Hazardous,Area,Guidelines,for, technology Hazardous Area Guidelines for Compliant SCADA Systems

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Normal 0 false false false EN-CA X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-priority:99;mso-style-qformat:yes;mso-style-parent:"";mso-padding-alt:0cm 5.4pt 0cm 5.4pt;mso-para-margin-top:0cm;mso-para-margin-right:0cm;mso-para-margin-bottom:10.0pt;mso-para-margin-left:0cm;line-height:115%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:"Calibri","sans-serif";mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-fareast-language:EN-US;}The suitability of equipment for specific hazardous areas in the NorthAmerican regulated market is required to be tested by a NRTL (NationallyRecognized Testing Laboratory). This is a testing facility, recognized by OSHA(Occupational Safety & Health Administration), as primarily private sectororganizations that provide product safety testing and certification services tomanufacturers. The testing and certification are done, for purposes of the program, toU.S. consensus-based product safety test standards. These test standards arenot developed or issued by OSHA, but are issued by U.S. standardsorganizations, such as the American National Standards Institute (ANSI). Somewell known organizations currently recognized by OSHA as NRTL’s include (butare not limited to): CanadianStandards Association (CSA); FM Approvals LLC  (FM); and Underwriters Labs Inc       (UL). Refer to Article 500 of the National Electrical Code, publication NFPA 70, or Section 18 of the CanadianElectrical Code, publication C22.1 for complete definitions of hazardous areas.  For our purposes, a brief recap follows: Hazardous Location (classified) is a North Americanterm for locations where the potential for fire or explosionexists because of gases, dust, or easily ignitable fibers or filings in theatmosphere.Such an area is categorized according to the nature of the risk and therelative risk level. To define thelevel of safety required for equipment installed in these locations, Classes, Divisions, and Groupsseparate the different hazardous areas: Ø  Classes  define the general form of the flammablematerials in the atmosphere. Ø  Divisions  define the probability of the presence offlammable materials. Ø  Groups  classify the exact flammable nature of thematerial. A Class I Hazardous Location is one in which material may be presentin the air in sufficient quantities to be explosive or ignitable. Some typicalClass 1 locations are:Ø  utility gasplants and operations involving storage and handling of liquefied petroleum gasor natural gasØ  petroleumrefineriesØ  gasolinestorage and dispensing areas When the hazard would be expected to be present in everyday production operations or during frequent repairand maintenance activity, this is called the normal condition. When the hazardous material is expected to be confined within closedcontainers or closed systems and will bepresent only through accidental rupture, breakage or unusual faulty operation, the situation could be calledabnormal. The Code writers designate these two kinds of conditions very simply: normalcondition is deemed  Division 1, and abnormalconditionis known as Division 2. Thus:Ø Class I, Division 1 - Where ignitableconcentrations of flammable gases, vapors or liquids are present within theatmosphere under normal (day to day) operating conditions.Ø Class I, Division 2 - Where ignitableconcentrations of flammable gases, vapors, or liquids are present within theatmosphere under abnormal (system failure) operating conditions.Groups  A,B,C, & D designate the various types offlammability, and for the purposes of most SCADA applications, are quitesecondary to the Class/Division rating. With respect to SCADA systems, radio modems require certificationratings to operate in a hazardous area.  Typically,commercially available gain antennas and virtually all surge suppressors arenot rated.  Due to increased demand forintrinsically safe wireless equipment, however, a growing number of unity gain omni-directional models certifiedfor use in Class I Div 1 areas are more readily available. Field services personnel seeking to meet the compliance requirementsusing (non-rated) directional antennas may consider the following:·        connect the cable and antenna in place on themast before it is deployed in the restricted area, andinstall the antenna at a height that is deemed to be out of the Class I Division 2 zone: typically this zone isunderstood to extend 25 feet outside the adjacent Division 1zone.  As height is one of the most important considerations with respect tooptimizing the operating characteristics of an antenna, this strategy works tothe benefit of the site anyway. GoodSCADAautomation can become GREAT using optimum antenna technology incorporated intothe design from the start. Visit us to learn more and see what great antennaoptions Wavelink Antenna Systems offers. Gary Tootle advises and supportswireless communications professionals throughout USA and Canada  http://www.wavelinkantenna.com/contact.php