With the various levels of protection available, it is important to conduct some research before purchasing safety clothing because different industries have different requirements. By taking the various standards and factors into account, safety clothing can be designed so that it protects employees (or those affected by the activity) from the risks associated with the work activity.
Below you can find the fabrics which are often used to make disposable coveralls.
The global leading fabric in the disposable protective clothing industry is flash-spun polyethylene. In shorthand, the fabric is produced by mixing polyethylene with a solvent, pressurising it at high temperature and then extruding it through fine holes. During the extrusion process the solvent literally explodes or ‘flashes’ off, (hence the term flash-spun), leaving behind many fine polyethylene fibres which are then compressed into a flexible, dense sheet which combines the properties of strength, softness and liquid barrier (bearing in mind each of these terms is relative and subjective). It is also often described as ‘breathable’.
Its key competitor of the last ten years, microporous film, is a different, two layer construction, the inner layer being standard spunbonded polypropylene, and the outer being a microporous polyethylene film. This film has the structure of a sponge on a microscopic scale. There are no holes directly through it, but it consists of lots of tiny chambers, some of which interlock and overlap creating winding pathways through the fabric. This creates a fabric that combines the properties of strength, softness and liquid barrier (again bearing in mind each of these terms are relative and subjective). It is also often described, as we saw earlier, as ‘breathable’, though to what extent is uncertain.
SMS (Spunbound Melt-Blown Synthetic) material is a unique trilaminate material, of which there is a growing band of latter day variations such as SMMS, SMMMS or SMSMS. This, by contrast, really is breathable. A simple fabric-over-the-mouth test will readily demonstrate this and you can wear an SMS bag over your head and carry on quite normally all day long. SMS doesn’t have quite the same level of protection as spunbound polypropylene and microporous film combo, although – and this is important – it does still meet the requirements, and in many applications will provide perfectly adequate protection.
Globally, there are many different levels of protection used in working environments, but it is important to understand what levels of protection are available in terms of best practice internationally, and the standards to which the product protects to. In European standards the different levels of protection have been defined in terms of ‘Types’. Types relate to different groups of applications with similar properties – for example, whether they involve protection against dusts, liquids or gasses, and whether the liquid is in a strong spray or light splash form. The standards identify six Types to cover all eventualities – Type 1, Type 2 and so on, down to Type 6. In general terms Type 6 is the lowest protection level, namely “reduced liquid spray protection”.
A classic Type 6 application might be paint spraying, for example. There are so many variables in any individual application you care to name that it is difficult to be definite and specific about the parameters of any application. Hence all protective clothing recommendations come with a disclaimer stating that it is the user’s final responsibility to ensure the garment is suitable for the application.
Type 1 is the highest level protection being ‘gas tight’ suits – fully encapsulating suits which completely seal the individual against the environment. Type 2 is a similar construction but defined as ‘non-gas tight’, and requires a positive pressure to be maintained inside the suit by means of pumping air into it. In between the two extremes are various levels of liquid protection relating generally to the spray intensity and volume of liquid. The odd one out is protection against hazardous dry particles (that’s dust) and is defined as Type 5.
The European Types 1 to 6 should not be confused with the internationally recognised overall classification for Personal Protective Equipment (PPE), which in Europe is rated as classes. With Class 1 being ‘Simple’ products, relating to PPE not designed to protect against hazards and Class 3 being ‘Complex’ products, those designed to protect against hazards.
Bizarrely, and while not directly related to the particular subject discussed in this article, it is worth mentioning that the classification of individual fabric properties of garments, things such as tensile strength, puncture resistance, chemical permeation and the like, reverses the numbering system again so that the highest class is the highest protection level. In summary:
In overall Product ‘Classes’: Classes I to III The Highest Class number = Highest Protection
In application ‘Types’: Types 1 to 6, The Highest Type number = Lowest Protection
In fabric property ‘Classes’: Classes 1 to 5 or 6 (depending on the property), The Highest Class number = Highest Protection
So when choosing protective clothing the buyer needs to be aware of the international standards to which it complies and the protection it offers.
The garments most commonly used are those for Type 5 and 6 applications. Here the holes created by stitched seams are not, in most cases, critical, although the relative weakness of disposable materials means that poorly sized and/or poorly designed garments can result in problems when resultant stress on the seams opens up stitch holes, allowing ingress of harmful dusts or liquids. This is something users should bear in mind when considering very low priced garments. The major cost component of a disposable coverall is the fabric, and low prices are too often achieved simply by making the garment smaller and using less fabric – this can be an issue of safety as well as of comfort and durability.