11 Jul Limiting the consequences of fire
Tayfun Eren, Product Manager for the Prysmian Group examines the EU standard 50575 of the Construction Products Regulation (CPR): More safety in buildings.
People spend 90 percent of their time in buildings where around 90 percent of all fires occur. The leading cause of death in building fires is exposure to toxic gases or smoke with more than 91 percent of all victims dying as a result. What is disastrous is that the evacuation time from a fire has become significantly shorter in recent decades. While in 1950 there was about 15 minutes to escape, nowadays it is only about three minutes to evacuate. In addition, smoke produced during fire reduces visibility that people are not able to see escape routes and they are exposed to a dense, obstructive cloud of toxic combustion gases.
This development is primarily caused due to the increased use of plastics in buildings with increasing installation density. This shortens the time from ignition to dangerous flashover enormously. Flashover refers to the abrupt transition from an incipient fire to a fully developed fire. This is the moment when air entering the room causes the pyrolysis gases to burn under the ceiling. The resulting high temperatures cause all inflammable objects in the room to catch fire within a short time, even without contact with a pilot flame.
Greater safety through prevention
Preventive, passive fire protection measures are effective and increase the protection of life and limb in the event of fires in buildings and structures. Fire protection measures are taken in advance to counteract the emergence and spread of fires and to limit the consequences of fires as far as possible. This includes technical, organisational and constructional measures. The structural measures are very versatile and take into account primarily the aspects of fire behaviour and fire resistance of building materials, division of the buildings into fire compartments and escape route planning.
With the Construction Products Regulation (CPR), which has been binding for all EU member states since July 2013, the EU has standardised the various national regulations regarding the fire properties of construction products. The CPR regulations are accompanied by an extensive certification system which ensures that only approved products are used in construction.
The CPR applies to all products or kits that are permanently installed in structures or parts of them. Since 1 July 2017, the CPR respective the newly introduced EU Standard 50575 includes permanently installed cables and wires.
The CPR regulations define fire classification and test methods. It replaces the previous fire classes with seven new classes: Aca, B1ca, B2ca, Cca, Dca, Eca and Fca. Some European regulators and associations have defined the new high fire classes of Cca and B2ca as minimum requirements for numerous constructions and buildings, where safety of people are concerned, such as schools, hospitals, high-rise buildings and buildings with a high number of people. According to standard 50575, permanently installed cables and wires must be tested and classified for energy content, flame propagation, smoke generation, acidity, heat release and fire droplets.
CE marking and DoP
Cable manufacturers may only sell products that have a CE marking and Declaration of Performance (DoP). The CE marking must be affixed visibly, legibly and indelibly to the product labels and to rings, coils or cable reels. Other necessary markings on the cable, packaging, label or accompanying documents are origin, description and reaction to fire class.
Manufacturers are also obliged to draw up a declaration of performance covering the performances of the main product characteristics. Throughout Europe, the evaluation and description of these properties are carried out on a uniform basis. This makes it possible to compare products independently of the production location. The declaration of performance shall also include information on the use of the product, the manufacturer and whether an external body has been involved in the production control. A product receives CE marking only after successful testing and issue of a declaration of performance.
Fireproof cables on the market
In order to comply with the demanding fire classes and keep smoke and toxic gases to a minimum level in the event of a fire, BU Multimedia Solutions of the Prysmian Group offers a complete range of high fire safety Cca and B2ca certified fibre optic cables with up to 288 fibres. They are waterproof, protect against bending/ physical effects and are suitable for indoor and outdoor use.
Conclusion
Compulsory compliance with EU Standard 50575 of the CPR was an important step towards greater fire safety for people, animals and goods. The increase in installation density in modern buildings and structures required that cables and wires become the focus of preventive structural fire protection measures. Cables can cause fires as well as transferring them from one room to another. Hence, cables must be designed to limit and inhibit the spread of fire, for example by reducing flame propagation, heat release, fire droplets or smoke and gas emission. Finally, the flame retardance of cables is an important requirement in order to reliably detect and extinguish sources of fire via fire alarm systems or sprinklers.