PROTECTIVE CLOTHINGS AGAINST ELECTRICAL ARC THERMAL EFFECTS
DANGERS OF ELECTRICAL ARC
Electrical arcs can produce the highest temperature on earth (10.000 – 20000 oC). This is four times hotter than the sun. All known materials melt at that temperature.
As a result of Arc radiance, erupting gas and air can spread melted metal for long distances and laud noise up to 140 dB can cause permanent hearing loss.
Another physical reaction in the progress of Arc is pressure. Huge pressure about 1.400.000 kgf/m2 is pressurized on the chest of the individual who exposed to the Arc radiance and this may destruct the one’s clothing. Arc radiance can ignite the clothing within half or 1 meter away. If the clothing of the individual melts, covered parts may cause worse burns than the naked body parts exposed.
As a result, electrical arc can generate energy in extremely dangerous levels, can cause fatal burns. High majority of the ones who went to the hospital in case of an electrical accident is not from electric shock, but electrical arc accidents. High degree burns and deaths as the result of these accidents are because of the ignition and burning of the clothing which are not fire retardant.
WHO IS AT RISK?
- CAR MAINTENANCE SERVICES
- CHEMICAL FACILITIES
- FOOD PROCESSING FACTORIES
- PAPER AND PULP FACTORIES
- PETROL RAFINERIES
- SHOWROOMS – SHOPPING
THE PROPERTIES OF GARMENTS PROTECTIVE AGAINST ELECTRICAL ARC
Acetate, nylon, polyester, silk or mix of these garments must not be worn in dangerous occupational environments. In places where the risk of burning and flaming risk is present, garments made of flame retardant fabrics must be used. Flame retardant fabrics are named in two different classes by their heat insulation type.
- Flame retardant Fabrics:
Cotton, cotton/polyester mix, cotton/polyamide mix fire retardant fabrics will not lose their flame retardant properties up to specific time of wash. There are 50-100-150 times washable fabrics if the instructions of the manufacturer are followed.
- Inherently flame retardant
Some fabrics which are glass fiber like Aramid (meta-aramid or para-aramid) viscose fr are inherently flame retardant. They will not lose their fire retardation after many washes. But, they are two or three times expensive than chemical finished fabrics.
REGULATIONS AND STANDARDS
IEC 61482 1-1 and IEC 61482 1-2 standard has been published by IEC to define test methods for the garments and materials used in these heat and fire retardant garments which are for the workers who are exposed to Electrical Arc.
IEC 61482 1-1: is to measure the Arc Thermal Performance value of the layer system of the garment. 8 kA Electric arc is applied in 120 degree angles from three different spots for 167 ms. Heat increase values are recorded by a calorimeter behind the material. These values are transferred on a table and a curved line is drawn.
Test result must show that %50 of these measured values must be below these values.
IEC 61482 1-2( EN 61482 1-2): is published if the protection is provided or not against heat produced by Electrical arc according to safety requirements for lowest and highest levels defined in the standard for Entire garment and fabric layers system. Electrical ar is applied from 30 mm for 500 ms. Heat increase values are recorded by a calorimeter behind the material. These values are transferred on a table and a curved line is drawn.
Melting: Not allowed.
Burning: 5 seconds or less.
Hole: May be spotted on outer layer, max 0,5 cm is allowed for Inner Layer
Heat transmission values: All measured values must be below Stoll curve.
In both standards exposed energy value is set forth as 423kWs/m2. However IEC 61482-1-1 standard, which tests higher level of electrical arc, must not be seen as a better test method than IEC 61482 1-2. Because IEC 61482 1-1 is applied in an open environment where arc energy spreads through the air and also time of the exposure of the arc is lower than the other standard.
In IEC 61482 1-2, for level 2 test is applied for 7 kA in a closed box where arc is created and applied on the material, energy do not spreads. All energy directly penetrates the material. Test result evaluation is more comprehensive and longer electrical arc energy is applied. Consequently, IEC 61482 1-2 standard require more criteria than IEC 61482-1-1 certification and conforming the standard conditions are more difficult.
PROTECTIVE GARMENTS AGAINST ELECTRICAL ARC
Our ELECTPRO series garments as IST Ltd. Co. are certified as per Personal Protective Equipment directive; CE marked and successfully completed all EN 61482 -1-2 standard tests.