Home >> News >> Industry News
An explosion proof LED flood light is a directional luminaire capable of producing a controlled beam of light for industrial area and task lighting. These luminaires are installed to illuminate outdoor environments where fire or explosion hazards may exist due to the presence of flammable gases or vapors, combustible dusts, or ignitable fibers or flyings. Outdoor areas classified as hazardous locations can be found in chemical and petrochemical processing facilities, oil refineries, drilling rigs, offshore oil platforms, marine loading and fuel transfer terminals, off-shore and dockside installations, tank farms, pipeline pumping stations, waste and sewage treatment plants, coal preparation plants and coal handling facilities, and outdoor paint spray facilities. Electrical equipment, which may produce arcs, sparks or high temperatures, can ignite an explosive atmosphere. The electrical installation therefore must be protected to prevent the ignition of potentially explosive atmospheres or materials outside the equipment. An explosion proof LED flood light is designed in a way that it will never give rise to explosion risks. Yet, it must be robust enough to perform in harsh environments that are typical of classified lighting applications.
Hazardous areas are locations where explosive concentrations of flammable gases, vapors, dusts, or ignitable fibers or flyings may exist in the atmosphere. In many countries there’re established systems that classify these areas and set rules for the types of luminaires that may be installed in each of the classified areas. In the United States the National Fire Protection Association (NFPA) published the NFPA 70, National Electric Code (commonly called the NEC) which defines classes and divisions of hazardous locations as well as requirements for electrical system design and equipment used in such locations. In Canada the Canadian Electrical Code (CEC) adopted the same system. Luminaires that are designed to be used in hazardous locations as classified by NEC or CEC must be third-party certified to UL 844 “Luminaires for Use in Hazardous (Classified) Locations” or CSA C22.2 No. 137 “Electric Luminaires for Use in Hazardous Locations”. The ATEX Directive which is a CENELEC (the European Committee for Electrotechnical Standardization) standard defines the criteria and requirements for the construction, testing and marking of electrical equipment intended for use in potentially explosive atmospheres within the European Union. The IECEx System of the International Electrotechnical Commission (IEC) on the other hand is an international system for certification of equipment for use in explosive atmospheres. Both IECEx and ATEX align with the same standards and use a Zone system to classify hazardous locations.
Explosion proof flood lights rely on the use of explosion proof enclosures or dust-ignition proof enclosures to eliminate the source of ignition or likelihood of explosion. In Class I hazardous environments or ATEX/IECEx Gas zones flammable gases and vapors are expected to get inside the enclosure. A luminaire rated for use in these hazardous locations is built on the concept of explosion containment. The light engine and electrical components are enclosed by a robust housing which is capable of withstanding an explosion of a specified gas or a vapor that may occur within it and of keeping an internal explosion within the explosion proof enclosure from escaping outward and igniting the surrounding hazardous gas or vapor.
The luminaire enclosure must be strong enough to contain an explosion within and provide a flame path for the passage and escape of burning gas resulting from the internal explosion. The flame path is designed so that the hot gas created inside the luminaire during an internal explosion is cooled below the ignition temperature of the surrounding explosive atmosphere.
In the case of luminaires designed for use in Class II and III hazardous environments or ATEX/IECEx Dust zones, the explosion protection is accomplished to enclose the light engine and electrical components in a manner that excludes combustible dusts or ignitable fibers and flyings and prevents arcs, sparks, flashes, or heat otherwise generated or liberated inside of the luminaire enclosure from igniting the surrounding atmosphere.
Flood lights installed in all hazardous environments should maintain an operating temperature that is lower than the ignition temperature of the surrounding explosive atmosphere. The operating temperature in this context refers to the temperature of the luminaire’s hottest surface that comes in contact with atmospheric explosion hazards.
Today’s industrial facilities are tasked with improving productivity and safety while reducing operating costs. The ongoing transition to solid state lighting enables human productivity, cost savings and new applications previously thought impractical or not even thought of. LEDs have many distinctive characteristics that lend them perfectly to hazardous location lighting applications that were previously the realm of HID and fluorescent lights. LED lighting allows for holistic optimization of all lighting application efficiency (LAE) factors for substantial energy savings beyond just improvements to light source efficiency. These LAE factors include optical delivery efficiency, spectral efficiency, and intensity effectiveness. In addition to a significant reduction in operating costs through energy efficiency and reduced maintenance, the reliability, durability and improved lighting quality contribute to an increase in productivity and safety.
Fluorescent and HID explosion proof lights have a lower source efficiency and LAE, and their physical and electrical characteristics create constraints of their use in hazardous environments which place high demands on the robustness of the lighting system. These glass enveloped light sources are fragile when mechanical shocks or vibrations occur. Greater explosion hazards can be present when HID sources such as metal halide and high pressure sodium lamps are used in hazardous environments. These light sources operate not only at very high pressures, but also at temperatures above 1000°C which can ignite the surrounding explosive atmosphere of any material composition when the glass envelop breaks and the hot quartz falls out of the fixture.
LEDs are low voltage devices that converts electrical power to optical power through electroluminescence. Their spark-free operation, solid state durability and semiconductor nature give them the unique ability to create explosion proof lighting systems with high performance, reliability and safety.
Explosion proofing lays a great emphasis on mechanical engineering. An explosion proof LED flood light is constructed with a rugged die cast aluminum housing which gives the luminaire. structural strength, heat sinking capability and corrosion resistance. A one-piece, die-cast aluminum door frame secures a high strength, impact resistant tempered glass lens to the housing to form the explosion proof or dust-ignition proof enclosure. For luminaires intended for use in Class I hazardous environments or ATEX/IECEx Gas zones, the enclosure must be built to resist the excess pressure created by an internal explosion. The explosion proof enclosure must withstand a hydrostatic test of four times the maximum internal explosion pressure without rupture.
The flame path between the housing and door frame must be sufficiently long and provide a controlled interstice to guarantee effective cooling of the burning gas and, preferably, exclude dust, flyings and fiber from the enclosure’s interior. A flood light can have multiple flame paths. Since the LED driver is often enclosed in a separate compartment or box for thermal isolation and ease of maintenance, the driver enclosure should be explosion protected.
