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When standard fluorescent tubes are accidentally broken, they may shatter, with dangerous shards of glass – made more dangerous still by sometimes toxic phosphor coatings – showering over nearby people. Where such tubes are used near foodstuffs in shops, retail outlets and supermarkets, the glass fragments can fall into the foods themselves. How to prevent this danger? The answer is to coat fluorescent tubes with a special material that contains the fragments if the lamp is broken. The standard to adhere to is IEC 61549, as James Hunt reports:
The risk of personal injury, potential cost of litigation and the impact of cleaning the mess up, means that fragment retention lamps manufactured to the IEC 61549 (BS EN 61549) standard, which came into effect in April 2010, provide a cost saving benefit to many businesses and organisations.
What is IEC 61549?
There has been relatively little regulation of shatterproof lamps for fragmentation retention until the advent of IEC 61549, which is the highest standard to which shatterproof lamps can be coated. It is now the recognised industry standard for such lamps.
The standard demands that all fragment retention fluorescent lamps (FRLs) contain 100% glass fragments from a minimum horizontal impact height of 4m. The polymer coating should also meet a 650ºC glow wire test demonstrating good thermal resistance. Effectively, the coating will not catch fire.
IEC 61549 also requires all shatterproof lamp coatings to have a service life of at least 16,000 hours when operated with high frequency control gear. This standard also requires all coated lamps to have an easily identifiable single band. IEC 61549 - 4.2.1 Lamp Marking - requires this band to identify the lamp as a fragment retention type. 'It shall be legibly and durably marked:
a) lamps suitable for open and enclosed luminaries shall be marked with one visible band/ring 3mm minimum width applied around the lamp within 150mm of one lamp cap, or
b) lamps ONLY suitable for open luminaires shall be marked with two visible bands/rings 3mm minimum width and spaced between 3mm and 10mm apart applied around the same end of the lamp within 150mm of one lamp cap.'
Single band FRLs have a higher temperature resistant coating applied to them. They can be used in most applications and cover the widest choice of lamps including 16mm diameter T5 high output.
The materials:
The UV stable coating material, such as fluorinated ethylene propylene (FEP) provides glass fragmentation protection because it contains the broken tube glass and phosphors etc if a breakage occurs. The FEP coating operates reliably up to (and above) 200°C, and also at the low temperatures typically found near food freezers, so it is an ideal material to protect fluorescent tubes sited at or near food and beverage production and the food retail sector. Importantly, such coatings also help prevent breakage during routine maintenance.
Other fragmentation protection materials include PET, ITUV and RT395, but FEP is compliant with IEC 61549.
IP65 light fittings:
Where there is a risk that lamps might be sprayed with water or be susceptible to dusts, IP protection might be needed - typically IP65. However, to provide such ingress protection, yet with good light transmission, glass is required, so there are also situations where shatterproof lamps should be fitted to IP65 ingress protection rated luminaires.
This is not a problem with lamps complying with the requirements of IEC 61549.
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