Incident Report Subject: Flame Resistant Clothing Date of Email reporting Incident: Wed 24/09/2003 13:06 Report Detail: Flame Resistant Clothing - Call for Information Note: The “flame resistance” of the clothing is provided by the flame retardant treatment of the material or its inclusion in the fibre and so such clothing is usually referred to as flame retardant clothing. A more accurate description would be “clothing of limited flame spread”. Subject: Materials used in Flame Retardant Work Wear. The choice of materials for use in the manufacture of flame retardant (FR) Work Wear falls into three general categories:
1. FR treated materials: The preferred choice of material to which an FR treatment is given is Cotton. The liquid is impregnated chemically and/or physically into the material. This causes substantial shrinkage of the material which in turn causes a diminution of its strength. 2. Inherently treated materials: These materials are synthetic materials with the FR feature included at the time of manufacture of the fibre. Flame retardancy then becomes just one of the physical characteristics of the material as is e.g. strength, abrasion resistance etc. 3. Comparison of both types of material: Lifespan of treatment: All treated materials will lose their treatment under certain conditions. The Manufacturers of the main FR treatments claim that the treatments will last for a minimum of 50 washes. "What is a wash?" Work wear gets wet not only by exposure to a cleaning, but also from e.g. perspiration of the wearer, weather conditions or firefighting water etc. and therefore in practice, these exposures must be considered as washes - or at least as a partial wash or soaking. Are these exposures included in the Manufacturer’s claims ? "At what stage does the treatment start to diminish?" Does it last for the full 50 washes; or is there a major reduction at the beginning of the wash cycle; or is it a decrease in proportion to the number of washes to which the material is subjected? This can only be established by destructively testing the clothing, so there is no knowledge of the actual level of protection available as the garment is used. On the other hand, what is inherent cannot be removed and therefore inherent flame retardancy lasts for the lifetime of the material, so with inherently FR materials, this uncertainty does not exist. b. Exposure to flame: Tests of clothing manufactured in FR treated materials on a full size body Manikin Test Rig show that at a particular temperature, the FR treatment will evaporate i.e. the treatment will remove itself when it is most needed. When the FR treatment evaporates it gives off very toxic vapours and as the treatment comprises as much as 30% of the bulk of the material, massive shrinkage of the material takes place. Comparative testing of similar clothing manufactured in inherently FR materials shows that it provides protection throughout the burning time and there is little after-burn damage. If the particular material used has even limited para-aramid content e.g. kevlar, shrinkage is at a minimum. Not all exposures of FR work wear in actual usage will be to complete engulfment in flame but knowing that this happens must be a factor in considering the safety of the product for use as Work Wear. 4. Materials that are mixtures: To provide higher levels of comfort in wear, some Manufacturers have developed mixtures of inherently FR fibres and FR treated fibres - usually a product such as a “viscose”. Viscose is a natural material with the property of "wicking" i.e. absorbing moisture and in clothing materials, this means that body perspiration is absorbed giving more comfort to the User. The principal of mixing the fibres into a material is to provide the protective features of the aramid fibre and the comfort of the natural fibre, however, in washing and in flame exposure, the treated natural fibre acts in exactly the same way as outlined above in paragraphs 3a and 3b. In recent years, the manufacturers of inherently treated materials have developed new products which combine the resistive properties of the older inherently treated materials with the comfort of the better mixtures so one of the reasons for choosing mixtures, no longer exists. 5. Conclusion: Inherently FR materials are more consistent, more reliable and therefore safer. Mixtures are better than straightforward treated materials due to the presence of a major percentage of inherently FR fibre, but because of the presence of FR treated materials, some questions of on-going efficiency remain. With current availability of comfortable inherently treated materials that come in a wide range of colours and which also contain features to protect against static electricity build up, there is only one reason to go for anything less than inherently treated materials for use in Work Wear and that reason is that FR treated products are cheaper. What price Safety ???
Caution: The comments above do not take into account any abuse of the garments due to incorrect or inappropriate use, care and maintenance of the garments. European and International Standards for Work Wear that is resistant to heat and fire:
Why are these Standards applied: Because under the Personal Protective Equipment (PPE) Directives in the European Union, it is necessary to protect Workers in PPE that is certified to comply with the Basic Safety Requirements of the Product Directive – usually achieved by compliance with European Standards. |
