Specifying products and systems for modern building projects is no easy task. Not only must a plethora of Building Regulations and standards both British and European be met, but the properties of all materials used must be fully understood.
Achieving this is no mean feat, calling upon specifiers to pick their way through a maze of information that can, at times, be both confusing and conflicting.
However, for one section of the building industry, research recently published by BEAMA helps clarify the situation when it comes to the fire performance of cable management systems.
Its Causes and Process of Fire report into PVC-U (unplasticised) cable management has highlighted what Marshall-Tufflex believes are a number of important issues surrounding the behaviour of such systems should fire break out, not least that PVC-U materials outperform many other plastic materials in this respect [fire prevention].
The report also noted that:
- PVC-U is inherently flame retardant.
- It requires an external heat source to continue combustion.
- It has a low heat of combustion and a low burning rate it therefore contributes significantly less to heat release and fire propagation than many other materials.
- In a fire situation, a low rate of smoke production is generated by PVC-U during the early stages, when personnel evacuation from an area is most likely.
- PVC-U is an effective barrier to flame spread, making a minimal contribution to fire development.
- If PVC-U is present in isolation, without other combustible materials, the high fire retardancy of the material will prevent further propagation of the fire.
Burning PVC-U chars and is self-extinguishing. It does not produce flaming droplets or burning debris, both of which are a major cause of flame spread. The presence of PVC-U therefore ensures that the ignition of adjacent products is less likely.
Charred PVC-U consists of an expanded carbonaceous structure that protects the underlying material.
Many factors should be taken into account when assessing fire risk, for example time to ignition, burning rate, heat release, smoke production and toxicity, states the BEAMA report. Escape time is a critical factor. Therefore any materials with the following characteristics maximise the chance of survival since they allow people to escape difficult to ignite, low burning rate, low heat release, low smoke production and low toxicity.
Unplasticised (rigid) PVC-U that is used in cable management systems has all these characteristics during the important early stages of a fire, the report concludes.
BEAMA goes on to discuss LSOH (low smoke, zero halogen), making the highly pertinent point that LSOH, as well as LSF (low smoke and fume) and low acid-gas does not equate with low fire hazard. In plain English, a product or system may possess these qualities but be highly flammable. Good examples, as cited by BEAMA, are petrol and TNT, both of which are halogen free.
Furthermore, the organisation tackles one of Marshall-Tufflexs pet subjects the chemical and environmental differences between PVC-U and PVC-P (PVC that has been plasticized):
PVC-U is unplasticised simply because it needs to be rigid in order to cope with the applications it is used for, for example trunking and conduit. No phthalates the chemicals which make PVC soft are used in its production.
By comparison, PVC-P is plasticized to make it flexible. Think drinks bottles, medical devices, packaging, cable insulation and sheathing etc. There have been genuine reasons for concern surrounding the use of phthalates. However, its use is now carefully monitored.
As with much of the building industry, self-regulation has driven the PVC industry in recent years. The Voluntary Commitment to the European Commission (Vinyl 2010) represents an undertaking by the European PVC industry, including Marshall-Tufflex, to push the industry towards accountable sustainability. Much work has been undertaken, not only on improving the public image of PVC-U, but also on improving its eco credentials for example by removing cadmium and lead from the manufacturing process.
The 100% recyclability of PVC-U is also often overlooked. However, because the material has such a long life span windows and doors installed 40 years ago are only just reaching the end of that cycle the feedstock for recycling is only now becoming available. And then there is the issue of collection. Local authorities, builders and demolition companies have to take extra measures to sort plastic waste from that destined for a tip or municipal incinerator. Recovinyl, an initiative of Vinyl 2010, subsidises those collecting waste and sending it to accredited recovery companies/recyclers. The UK currently has 30 Recovinyl certified recyclers, one of which Dekura processes 190 tonnes of window profile a week. Re-chip produced is then fed back into the PVC-U supply chain. Marshall-Tufflex makes use of re-chip and recycles off-cuts during the production process, recycling hundreds of tonnes of material per year.
PVC-U is an excellent building material that stands the test of time with the minimum of fuss. It is recyclable any number of times, has proven performance benefits in the event of fire and has a relatively low intrinsic oil content unmatched by polyethylene, polypropylene or polystyrene.
All in all, these benefits add up to make PVC-U an extremely beneficial and cost-effective choice, as well as an intelligent one for specifiers wishing to use an environmentally-responsible product with a long life span, low maintenance needs and documented performance and recyclability.
Marshall-Tufflex has produced a briefing document outlining the fire performance, together with EMC capabilities, time and cost savings plus environmental issues, of its various cable management systems, including Odyssey and Sterling trunking systems, SnakeWay cable support, MT32 Power Connection System and MT Supertube.
Marshall-Tufflex managing director Jim Fletcher is quoted within this document, stating: The company has been recycling PVC-U products for many years, with a well-proven performance history. It actively pursues a comprehensive programme to develop material formulations based on environmentally acceptable materials, whilst still maintaining and, where possible, improving on long-term performance.
A good example of this drive for improvement is the new MT32 Power Connection System, which not only slashes installation times for floor boxes, trunking etc, but can also offer the industry a re-usable system, negating the need to scrap wiring when a system is reconfigured.
The document also explains key terms, such as halogens and low smoke and fume (LSF), and discusses the overall benefits of PVC and PVC-U: PVC is one of the most successful modern synthetic materials. It makes excellent use of scarce resources, is long-lasting and safe in production, use and disposal. The effect of PVC on health and the environment, from manufacture to disposal, has been more thoroughly researched than almost any other synthetic material.
To see the full BEAMA report go to www.beamainstallation.org.uk
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