Overview and definitions
The following classification and rating details are only meant to be a guide for quick reference. We make no claims to the accuracy of the information below. Explanation of these classes, divisions and atmospheres can be found in Article 500 of the United States National Electrical Code.
What is Intrinsically Safe (IS)?
What is Non-Incendive (NI)?
What communication products carry safety certifications?
Classifications
Certifying Agencies for Hazardous Locations Equipment
Servicing of Intrinsically Safe Radios
Communications equipment that is incapable of releasing sufficient electrical or thermal energy under normal or abnormal operating conditions to cause ignition of a specific hazardous mixture and air. The IS rating is required for equipment to be used in Division 1 environments.
Communications equipment that is incapable of releasing sufficient electrical or thermal energy under normal operating conditions only which cause ignition of a specific hazardous mixture and air. The NI rating is required for equipment to be used in Division 2 environments.
The following types of products may also be certified as Intrinsically Safe/Factory Mutual or Non-Incendive, when used together with approved radios:
Intrinsically safe and Non-Incendive approvals are classified by classes, divisions, groups and a temperature rating. These are further defined as follows:
Class: this can be defined as relating to the industry type in which the equipment will operate.
Classes range from Class I to Class III, where
Class I (gas or vapors):
Class II
Class III
| Class | European IEC, Cenelec, NEC 505 codes | N.A. NEC 500, CSA codes, UL® 913-88 Standards |
| Flammable Material Present | ||
| Continuously Present | Zone 0 | Division 1 |
| Intermittently Present | Zone 1 | Division 1 |
| Abnormally Present | Zone 2 | Division 2 |
| Gas & Vapors Present | ||
| Acetylene | Group IIC | Class I/Group A |
| Hydrogen | Group IIB | Class I/Group B |
| Ethylene | Group IIB | Class I/Group C |
| Propane | Group IIA | Class I/Group D |
| Methane | Group I | N/A |
| Dust Present | ||
| Metal | N/A | Class II/Group E |
| Coal | N/A | Class II/Group F |
| Grain | N/A | Class II/Group G |
| Fibers (All) | N/A | Class III |
Division: this can be defined as relating directly to the proximity of the risk. That is, is the hazardous mixture in direct contact with the environment (Division 1, closer proximity) or is it enclosed within a container or system or ventilated (Division 2, further proximity).
Group: this is the type of atmosphere and ranges from Group A through to Group G.
For detailed list of groups see below:
Group A Atmospheres
Atmospheres containing Acetylene gas.
Group B Atmospheres
Atmospheres containing Hydrogen gas.
| Group C Atmospheres | Chemical (Ethylene based) | |
| 2-nitropropane | Acetaldehyde | allyl alcohol |
| carbon monoxide | crotonaldehyde | cyclopropane |
| diethyl ether | Diethylamaine | epichlorohydrin |
| ethyl mercaptan | ethyl sulphide | ethylenimine |
| hydrogen cyanide | hydrogen sulphide | Morpholine |
| n-butyraldehyde | tetrahydrofuran | UDMH 1, 1-dimenthyl hydrazine |
| unsymetrical dimethyl ethylene | ||
| Group D Atmospheres | Chemical (Propane based) | |
| 1-butanol (butyl alcohol) | 1-pentanol (amyl alcohol) | 1-propanol |
| 2-butanol (secondary butyl alcohol) | 2-methyl-2-proponal | 2-methyl-l-proponal |
| 2-propanol | 3-methyl-l-butanol | acetic acid |
| Acetone | acrylonitrile | ammonia** |
| Benzene | Butane | di-isobutylene |
| Ethane | ethanol (ethyl alcohol) | ethyl acetate |
| ethyl acrylate (inhibited) | ethylene diamine | ethylene dichloride |
| ethylene glycol monomethyl ether | Gasoline | Heptanes |
| Hexanes | isobutyl acetate | Isoprene |
| isopropyl ether | mesityl oxide | methane (natural gas) |
| methanol (methyl gas) | methyl ethyl ketone | methyl isobutyl ketone |
| n-butyl acetate | octanes | pentanes |
| petroleum naptha* | propane | propylene |
| pyridine | styrene | toluene |
| vinyl acetate | vinyl chloride | xylenes |
* Saturated hydrocarbon mixture boiling in the range of 20-135 ° C (68-275 ° F). Also known by the synonyms benzene, ligroin, petroleum ether or naphtha.
** For classification of areas involving ammonia atmosphere, see Safety Code for Mechanical Refrigeration (ANSI/ASHRAE 15-1978) and Safety Requirements for the Storage and Handling of Anhydrous Ammonia (ANSI/CGA G2.1-1972)
Group E Atmospheres
Atmospheres containing metal dust, including aluminum, magnesium and their commercial alloys, and other metals of similarly hazardous characteristics.
Group F Atmospheres
Atmospheres containing carbon black, charcoal or coke dusts which have more than 8 percent total volatile material (carbon black per ASTM D1620, charcoal, coal and coke dust per ASTM D271) or atmospheres containing these dusts sensitized by other materials so that they represent an explosion hazard.
Group G Atmospheres
Atmospheres containing flour, starch, grain or combustible plastics or chemical dusts.
Temperature rating is probably the most important factor for IS portable radios. The temperature rating is a maximum temperature ( ° C) with an associated identification code.
The temperature rating means that where any hazardous mixture explodes or combusts at less than the stated maximum temperature, then the portable radio cannot be used in this environment. If units do not meet the temperature requirement then there is no basis for utilizing radios regardless of whether or not the units meet the other standards i.e. class, division and group.
| Identification Code | Maximum Temperature (° C) |
| T1 | 450 |
| T2 | 300 |
| T2A | 280 |
| T2B | 260 |
| T2C | 230 |
| T2D | 215 |
| T3 | 200 |
| T3A | 180 |
| T3B | 165 |
| T3C | 160 |
| T4 | 135 |
| T4A | 120 |
| T5 | 100 |
| T6 | 85 |
FM: Factory Mutual Research Corporation
The Factory Mutual Approvals Division determines the safety and reliability of equipment, materials, or services utilized in hazardous locations in the United States and elsewhere. Factory Mutual certifies to NEC (National Electrical Code) standards for hazardous locations, NEC Standard 500 (Division classification) and also to the new NEC Standard 505 (Zone classification), which attempts to harmonize American and European classifications. For a product to receive approval, it must meet two criteria:
First, it must perform satisfactorily, reliably, and repeatedly as applicable for a reasonable life expectancy.
Second, it must be produced under high quality control conditions. Factory Mutual also has interlaboratory agreements and can certify to Canadian and European standards.
CSA: Canadian Standards Association
The association includes Canadian consumers, manufacturers, labor, government, and other regulatory agencies among its actively participating influences. These groups work together to generate standard requirements (CSA standards) that demonstrate product quality, enhance market acceptability, and improve quality and safety control procedures in manufacturing and construction for the Canadian marketplace. The standards generated by CSA are the cornerstone for determining a product's eligibility for certification in hazardous locations in Canada. CSA also performs product evaluation, testing, and ongoing inspection to these standards, and also to American and European standards through new interlaboratory agreements.
INERIS / NEMKO / LCIE / BASEEFA
These are some of the recognized European approval agencies that have certified portable radios to Cenelec (European Committee for Electrotechnical Standardization) and/or IEC (International Electrotechnical Commission) standards for hazardous locations. Cenelec attempts to harmonize the electrical standards of its member countries. Generally, IEC standards are used. However, in certain instances where IEC standards are considered too vague, Cenelec defines more precise requirements. The member nations of Cenelec, which include and exceed those of the EEC (European Economic Community), are bound to adhere to these international regulations.
CE Marking
"CE" marking is a declaration from the manufacturer that their product conforms to a specific Directive(s) adopted by the EEA (European Economic Area) and is a requirement for the product to be sold into any of the countries in this 18 member group. CE is an abbreviation for the French phrase Conformité Européene, meaning European Conformance. Unlike hazardous location approvals, the manufacturers are solely responsible for ensuring their product's conformance to these Directives which were developed using IEC and Cenelec standards. The Directives that affect only radio communications equipment are known as the EMC (Electromagnetic Compatibility) 89/336/EEC and LVD (Low Voltage) 73/23/EEC Directives.
These state that the products must meet specific electromagnetic emission and immunity, as well as electrostatic discharge standards. Transmitters that meet EMC standards, as declared by the manufacturer, must be able to withstand interference from the radio frequency spectrum, electrostatic discharge, surges, etc., without the unit's performance being affected. The transmitter must also emit a minimum of the above charges so that it does not affect other nearby electrical devices or systems such as emergency communications or radio and television broadcasts. The Low Voltage Directive addresses basic electrical shock and fire hazard issues. These directives are currently only a requirement for the EEA member nations and are not required for products sold outside this community.
ATEX
ATEX Directive (94/9/EC) is the latest European regulation related to equipment and protective systems intended for use in potentially explosive atmospheres. It came into force on 1st July 2003.
It covers all mechanical and electrical equipment and protection systems used under ground, on the surface, fixed Installations offshore excluding maritime usage.
Countries covered by the directive are all the European Union (EU) countries plus the European Free Trade Area (EFTA) countries: Belgium, Denmark, Germany, Greece, Spain, France, Ireland, Italy, Luxembourg, Netherlands, Austria, Portugal, Finland, Sweden, U.K. and European Free Trade Area (EFTA) countries: Liechtenstein, Iceland, Norway, Switzerland.
Any IS-rated communication product must be serviced at at the appropriate manufacturing facilities, in order to maintain its rating. Under no circumstances should it be serviced at the branch level or an outside shop. A requirement of the IS approval process from the Factory Mutual Corporation (approval body) demands that the radios are serviced at an audited plant.
NB: We cannot advise our customers what ratings of radio equipment they would need for their work environment, for reasons of liability.
There are a number of publications which detail combustion thresholds of hazardous mixtures and the customer should research this themselves.
Information: Courtesy of OSHA, Flow-Tech Inc., Tait Electronics Ltd
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