West Midlands Fire Academy is leading in the study of the effects of wind-driven fires. Ann-Marie Knegt visited the facility and donned fire kit to experience the behaviour of compartment fires.

At West Midlands Fire Service Academy (Birmingham, UK), Carl Batchelor, Dave Payton, Mark Russon and Jim Grove all work as lead instructors on breathing apparatus, fire behaviour and positive pressure ventilation. This particular unit within the training academy has done a lot of research, testing and development on high-rise fires and especially on wind-driven fires.

The West Midlands Fire Service covers an area that includes the second most populous city in the UK, Birmingham, and which encompasses a large number of built-up areas with a diverse range of building types.

Dave Payton kicked off the conversation by explaining that West Midlands Fire Service utilises offensive interior firefighting tactics following their introduction by the Swedish Fire Service around 12-14 years ago. Since that time the fire behaviour team has been constantly testing and reviewing its offensive interior strategies with the help of tactical ventilation and thermal imaging technology, and has even introduced new equipment in the UK designed especially for the response to high-rise fires.

Floor Below Nozzle

Dave Payton explained that some of the team members visited a conference organised by the FDNY (Fire Department New York) where they witnessed a presentation from Battalion Chief George Healy, who revealed the results of tests the FDNY had carried out on fighting wind-driven fires on Governors Island. During these tests the FDNY utilised an extended branch pipe with a 60 degree bend, called the Floor Below Nozzle.

The fire behaviour team was both intrigued by this method and impressed by the success that the FDNY had experienced with the nozzle, so the team went to see if they could acquire one from the US. As this wasn’t possible they requested the specifications from the FDNY and commissioned UK-based Delta Fire to create a Floor Below Nozzle. The new device was recently launched at the Emergency Services Show in Birmingham, and Payton explained how it works. ‘The branch pipe is three metres long with a bend in the middle. It has a 22ml smoothbore nozzle at the end. The device is connected to the normal riser stream, fitted in high-rise buildings, but positioned on the floor below the affected compartment. It works by delivering a large volume of water into the compartment of origin. It is delivered in a straight stream and the water hits the ceiling of the affected compartment radiating the water in large quantities within the compartment. The effectiveness of this solution lies in the volume of water. We tried it with smaller sprays and water mist, but when you consider the effect of the wind this had very little effect.’

By deploying the Floor Below Nozzle the temperature in the corridor adjacent to the fire compartment can drop from 500-600oC to around 150oC in as little as 17 seconds.

Whilst not a fully scientific test, it is clear that the branch has a dramatic affect on the fire, and that its effect in high-rise firefighting should not be underestimated.

The branch has several advantages, for instance a firefighting team that has been caught on the fire floor with injured crews or residents now has the opportunity to retreat. Emergency teams can enter the fire floor and help evacuate injured crews and residents.

Jim Grove added that this also provides the responding team the breathing space to attack the fire. ‘As long as the wind is blowing and there is fuel in the fire compartment, the fire team will struggle to approach it, especially when faced with such extreme temperatures, making a direct fire attack almost impossible.’

The Floor Below Nozzle enables the team on the floor below to attack the fire from the outside. When the temperature has come down sufficiently for safe approach the branch is then turned off. The team on the fire floor can then strategically suppress and extinguish the fire in the compartment.

Another aspect that has been extensively researched by the fire behaviour team is ventilation during high-rise fires, as its correct application can help firefighters immensely during a response.

It is widely accepted that many ageing high-rise buildings do not comply with modern safety standards. ‘In many cases fire protection measures have been compromised due to varying factors such as poor contractor work when installing new cable systems, fire doors that have been vandalised, and other reasons,' said Jim Grove.

Dave Payton added that another problematic factor that causes many issues is modern-day fire loading. ‘The fuel loading package in today’s dwellings is completely different from what was in there 20 years ago. When thinking about the furniture present within compartments, much of it will have a high-glue content, or contains plastics, and then you have DVDs etc. Basically, the volume of hydrocarbons and chemicals is much larger than ever before. So even though we tend to get fewer fires, they have the potential to be faster in growth and further on the development scale than 10 years ago – and also more dramatic.’

Carl Batchelor highlighted this with the example of a burning piece of furniture made of solid wood – the type that used to be manufactured 30 years ago. ‘The energy required to burn a solid piece of timber is huge, whereas compressed and glued furniture will start decomposing at a much lower temperature, producing a lot more combustion gases. This obviously affects firefighters, because the energy that is being released in modern day fires is huge, maybe three to four times more than even 10 years ago.’

Applying the correct ventilation is paramount to both fire suppression and firefighter safety, so the WMFS Academy developed a PPV instructor’s course, to meet the needs of this critical training. The team conducted research into fire gas flow paths while also analysing European and American ventilation techniques. ‘The optimal ventilation strategy should lie somewhere in the middle of both ways of working. For years we didn’t ventilate at all here in Europe because we thought everything would blow up. In the US they thought the opposite. Slowly but surely we are all coming to the same point,’ said Dave Payton.

All members of the team emphasised that ventilation strategy cannot be viewed as a finite science, because too many factors are at play during an incident. The decision on how, if, or when to ventilate depends on factors such as fuel loading, water flows and pressure, fire flow paths, and weather.