Thumbs up for water mist

Thumbs up for water mist

The big cities of this world boast stunning skylines. They are like fingerprints. The problem is that the average fire ladder extends to 30 metres only while a high-rise building is – by definition – 45 metres or higher writes Bettina McDowell, Secretary General of the International Water Mist Association (IWMA).

As Gary Howe, Senior Fire Protection Engineer with Zurich Risk Engineering, points out: “More and more  high-rise buildings are being erected every day in cities around the world.” So, there are many people at potential risk worldwide: people working on upper floors, living in blocks of flats with not enough (protected) escape routes. And Gary adds: “Fire risks may be increasing with the use of combustible modern construction material and methods”.

Ryan Conaghan, Sales Director for Marioff UK, says” A high-rise building is typically a multi-purpose building with several hazard categories.” But there are also straight forward office blocks and blocks of public housing flats, like the Grenfell Tower in London.

There are already a number of high-rises in the UK and around the globe fitted comprehensively with water mist systems. Two projects by Marioff in London: Vantage Point in London is a 1960s office to residential retrofit with apartments, plant rooms, generator set and communal areas protected whilst  Creekside Wharf,  a 70 metre high new build, of modular construction, is similarly protected plus the car park and bin store. Sounds very much like complete building protection.

Plumis offer a different concept: partial protection. Automist is a low pressure mid-wall mounted stand-alone system which prevents the fire from spreading from the room of origin where sparks from a faulty electrical appliance may cause a catastrophe. Surrey Towers has been retrofitted with the system because it is easier to retrofit than other active fire suppression systems.

Dean Reeve, UK and Ireland Agent for VID Fire-Kill, stresses: “Yes, water mist is acceptable for high-rise buildings.” He adds: “There are published British Standards and the scope of these standards gives guidance and recommendation on the design, installation, water supplies, commissioning and maintenance of water mist standards.”

The insurance industry will always ask “is it installed as designed? Is it installed correctly? And: will it work?” But as Dean Reeve puts it: “If a project is going to use any suppression technology, it is not acceptable for it to be designed and installed by a company that does not have the proven training and skills in that exact technology.” Indeed Gary Howe admits that if he finds fault, all kinds of fire protection systems (gas, foam, conventional sprinkler systems) are affected. The discussion should therefore remain within the framework of advantages versus disadvantages and challenges versus solutions.

One chief advantage is the amount of water needed to be stored and pumped up. David Sherrington of Ultra Fog focusses on the design and  development of systems for residential, commercial, and industrial applications within the UK.  He emphasises the reduced demands on water supply, smaller diameter pipework and reduced water damage due to a consumption of 80 to 90 per cent less water than conventional sprinkler systems.

The smaller droplets have a larger overall surface which means: rapid cooling, reduced transmission of radiant heat and greater interaction with smoke particles. In relation to existing high-rise buildings, he says: “Successive building works, interior refits and modernisation can result in the undermining of compartmentation and  the building’s fire-stopping may not be fully re-instated during completion of the works.  When fire-stopping materials are insufficient or incomplete, fires in existing buildings can spread rapidly and unpredictably.  According to the inquest, this is what happened in the fatal Lakanal House fire in 2009. The “stay put” policy which was in place was reliant upon compartmentation, which was compromised even before the fire started.” This fire spread rapidly – both vertically and horizontally – and left six people dead.

David Sherrington explains: “Extensive smoke logging of the communal areas prevented the rescue.” He is convinced of the unique opportunity for water mist to play an important role as a means of escape and says: “When installation of sprinklers within individual flats of a high-rise block is not practicable, the use of water mist within the building’s escape routes should be considered.” His proposes water mist nozzles immediately outside the entrance of every flat, water mist dry risers within the communal stairwells and corridors with a water mist pump unit at ground level – accessible only to the fire brigade, and activated only in the event of failure of compartmentation. The key advantages he sees would be the costs to install water mist only within the escape routes would be considerably lower than to go into each individual flat. Installation within the public areas would not affect the private flats. He stresses that this approach would only cause minimal changes to the fabric of the building.

In 1874, Henry S. Parmalee created the first automatic fire sprinkler. Frederick Grinnell manufactured this sprinkler and in 1882 designed the more effective Grinnell sprinkler. Since then, this technology has basically remained unchanged.

In 1885, Carl Benz, developed an automobile powered by a single cylinder four-stroke engine. Nowadays, nobody drives this kind of car anymore.

However, not enough people seem to appreciate the further development of water-based fire protection systems and spot the limits of conventional sprinkler systems. Water mist systems are advanced sprinkler systems which supersedes the discussion about equivalency – a discussion which in fact often lists the shortcomings of sprinkler systems. Magnus Arvidson (RISE) concludes – in a report summarising a research project comparing both systems – that low pressure water mist (which is obviously closer to a traditional sprinkler system and shares the same base pressure class for components, from the pumps, and tanks, through the pipe system, strainers and valving, to the detection and delivery devices) protected better than traditional sprinkler systems or equal.

The 18th International Water Mist Conference takes place in London, UK, on 19th and 20th September 2018. Visit iwma.org. for further information.