Portability in Explosion Proof Lighting Equipment|
Article-December 2012 By Larson Electronics.com
Larson Electronics Portable Explosion Proof Metal Halide Light
Explosion proof lighting forms an integral part of equipment safety when operating in areas that have been deemed as being hazardous locations. The presence or potential presence of flammable or explosive gases, vapors and materials in the hazardous workplace presents a serious threat to the safety of workers in that area, and the structures, goods and health of nearby private residences, commercial businesses, and the people in these other nearby areas. In many cases, the presence of flammable materials is a normal part of operations and an unavoidable necessity. As a result, preventing the ignition of these materials becomes a critical part of maintaining safety while they are present.
In most hazardous locations, explosion proof or intrinsically safe lighting equipment is integrally installed and part of a comprehensive approach to safety that benefits from regular inspection and maintenance. Such lighting is generally well suited to the environments at hand and performs quite well. Additionally, the wiring, controls, and power supply for such systems is likewise matched through classification to such lighting systems in order to meet compliance and help provide the highest degree of safe operation possible. The problem however, is that it is not possible to utilize such integrally installed lighting systems in all hazardous locations. In locations such as production lines, refineries and processing areas where work is commonly performed on a routine basis that deals, produces, or otherwise causes interaction with hazardous materials, it is of course more practical to utilize integral explosion proof lighting. Other locations where work is not so routinely performed but the potential for ignition exists, present new challenges for the workers who must enter them.
Any work area can become a hazardous location if flammable gases or vapors are present. The structure or location need not be the usual control area or work floor within a building in order to require explosion proof protection. Items such as storage tanks in refinery operations, sealed rail car tanks, ship holds and containers in the commercial marine transport industry, paint spray booths, power plants and the like all hold the potential for the presence of flammable materials and atmospheres when working within or nearby to them. Servicing, maintenance and repair of such containers and structures often requires worker ingress, and although the contents may be removed, flammable vapors and gases may remain which can still potentially be ignited by the electrical tools and lighting workers bring with them. As a result, it is necessary to provide portable illumination which holds the same explosion proof approval and certification as normally integrally mounted lighting.
Portable explosion proof lighting is constructed similarly to fixtures designed for permanent mounting, but there are a couple notable differences that must be taken into consideration if it is to be utilized safely. Since such lighting is portable, providing power for the lighting will require external cords and connections rather than the protected conduit and wiring permanently mounted fixtures use. This presents the first important difference that can cause potential problems if not fully understood. The primary problem with such cords and connections is that every time the device is connected and disconnected, such as when plugged into an outlet, it is possible for arcing and sparking to occur at the point of connection. As a result, it is usually safest to connect the device to a properly rated explosion proof extension cord, then connect the cord to an outlet outside of the hazardous area. In this way the operator completely removes the potential for sparking that could ignite a flammable atmosphere.
Another way to safely supply power to your portable lighting is to utilize specialized receptacles, plugs and switches which are designed to allow connection and disconnection within the hazardous location. Such plugs, receptacles and switches must also meet classification for the area they are to be used within, the same as the lighting or devices connected to them. These connectors and switches are typically sealed units which utilize deeply recessed sockets and a twist lock operation to protect against sparking. The deeply recessed sockets provide better sealing and less potential for sparking, and the receptacle itself does not become full energized until the plug is fully seated and twisted into position, locking the plug and then energizing the receptacle. Receptacles equipped with a switch provide a higher degree of protection by allowing operators to make all their connections while the receptacle is not carrying current. Once everything is securely connected, the operator simply turns the switch to complete circuit.
Another important consideration is the durability of the portable lighting in question. Due to its very nature, portable lighting is subject to a great deal more abuse and rough handling than a typical permanently mounted fixture. Portable light towers, pedestal lamps and trouble lights and work lamps are prone to being knocked over or dropped as well as receive accidental shocks and impacts from the high amount of activity occurring around them. The problem here is that although a light may be properly classified, it is possible to damage the unit, or even shatter a bulb or lens, which can then result in an extremely unsafe condition as the hot parts of the lamp can be exposed to the flammable outside atmosphere. This potential is greatest with explosion proof lights which rely on incandescent or HID bulbs for their light output as both these lamp styles utilize a fragile glass bulb which is prone to breaking or shattering under heavy impacts.
One great way to avoid potential shattering or exposure of hot lamps to hazardous atmospheres is to utilize newer portable explosion proof LED lamps. These lamps run far cooler than HID or incandescent lamps, and are much more durable. LEDs have no fragile glass or wire filaments to break or shatter, and their solid state design can withstand substantial shocks and impacts without any serious degradation in performance or protection.
The use of portable lighting within hazardous locations has grown significantly over the last decade as regulations continue to tighten and OSHA pays ever closer attention to operations in potentially hazardous industries. By paying an extra bit of attention to how this portable lighting is chosen and operated, workers can maintain safety and compliance while reaping all the benefits that portable explosion proof lighting holds.