AN ESSENTIAL GUIDE TO
FLAMEPROOF EQUIPMENT “We share the importance and essentials of the explosion and flameproof equipment”.
By Donovan Souvaris
01 FLAMEPROOF EQUIPMENT IN THE MINING INDUSTRY A BRIEF INTRODUCTION
06 MAINTENANCE AND SAFETY REQUIREMENTS OF FLAMEPROOF EQUIPMENT THE IMPORTANCE OF MAINTENANCE
08 APPLICATION OF FLAMEPROO LIGHTING EQUIPMENT AND ENCLUSURES LIGHTING IN UNDERGROUND MINES
11 CERTIFICATION CERTIFICATION
TESTS
AND CONCLUSION
HYTRONIC SA
What is flameproof Enclosure? Flameproof enclosure, means an enclosure for electrical machinery or apparatus that will withstand, when the covers or other access doors are properly secured, an internal explosion of the inflammable gas or vapour, Which may enter or originate inside the enclosure, without suffering damage and without communicating the internal flammation, (or explosion) to the external inflammable gas or vapour in which it is designed to be used, through any joints or other structural openings in the closure. So basically, Explosion proof enclosures are boxes or cabinets that contain electrical components such as plugs, knobs, sockets, switches, controls, etc. They help in preventing the internal explosions from spreading out in the ambient environment.
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Flameproof Equipment in The Mining Industry
Flameproof VS Explosion Proof Flameproof enclosures are used as protection on projects with IEC standards. Each of them, one by one, is factory tested to one and a half times the maximum pressures that are released in an explosion. Flameproof enclosures are firmly fixed with special devices so that they cannot be removed without the use of some sort of a special tool, or in some cases, multiple special tools. Explosion proof enclosures are individually factory tested to four times the maximum pressures that are released in an explosion. As a result, explosion proof enclosures are more heavily constructed than flameproof enclosures are. It is also acceptable to drill an explosion-proof enclosure in the field. Flameproof enclosures and Explosion-proof enclosures each have their own advantages and disadvantages. It’s all up to the user whether they like one over the other and it all depends on what job they need the enclosure for. However flameproof is the only method generally accepted to lighting and power installations, depending upon mechanical designs to prevent any explosion inside the case of apparatus of machines for igniting the atmosphere.
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Intrinsic Safety and Flameproof apparatus in Mines Intrinsic safety is a technique used to prevent explosions, which could be caused due to the sparking of electrical apparatus in hazardous areas such as mines. There are three components and all three together make a field device intrinsically safe - The primary device, such as the transmitter, needs to be intrinsically safe - The power for the device should come through the intrinsic safety barrier - The field wiring should not be capable.
Advantages of Intrinsic Safety - Eliminates the possibility of explosion - The least expensive and easiest to install of all protection methods - Ideal for low powerdevices - Little to no maintenance required - Accepted throughout the world - The same equipment satisfies the requirements for both dust and gashazards - The installation and maintenance requirements for installations safe apparatus are well documented and consistent regardless of the level of protection.
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Maintenance and Safety Requirements of Flameproof Equipment
Importance of Maintenance and Safety Requirements of Flameproof and Intrinsically Safe Equipment for Mines The maintenance of the integrity of the type of protection foreseen for the equipment has to be especially considered. Spare parts must be as per the documentation for the safety protection and assurance. For example, Coal mining is the important sector of any country ’s economy. In the coal mines, a flammable atmosphere may be present in the form of gas, vapour and dust and it is classified as a group. It is a statutory requirement that some safeguards are required to apply in electrical and electronic equipment to prevent ignition source from this equipment. It is possible only when proper, timely and cost-effective installation and maintenance is done. If proper maintenance is not done timely then there are lots of chances of improper function or creation of arc/spark from the Ex equipment which can cause for an explosion in the hazardous area. Maintenance of Ex equipment should always be done in the safe area only except for some equipment, if live maintenance is carried out, it should be specified in certificate or procedure declared by the manufacturer. Thus, continuous education and skilled training about the type of protection and its importance are required to the concerned manpower to minimize the risk of explosion from Ex equipment. 6
Maintenance of Flameproof Equipment There are several types of Ex d equipment is being used in the underground mines. These are mainly motor, light fixture, junction box (JB), control panel (CP), plug and socket, cable gland, stopping/ closing device, etc. The opening and checking of Ex d equipment in energised condition are not permitted in the hazardous area but if required, it should be done in the safe area only. A written permission is required from the concerned person for any repair/maintenance job in hazardous areas. The precaution includes replacement parts must be genuine and identical only and it should be certified and approved for use in a hazardous area. Any alteration is done without authorization invalidates the Type Test Certificate of Ex equipment and the end user is responsible for an explosion if it occurs after alteration. It is anticipated that each inspection model needs to be tailored to the specific requirements of a given site and all the explosion protection equipment are to be considered for maintenance. Various important points on the safety management of Ex equipment are required to minimize the breakdown for increasing the production. Equipment operation, proper maintenance schedule and handling ability of Ex equipment in a hazardous area is also vital. A safe, reliable, and convenient maintenance technique can enhance the safety of the underground coal mines. 7
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Application of Flameproof Lighting Equipment and Enclosures
Lighting in underground mines A characteristic of underground mining operations is that, as the workers move from the surface to the interior, the darkness becomes more complete, which is why lighting is a very important and fundamental factor. Therefore, in underground mines, it is vital to have safe and efficient lighting. Hytronic manufactures high optical performance lighting adapted to underground mines. whereby all these are certified light fixtures meet the highest safety standards and are explosion proof. Explosion hazard in underground mines involves the use of special lighting to avoid possible accidents. For example, in coal mines, firedamp concentration can be high, resulting in explosive atmospheres, where an explosion can be caused by mechanical or electrical sparks. Lighting standards help to ensure the safety of lighting installations in mines. With many years of experience in technical lighting, Hytronic has created luminaires which have been designed for use in hazardous areas. With low maintenance cost, easy installation, and maximum security, the luminaires are compliant with Atex. All Hytronic lighting was created especially for lighting in underground mines. It can also be used in other industrial facilities, both indoors or outdoors. 9
Ex d Enclosures: understanding the standards The primary function of an Ex d enclosure is to prevent the propagation of an internal explosion to the surrounding explosive atmosphere, and protecting the internal components from the environment, humidity, dirt, dust or water. With Ex d flameproof enclosures, it is critical that the flame path is not damaged. The external enclosure of any flameproof electrical equipment is designed to withstand an internal explosion. The enclosure joints, therefore, permit and control the resulting expansion of flames and hot gases – as these are relieved through the joints, preventing that explosion transmitting through to the external atmosphere. The relevant European (EN 60079-1) and International standards (IEC 60079-1) in addition to EN/IEC 60079-0 “General Requirements” apply. Most international, manufacturers and end users have to consult two Directives: 94/9/EC covers equipment and protective systems intended for use in potentially explosive atmospheres (ATEX) and is for the manufacturers of the equipment. For end users, Directive 1999/92/EC “Risks from Explosive Atmospheres” (December 1999) outlines and harmonises the minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres. 10
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Flameproof Ex d Closures Certification
Certification tests: Buyers of Ex d enclosures should also be aware of the certification tests involved. The tests to be performed are defined in EN/IEC 60079-0 (general requirements) and in EN/IEC 60079-1 for the type of protection “flame proof enclosure�, known as 'Ex d'. For all Ex d equipment, thermal tests are conducted to determine the maximum surface temperature of the complete equipment (enclosure and inbuilt parts) under maximum service conditions with a safety margin added. The additional thermal endurance of heat and cold (non- metallic enclosures or parts of enclosures) are tested and impact tests are always carried out on critical parts. The tests above or definitions made to prevent an electrostatic ignition source from becoming effective are also performed. For Ex d enclosures (EN/IEC 60079-1) additional tests that are normally carried out involve Reference Pressure, Overpressure and Flame Transmission. Additional tests are necessary, for example, for light transmitting parts made from glass or breather plugs. For more information as well as all your flameproof requirements visit www.hytronic.co.za.
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Contact Details: Corner Stanley & Max Street Knights Germiston 1401 010 040 8322 marketing@hytronic.co.za www.hytronic.co.za