Mirey Bonfil
Personal Safety Division Application Engineer
3M
Works performed outdoors and walkways are very high in number in the cement sector. Use of reflective strips according to EN ISO 20471 standard, gains importance to improve visibility of trucks and bulk trailers entering and exiting from/ to packaging unit and raw material units and of the workers during evening hours. Although, the rate of using reflective strips to improve visibility has risen in Turkey, unfortunately there are still ones who indicate only grey stripes as reflective in our country.
While the stopping distance of a vehicle traveling at 50 kph is 58 meters upon sharp braking, the stopping distance when traveling at 95 kph is 170 meters. The general idea that wearing white clothes to improve visibility in the evening is not accurate. While a driver can recognize a person in white at 64 meters, one can recognize a person who wears suitable retroreflective material from a distance of 230 meters. Therefore, wearing suitable reflective material is important in terms of occupational safety.
Reflective materials are divided into two groups in terms of their production technology:
1- Glass Beads
2- Microprismatic
While both structures can satisfy EN ISO 20471 high visibility standard, microprismatic reflective materials provide higher visibility due to their internal structure. However, reflective materials employing glass beads structure gives a softer feeling and acts as if integrated with the textile garment. Both production techniques have their own advantages and disadvantages. Decision shall be made on the choice of reflective material of either production technology by considering operating environment and conditions.
Particularly, reflective materials worn by workers who perform raking in cyclone, work in furnace area and do welding work shall conform to EN 469 standards in terms of fire resistance and such shall be documented.
Users of reflective clothes generally have two complaints. The first one is the degradation of visibility and/or year and break down of the reflective material when washed. When reflective materials are tested for EN ISO 20471 standard, they are subjected to various tests such as EN ISO 6330 Domestic washing, EN ISO 31752-2 dry cleaning etc. In the result of these tests, certification is made as the reflective material withstands washing 20 times or 50 times in a domestic washing machine at 60°C. The greatest criterion here is whether the reflective strip can satisfy 100 cd/lux value by being measured with special devices upon being washed each time, pursuant to EN ISO 20471 standard. If the value falls under 100 cd/lux value when measurement is done, EN ISO 20471 certificate of such reflective material becomes invalid. Therefore, washing frequency and washing conditions shall be separately studied and selection shall be done accordingly by the employers and occupational health and safety engineers, when selecting the reflective strip. Also, as another problem, with tear and damage occurring in the result of washing, degradation of visibility level will occur since the integrity of the reflective material is impaired and as a consequence risk of accident will increase. The second complaint of the workers is with regard to sweating particularly in areas where reflective strips are attached. The solution to eliminate this complaint is to use segmented / striped reflective strips which have become widely used abroad and recently been recognized in our country too. With the striped reflective material, air passage will be better and this will offer a more comfortable work environment to the worker. Also, since the integrity will not be impaired when viewed from a distance, no additional risk of decreased visibility will occur although they are striped.
Choosing the right product is as important as placing the reflective material correctly. Particularly, when the reflective stripe only installed at the waist section in case of workers lifting and lowering loads/boxes, the worker will not be visible causing additional risk. Therefore, excluding Class 2 and Class 3 requirements indicated in EN ISO 20471 standard (Table 1), design guidance provided by the standard shall be taken into consideration.
Reflective materials can be applied to the fabric both by stitching and by transfer (applying pressure and/or heat on it). This is completely dependent on the product and capacity of the manufacturing company.
Another aspect is the difference between fluorescent and retroreflective. All garments with conventional color, reflect the photons of the visible beams emitted on the garment and absorbs all of the remaining photons. Fluorescent colors reflect the photons of visible beams emitted on the garment, absorbs photons with short wavelength and reflect them back with a longer wavelength. In other words, UV light is brought to the visible beam wavelength. However, visibility of fluorescent colors is higher in morning hours compared to evening hours. Retroreflective materials reflect the light emitted on them and reflect them back again. Therefore, evening visibility offers higher efficiency compared to morning. Therefore, presence of both retroreflective and fluorescent color strips on the garments of the workers is recommended. Thus, visibility will be improved both in the morning and in the evening, thus, accident risk resulting from lack of visibility will be decreased.
