Modern Building Services

FEATURE INSTALLER VIEW MODERN BUILDING SERVICES FEBRUARY 2021 17 More information can be found at www.flexicon.uk.com To assess how flame retardant a material is, the normal test method is to measure the Limiting Oxygen Index (LOI) according to BS EN ISO 4589-2. This determines the percentage of oxygen that needs to be present to support combustion. The higher the LOI percentage, the greater the flame retardancy of the material. Another method is to use a glow wire test, BS EN IEC 60695-2, which applies a glow wire to a plaque of material at 7500C, 8500C or 9600C. Low smoke emission If the conduit is involved in a fire, the smoke generated may obscure the vision of people trying to escape, or the firefighters trying to extinguish the flames. It is important that the flexible conduit specified provides superior protection if this scenario occurs, to ensure staff are afforded sufficient time to exit the building safely. There are a number of fire tests, where a specified sample of material is burnt under controlled conditions in a given size smoke chamber and the smoke obscuration of a defined beam of light is measured. Low toxicity The generation of toxic gases may incapacitate people trying to escape from the fire, so appropriate protection must be provided at all times. To test for toxicity, a specified sample of material is burnt under controlled conditions in a given size smoke chamber and the fumes are analysed for various gases. The concentration of each gas is then multiplied by its toxic potency to give a toxicity index. If halogens, sulphur or phosphorus are present in a material, it is unlikely to pass the low toxicity tests. Halogen free One of the main misconceptions is that a halogen-free material is automatically a low fire hazard product. A material cannot be considered as low fire hazard if it contains halogen, but as we have learnt, without the accompanying low toxicity, low smoke and flame- retardant properties, it will not meet the full criteria. Typical halogens are fluorine, chlorine, bromine and iodine. Chlorine is the most common in PVC, fluorine is present in fluoro-polymers and bromine appears in flame retardants. All of them produce highly toxic fumes and thick smoke if exposed to a naked flame; another reason why operators may have tended to rate this area of performance above other fire hazard properties. Specification first It is also worth remembering that specifying cable protection based on one property alone can be a costly mistake and the full range of environmental factors should be considered. These can include exposure to extremes of temperature, UV radiation, harsh chemicals, compression strength, abrasion resistance and the likelihood of water or dust ingress. While many products may look the same, performance properties can vary greatly so customers should always check suitability and compatibility for their application and consider the installation as a complete end-to-end system. Reputable conduit suppliers will provide product and material fire test reports to support their fire performance claims. These test reports should come from accredited fire test laboratories and should be less than five years old. In conclusion According to the Uptime Institute, many operators admit that most downtime incidents could be avoided if they were to invest more in the resiliency of their facilities, making it vital to put robust measures in place to mitigate against the risk of fire. This should not only include the physical hardware and infrastructure, but extend to all aspects of an installation, particularly the performance of essential data cabling. By considering all aspects of fire performance, operators can ensure the ongoing security and longevity of the installation.