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How to select heat and flame protective clothing

Hydrocarbon Engineering,


They say ‘variety is the spice of life’ and when choosing anything a few different options are always welcomed. Choosing heat and flame protective garments to keep an employee safe is no different, however, fully understanding the difference between those options is absolutely crucial.

Flame resistant or retardant?

At the moment there is no clear distinction between the terms ‘resistant' and ‘retardant’, often leaving some buyers and end-users puzzled. Currently the CIRFS (European Man-Man Fibres Association), the representative body for the European man-made fibre industry, is attempting to create an official definition for the various combinations of terminology using resistant, retardant, inherent or treated in the name to clear up confusion. As a rule of thumb, the following definitions are widely accepted:

Flame resistant fabric and flame retardant are two terms that are used to describe a material that is self-extinguishing after removal of an external ignition source.

The distinction of inherent versus non-inherent fibres of fabrics, is whether the flame resistant or retardant properties are intrinsic to the polymer or fibre properties or whether a flame retardant or resistant chemical treatment applied somewhere after the fibre production. The flame resistance of a fabric is primarily a consequence of the properties of the fibre. Different yarn properties and fabric construction may contribute to increased flame resistance.

Inherent or coated protection?

When a fabric offers inherent protection, this is because it is manufactured with fibres, such as Nomex®, whose intrinsic structural properties make them naturally flame resistant. Because the properties are part of the structure, they cannot be washed out or removed by cleaning processes, wear and tear, and will continue to offer the same level of protection throughout the garment’s lifetime. The advantage of these types of protective fabrics is that the performance is robust despite the probable non-observance of the manufacturer’s cleaning instruction.

Non-inherent fabrics, sometimes known as coated FR or coated flame retardant fabrics, use a chemical treatment to achieve protection. The treatment chemicals are frequently ‘activated’ by intense heat, producing char and gases that inhibit combustion for a certain time. The limitations of flame retardant treated fabrics are that the added chemicals may be affected or removed by external factors such as washing, exposure to heat or exposure to other chemicals. The non-inherent fabrics are limited in that the heat and flame protective properties are maintained for the indicated wear life, i.e. for up to an indicated maximum number of cleaning cycles. However, this will only stay true as long as the user adheres strictly to the manufacturer’s cleaning instructions, otherwise there is risk of damage to the flame protective properties, potentially putting the wearer at risk.

European legislative requirements

The end goal of the garment is to offer thermal protection to the wearer. The garment should not burn, melt or disintegrate on exposure to flame throughout its lifetime and it should provide the required level of thermal protection consistent with the potential risk to which the wearer might be exposed. Before being placed on the EU market, garments must undergo specific tests and surpass a set level to ensure the wearer will be adequately protected. Under the EU legislative framework, the user, to be effectively protected by PPE must ensure, based on the first directive, to have conducted a risk assessment to determine the appropriate level of protection required, and purchase PPE compliant with the second directive:

  • Directive 89/656/EEC “Minimum Health and Safety Requirements for the Use by Workers of PPE” – known as the PPE ‘Use Directive’, which sets down the employer’s obligations towards health and safety of workers through a risk analysis and assessment, free of charge supply of appropriate PPE and training.
  • Directive 89/686/EEC “Approximation of the Laws of Member States relating to PPE” – known as the PPE ‘Product Directive’, which specifies the procedures for the placing on the market of PPE from its manufacture and certification that it conforms with the basic requirements to protect users of PPE.

The Product Directive brings together PPE covered into three distinct groups and whilst the Directive does not explicitly define these three groups into categories, it is common practice to use the terms category I, II and III respectively.

  • Category I: PPE of simple design and assumes that the user can access the level of protection against gradual risks, which the user can identify in good time, for example gardening gloves and sunglasses.
  • Category II: PPE that is neither simple nor complex but is considered intermediate design. This category provides intermediate level of protection.
  • Category III: PPE of complex design and that is intended to protect against mortal danger or against dangers that may seriously harm a person. The design assumes the user cannot identify the risk in sufficient time. This would include heat and flame protective garments.

In addition to this, PPE placed on the EU market must also carry CE marking. This symbol implies the conformity to all provisions of the relevant directives. Manufacturer’s information is also required to be supplied alongside the PPE and forms an integral part of assessing the conformity of an item of PPE. When choosing thermal protective clothing, one will come across a variety of standards. It is important to understand what these standards mean and also to have an idea of the testing that is behind achieving the standard. Some of these key standards are outlined below:

  • EN ISO 15025 in conjunction with EN ISO 14116: limited flame spread materials, material assemblies and clothing.
  • EN ISO 11612: protective clothing — clothing to protect against heat and flame.
  • EN ISO 11611: protective clothing for use in welding and allied processes.
  • IEC 61382-2 (draft EN 61482-2): live working – protective clothing against the thermal hazards of an electric arc.

Importance of ‘wearability’

There are factors other than safety that determine the effectiveness and ‘wearability’ of protective apparel, namely comfort and appearance. A responsible garment manufacturer will offer design assistance so that ergonomic needs can be translated into wearer benefits, providing protective work wear that is as attractive and comfortable as street wear whilst still meeting stringent protection standards. Comfort is not a luxury, but allows for more efficient working and increased attention during hazard work. There are two basic characteristics that have an impact on a wearer’s comfort and that can be measured objectively.

  1. Garment weight: the weight of a garment can help or hinder performance for the wearer and the type of fabric being used in the construction (i.e. is it a fabric with inherent flame resistant properties or is it a coated fabric), can have implications on the overall weight.
  2. Moisture management: a criteria of moisture management is the evaporation of moisture or perspiration from the skin through the fabric structure. The Sweating Guarded Hotplate test method (ISO 11092) measures the resistance of a material to let water vapour through, which is expressed as Ret (water vapour resistance in m2.Pa/W). A fabric’s moisture management performance is also influenced by its air permeability, the capacity to let air pass through (tested according to ISO 9237). Air permeability (expressed in litre/m2/sec) is an important measure of comfort, because it is a measurement of the air moving through a fabric and around the skin, leaving a dry feeling on the wearer’s skin.

Garment design is also an important element that has a direct influence on moisture management and overall comfort of the wearer and must be considered when specifying an appropriate PPE and its supplier.

Relationship with the supplier

Whether buying directly from a garment manufacturer or a distributor, a reputable organisation will be able to offer advice on the type, style and protective properties of a garment to ensure the best balance between comfort and protection based on the understanding of hazards and work practices.  Depending on each buyer’s requirement, an extensive choice will be offered from existing ranges, or bespoke garments may be able to be developed to meet specific needs. Ensuring garments are manufactured to the required standards is essential. For peace of mind, work with a garment manufacturer or supplier that has the British Safety Industry Federation’s Registered Safety Supplier mark, the CE mark or is a member of the Nomex® Partner Programme.

By understanding exactly what to look for, the different standards the garments must adhere to and the various types of protection available when choosing heat and flame protective garments, not only will workers be protected properly in life threatening situations, but buyers will be completely ‘in the know’ about what to expect from garments.


Written by Elaina Harvey, protective clothing and Nomex® specialist, DuPont.

Edited by Katie Woodward

Read the article online at: https://www.hydrocarbonengineering.com/special-reports/04112014/how-to-select-heat-and-flame-protective-clothing/


 

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