This feature is just as critical as protecting and PROPERLY washing your FR clothing because if you didn’t the FR level is wasted and lost and you are now a human candle! So you work on site and your SUPERVISORS told you about this topic and why it is so important!
Flash fires and explosions are common hazards at a variety of workplaces. These hazards are present in work areas where flammable materials are handled, processed, stored, or in any way present. In the petrochemical industry for example, flash fire can occur at well head sites, collection points, compressor stations, refineries, and petrochemical and plastic plants. In such areas, the potential exists for developing an explosive atmosphere capable of injuring or killing workers and causing extensive property damage. Industrial flash fires and explosions result from the accidental release and ignition of flammable fuels. The words “Inherent” and “Treated” are commonly used when referring to flame resistant (FR) fabrics, but very few people understand the relevance of the terms.
In addition, ensure that you select garments based on the following: − thermal protective characteristics of the fabric − physical characteristics of the fabric − garment construction and components − avoidance of static charge build-up − design of garment – requirements for labels, logos and high visibility striping − conditions under which workwear will be worn − comfort of fabric and garment − cleaning and maintenance − identification of other hazards that the workers may be exposed to (i.e. hot water and steam exposure, electrical arc flash protection, welding, chemical exposure protection) Note: Although welders cannot wear typical flame resistant workwear, there are now welding garments that meet the standards of NFPA 2112 and CGSB 155.
The size and duration of the flame that results from this ignition is determined by the amount of fuel available, the efficiency of combustion, and the environmental and physical characteristics of the site of the flash fire or explosion. The temperatures attained by flash fires have been estimated to range from 550 to 10500 C, although higher temperatures are believed to occur. Even the lowest estimated temperature exceeds the temperature at which most regular clothing fabrics burst into flames.
This ensures the workwear will meet the following standards:
• A high level of flame resistance – should not ignite easily when exposed to a flame or continue to burn after the flame is removed;
• A high degree of insulation – should provide a barrier or insulating layer against exposure to heat
• Excellent fabric integrity – it should not melt or shrink; and
• Contain anti-static properties – the fabric should not act as an ignition source, i.e. static electricity. ( Tip: Inappropriate clothing around fire and explosion hazards includes untreated or light cottons, polyester, nylon and polycotton blends, (nylon is particularly bad!)
• Clothing worn underneath an outer layer of FRW should be made from fabrics that will not shrink or melt under exposure to heat. This applies to any article of clothing including pants, shirts and underwear. These fabrics include: Flame resistant fabrics − leather − wool − rayon − linen − cotton
FR clothing is unique because when exposed to high heat and flame for short periods of time, it does not burn, it does not melt, and it shields the clothing worn beneath it from the intense heat of the flame. FR fabrics are either inherently flame resistant — the fibres are of a material that itself does not burn — or are made of materials that undergo some type of treatment so that they are made non-flammable. Wool and leather are two naturally flame resistant materials that are appropriate in some work situations. While natural wool is not entirely non-flammable, it is self-extinguishing and therefore has some inherent flame resistance.
Most of the clothing fabrics traditionally used for outerwear are inappropriate for use around flash fire and explosion hazards. Untreated cotton, polyester, nylon, and polycotton blends are such examples. Untreated cotton has a very low ignition temperature of approximately 250o C and burns intensely and rapidly. Untreated polyesters and nylons ignite easily (250 – 350o C) and melt readily. Nylon is also particularly prone to static build-up and is a recognized ignition source. Polycotton blends combine the worst characteristics of both polyester and cotton. Clothing worn beneath FR clothing and against the skin should be made of FR fabrics or natural fibres that do not melt. Appropriate natural fibres include wool, silk, and cotton.
The “inherent” fibers tend to be synthetics, and most begin as naturally occurring flammable substances (petrochemicals), not fibers. Humans must intervene, using chemistry, to engineer the fiber and the FR properties within it. Similarly, most “treated” products begin as naturally occurring flammable substances (usually cotton or other cellulosics), so nature has already taken care of the fiber portion, and humans get involved to engineer the FR.
The word inherent was not originally a textile or FR term. Its definition varies slightly from source to source, but the common thrust is “by its very nature, built-in, implicit,” while “treated” is usually defined as chemical engineering to impart properties not previously present. Nature provides very few FR fibers, the most well known of which is asbestos, which is obviously not in common use in protective apparel in North America today.
First, fabric. Natural fibers such as cotton and wool will not burn right away when faced with fire. Some FR options are made from these materials. Some people have mistaken a paragraph prohibiting the use of these materials in non-flame resistant clothing to apply to flame resistant. A recent change to NFPA 70E called a Tentative Interim Amendment (TIA) has stated now clearly that the prohibition to cotton nylon blends refers to non-flame resistant materials, not to the new cotton nylon blends like Indura UltraSoft. Rayon along with nylon, polyester and acetate as materials that melt. Rayon is actually synthetic cellulose (like wood pulp or cotton) and does not melt. But if rayon is not flame-retardant treated, it can readily ignite thus its prohibition in the arc. If flame retardant treated, it can work very well in the electric arc and provide more comfort to the materials it is blended with. Don’t forget about employee comfort either. If people are comfortable wearing clothing, they’re more likely to wear it correctly. Look at the weight, thickness and stiffness of fabrics. Stiff fabrics can be uncomfortable and impede movement, while thick fabrics might make workers too warm in hot work environments.
Ensure that your company’s selection of flame resistant workwear is based on the following principles: • The use of hazard assessments to identify the need for flame resistant workwear. • An evaluation of available flame resistant workwear to determine those suitable for the hazards identified on your site. • The development of specifications for purchasing flame resistant workwear. · The use of a hazard assessment to determine other hazards that the worker’s clothing needs to protect against (e.g. hot fluids, electrical arc flash).
Conduct Hazard Assessments The wearing of fire resistant workwear should be considered as the basic standard for work in and near all oil and gas facilities. Any facilities or locations where oil or gas could be present can have an associated risk of flash fires. Take the following steps to identify the specific hazards that may require the use of flame resistant workwear for all other situations: • Determine the type and magnitude of hazards on your worksites. • Decide whether other control measures (e.g., engineering controls, administrative controls) can reduce hazards to an acceptable level. • Determine the level of protection needed to protect workers against the identified hazards. • Determine if there is a need for garment decontamination. • Determine if there are any ergonomic (e.g., restricted movement) or environmental constraints (e.g., temperature extremes) to using flame resistant workwear on your sites. • Compare the risks and costs of each option (e.g., engineering controls, administrative controls, flame retardant workwear). • Select and implement the best option or options.