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Fire protection solutions for important business areas

The consequential costs of an operational interruption after a fire are often graver for an industrial company than the actual damage to buildings and assets.

In the protection of essential machinery and equipment, the faultless interaction of fire detection and targeted extinguishing is a central aspect. As a replacement for halon extinguishing systems, new solutions adapted to industrial applications and using chemical extinguishing agents, natural extinguishing gases and water fine spray systems are offered on the market today.

It is undisputed today that fire protection measures can often prevent or at least limit damage to people, buildings and the environment. Yet in spite of legal regulations and advanced fire protection technology, a study conducted by the German Association of Property Insurance Carriers (VdS) shows that two out of three manufacturers are unable to recover from a fire that results in an interruption of production and vanish from the market within only a few years. This results not so much due to direct damage to buildings and equipment, which are usually covered by insurance, but first and foremost from the uninsurable consequential costs of business interruptions (inability to produce, absence from the market, loss of customers etc).

Protecting technology

Driven by the breathtaking spread of information technology and computer-controlled equipment, by electronic data processing and e-commerce, today's enterprises are highly networked and their processes are interdependent. An interruption in the flow of data or loss of data can immobilise entire production units and severely disrupt business operations. This is why it is important to have a protection concept that both individually reflects the customer's risks and requirements while offering the appropriate, effective, integratable solutions.

A smooth interaction between fire detection and targeted extinguishing is a key aspect in protecting high-value assets and important operating facilities.

A failure analysis conducted by the VdS localises most system failures at the interface where the fire detection system electronically activates the mechanical extinguishing system. Especially in safeguarding against business interruptions, the time that elapses between detection of the fire and activation of the extinguishing system is considered to be the critical factor in containing a developing fire. Consequently, it is vital that the extinguishing system be matched to the fire detection system, and that the correct detection system, in turn, reflect the existing risk situation and protection objectives. This necessitates a detection system that is not based merely upon standard applications but can also be programmed for special needs and supplemented with a wide range of extinguishing functions. A prerequisite for this is the greatest possible level of detection reliability in order to be able to identify the fire risk early on and avoid false alarms and/or unnecessary extinguishing. Unnecessary activation of the extinguishing system can have far-reaching consequences, as in many countries it is necessary to shut down operations until the extinguishing system is operational again.

Fire extinguishers

There is no universal extinguishing agent for all types of fires. As a result of its potential for damaging the ozone layer, the extinguishing gas halon, which had long been considered to be an outstanding extinguishing agent, can no longer be employed. Siemens Building Technologies offers a variety of solutions that can be flexibly matched to the application and/or local needs in question. These include a chemical extinguishing agent, natural extinguishing gases and a newly developed water fine spray system.

The new extinguishing agent Novec 1230 is the first chemical alternative to Halon, that does not have a damaging effect on the ozone layer (Ozone Depletion Potential value = 0, Global Warming Potential value = 1) and is not affected by the emission limitations according to the Kyoto Protocol. The extinguishing agent is stored in liquid form, thus requiring little storage room. In case of activation, Novec is transported to the extinguishing nozzles with nitrogen as propellant; it then evaporates in the room, generating an extinguishing effect similar to that of Halon.

Gas as extinguishers

So-called inert gases can be used in many extinguishing systems today. Inert gases are extracted from the natural environment and employed in concentrated form for extinguishing purposes, without posing any hazard to people or the environment. Siemens Building Technologies uses inert gases in unmixed form, ie pure nitrogen (N₂), pure argon (Ar) or pure carbon dioxide (CO₂), depending upon the application in question. Their advantages over the expensive premixed gases that are in such widespread use today consist of their demonstrably better extinguishing effect (CEA research project), as well as the ability to replenish them quickly, cost-effectively and locally. Nitrogen and argon are not hazardous to people, while the employment of carbon dioxide always necessitates protective measures for the population of the facility, as it poses the risk of suffocation.

Both inert and chemical extinguishing gases provide their extinguishing effect by displacing oxygen, making them ideally suited for enclosed major operational facilities (data centres, telecommunication systems, switching substations) or rooms containing high-value assets (fur storage warehouses, archives).

Water options

Specially adaptable water mist systems produce good extinguishing results. This technology is predominantly employed to protect specific objects (energy generating systems, engines, pumping stations) as well as for room protection or even in tunnels. Depending upon the application in question, the volume of water and/or droplet size is optimised in such a manner as to act directly on the source of the fire and quickly produce a strong cooling effect. Optimum droplet size is crucial: if they are too small, the combustion gases prevent them from reaching the fire; if they are too large, the great difference in temperature splits them apart when they come into contact with the flames. In both cases, they are insufficient as a cooling medium in the core zone.

This extinguishing technology is also suitable for liquid fires (gasoline, diesel fuel), which quickly develop a high level of combustion energy and therefore have to be quickly contained. In addition to their extinguishing effect at the direct source of the fire, the water droplets also cool the hot surface, thus preventing flashback to the combustible vapours of the liquid. Depending upon the application in question, the mist can be additionally enriched with nitrogen to enable the system to also operate at normal room temperature and/or be employed in combating smouldering or incipient fires. This is an advantage over conventional water mist systems that operate by displacing oxygen with steam and require a stable vaporisation temperature of 80°C as well as enclosures around the object to be protected.

A modified water mist spray system is employed in tunnels, because - in contrast to object protection - tunnels involve different protection objectives. Since it would be virtually impossible to extinguish a vehicle fire in a tunnel with water, it is therefore necessary to directly cool the location of the fire and prevent the fire from spreading to other vehicles. To do this, multiple tunnel sectors, preferably 30 metres in length, are flooded with water spray; here, too, the water droplets have to be sized correspondingly larger, depending upon the requirements in question.

Safety, reliability and long-term utilisation necessitate careful planning and coordination between purchaser, planning engineer, authorities and system vendor. In addition to the individual system costs, it is also necessary to take into consideration installation, interfaces, maintenance and services. Because the right combination of measures and smooth interplay between them make fire protection both reliable and efficient.

Replacement of halon

Halon was a good extinguishing agent that produced a strong extinguishing effect, was not hazardous to people and could be stored in small quantities. As a result of these properties, halon was used without hesitation for a wide range of extinguishing applications during the 1960s and 1970s. With the Montreal decision, in 1987 the major industrialised countries agreed to phase out the production and employment of halon as a result of its ozone damage potential (ODP). In the countries of the European Union, halon extinguishing systems had to be dismantled or replaced by the end of 2003.

It is not easy to convert a halon-operated extinguishing system to an alternative extinguishing agent, because the available extinguishing gases produce different extinguishing effects and require more space. Moreover, halon has to be properly disposed of. Many enterprises have evolved over the course of recent years, and there have been corresponding changes in asset values, technical equipment, risks and protection objectives. At the same time, there have been improvements to both the available offerings and system technology in technical fire protection, which means that suitable and capable alternatives to existing Halon extinguishing systems exist today.

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