Industrial and production operations are prime environments for the potential build-up of combustible gases, liquids, dust and other ignitable sources. Fire and explosion hazards can occur in that environment. Working in a hazardous environment requires portable task lighting such as headlamps and flashlights that are intrinsically safe to keep personnel and property safe from explosion and fire.
A device termed intrinsically safe is designed to be incapable of producing heat or spark sufficient to ignite an explosive atmosphere. Maintaining intrinsic safety requires that the light be used properly and not tampered with so the intrinsically safe capability remains intact.
An explosive atmosphere is defined as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapors, mist or dust in which, after ignition has occurred, combustion spreads to the entire unburned mixture.
The NFPA Publication 70, NEC, and CEC define three categories of hazardous materials that have been designated as Class I, Class II, or Class III. The Classes define the type of explosive or ignitable substances which are present in the atmosphere such as:
Class I locations are those in which flammable vapors and gases may be present.
Class II locations are those in which combustible dust may be found.
Class III locations are those which are hazardous because of the presence of easily ignitable fibers or flyings.
Each of the three Classes, discussed above, is further subdivided into two Divisions, Division 1 or Division 2. The Division defines the likelihood of the hazardous material being present in a flammable concentration. These Divisions are defined as follows:
Division 1: In which ignitable concentrations of hazards exists under normal operation conditions and/or where hazard is caused by frequent maintenance or repair work or frequent equipment failure.
Division 2: In which ignitable concentrations of hazards are handled, processed or used, but which are normally in closed containers or closed systems from which they can only escape through accidental rupture or breakdown of such containers or systems.
(The groups include but are not limited to)
Group A : Acetylene
Group B: Hydrogen, Butadiene, Ethylene Oxide, Propylene Oxide
Group C: Ethylene, Cyclopropane, Ethyl Ether
Group D: Propane, gasoline, naphtha, benzene, butane, ethyl alcohol, acetone, methane
Group E: Combustible metal dust including aluminum, magnesium (Div. 1 only)
Group F: Combustible and carbonaceous dusts including coal, carbon black, coke
Group G: Dusts not included in E and F including wood, plastics, flour, starch or grain dusts
Several different agencies develop standards for intrinsic safety, and evaluate products for compliance with standards. Agencies may be run by governments or may be composed of members from insurance companies, manufacturers, and industries with an interest in safety standards. Certifying agencies allow manufacturers to affix a label or mark to identify that the equipment has been designed to the relevant product safety standards. Examples of these agencies are:
The ETL Listed Mark is proof of product compliance (electrical, gas and other safety standards)to North American safety standards, including UL, ANSI, CSA, ASTM and NFPA standards
The European based ATEX directive defines the equipment and work environment that isallowed to function in an explosive atmosphere. The regulations apply to all equipment intended for use in explosive atmospheres, either electrical or mechanical, including protective systems. The directive covers a large range of equipment where a potentially explosive atmosphere may be present.
CE mark is the official marking required by the European Community for products that will be sold, or put into service in the European community. The product fulfills all essential safety and environmental requirements for the product's intended use, as they are defined in the European Directives, primarily ISO Standards.
The IECEx is the International Electrotechnical Commission system for the certification to standards for electrical equipment for explosive atmospheres.
Mine Safety and Health Administration requires that portable battery operated lighting be designed and tested to not pose an explosion hazard in mining operations.