examples of how progressive leaders and Brigades are looking at how they deploy cost and operationally effective mist systems to help them respond to the many challenges of the future. I think they are to be congratulated for their courage and vision to revisit the way in which we use our most precious commodity – water – as well as the way in which we deploy into our communities to maximise the value for money of the public spend for which we are accountable.


In summary I would conclude by hoping that I have drawn some attention to the innovation that is taking place in the UK Fire and Rescue Service. The move to better understand the role of water in our profession, and a willingness to explore different tactical approaches fills me with optimism that whatever the challenges faced in the future, we still have leaders with the courage of their professional conviction to meet that future head on.

Yes, it can rain a lot in countries like the UK but we waste so much water that our rivers are now at serious risk. One third of the water we take from our natural environment is wasted – and the majority of water we currently use for fire fighting is also wasted. The mist systems now coming on the market with their incredibly small and effective droplet size mean that smaller yet equally effective response is now more possible than ever before. Understanding water is just as important as understanding fire behaviour and fire engineering, and I hope this article has helped some of that understanding.

Written by Tony McGuirk.

For more information visit www.firebuggroup.com

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