Selecting a Safe Tank Gauging Product Understanding Hazardous Area Definitions for Equipment Approvals
Hazardous Area Approvals
A Worldwide Requirement There are many environmental considerations within a location that define a specific type of approval that is needed. The ATEX Directive, which is based on the International Electrotechnical Commission (IEC) standard, defines requirements within the European Union (EU). In the U.S., hazardous area requirements are defined by the National Electric Code, as set forth by the National Fire Protection Association (NFPA). Other countries may use IEC standards or have their own code of standards, such as the CEC in Canada or Russian GOST codes. Hazardous Areas are locations where the potential for fire or explosion exists because of liquids, gases, dust and materials in the atmosphere that could be easily ignited. In North America, hazardous areas are typically separated by classes, divisions and groups to define the level of safety required for equipment installed in these locations. Classes define the general form of the flammable materials in the atmosphere. Divisions define the probability of the presence of flammable materials. Groups classify the exact flammable nature of the material. The more recent NEC Standard 505 attempts to harmonize American and international classifications by using zone classifications. In Europe and countries outside of North America, zones are used to define the probability of the presence of flammable materials. Protection Types denote the safety method used for the device. Groups classify the exact flammable nature of the material, but these groups are separated differently than North American Groups. Lastly, both systems use temperature codes to identify the maximum surface temperature of the device, which ensures the specific gas or vapor encountered in the application will not ignite. Independent test laboratories perform testing and inspection before approving equipment. The Varec 6000 Servo Tank Gauge is approved by multiple laboratories to different standards required worldwide, such as explosion proof/flame proof, as well as being intrinsically safe. Ensure the equipment you select carries clear identification of the pertinent approvals standard.
Hazardous Area Approvals
Flammable Materials and Ignition Sources The application of hazardous area classification and appropriate standards is the responsibility of the end user. For detailed information, see specific standards published by the relevant organizations, for example, the American Petroleum Institute (API RP 500) provides a recommended practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I Division I and Division 2. Zones and Divisions NEC 500 hazardous locations are established into two divisions (1 & 2) based upon the presence of flammable materials under either normal or abnormal conditions, maintenance, repairs or leakage. For countries that utilize IEC or ATEX standards, three Zones (0, 1 & 2) define how often the hazard is present. The aim of NEC, ATEX and IEC standards is to achieve safety by identifying areas where ignition sources should be eliminated or ensuring that the ignition source is noneffective. ATEX and IEC separate NEC s Division 1 into two distinct zones (0 & 1). Zone 0 defines locations that are most hazardous because they continuously remain hazardous under normal conditions. Therefore, ATEX and IEC restrict the method of protection in Zone 0, while permitting a more relaxed method of protection in Zone 1 locations. Zone 0 provides a marked difference between NEC and EU/ IEC standards. Zone 1 locations can be treated as roughly equivalent to Division 1 locations and Zone 2 locations roughly equivalent to Division 2 locations. For most situations, equipment certified for use in a Zone 0 can also be installed in a Zone 1 or 2. Classes and Groups NEC 500 uses Classes (I, II, III) and Groups (A-G) to identify the specific hazard. Classes are used to represent the type of material (gases, dusts, or fibres). Groups are used to represent how ignitable a gas or gas mixture is, with A being the most ignitable and G the least ignitable. The IEC and ATEX Zone systems identify the hazard by two main groups. Group I gases are firedamp methane found in mining/underground locations and Group II are all other explosive gases found in surface industries, such as a terminal or refinery. Group II is divided into three subgroups (A, B & C) arranged in order of hazard due to threat of ignition with A being the most difficult to ignite and C the easiest to ignite. NEC 505 NEC Standard 505 (Zone classification) uses three parallel Zones (0, 1 & 2) to define location, while a single class (1) with four sub groups (A-D) are more closely aligned with EU/IEC Groups IIA, IIB and IIC. Safety standards apply to all electronic equipment and also some mechanical equipment. The Varec 2500 Automatic Tank Gauge, which is mechanically operated, but can also be connected to tank gauge transmitters is ATEX approved for use in hazardous areas. Flammable Material is Present... Continuously Intermittently Abnormally IEC & EU Zone 0 Zone 1 Zone 2 NEC 500 Division 1 Division 2 NEC 505 Zone 0 Zone 1 Zone 2 Typical Gas NEC 505, EU & IEC NEC 500 Acetylene Group IIC Class I / Group A Hydrogen Group IIB + Hydrogen Class I / Group B Ethylene Group IIB Class I / Group C Propane Group IIA Class I / Group D
Hazardous Area Approvals
Types of Protection Depending on the type of protection required for a hazardous area, a device should be selected that offers the corresponding electrical or mechanical design feature that is approved for safe operation. For applications normally encountered by Varec in tank farms, terminals and refineries - intrinsic safety, explosion proof/flame proof are the most common, but non-incendive, encapsulation, purging, oil immersion, powder filling or increased safety may also be a requirement depending on the application. Intrinsic Safety Intrinsic safety is one method of protection for devices that operate in areas with flammable gases, vapors and liquids, such as where fuels are stored and manufactured. An intrinsically safe (i.s.) specification or approval rating means that the device is incapable of releasing sufficient electrical or thermal energy to cause ignition of the most easily ignited concentration of gas present. This type of protection is referred to by IEC as Ex i., by NEC (500) as IS and NEC (505) as AEx i. Explosion Proof and Flame Proof Both Explosion Proof and Flame Proof are used to define the ability of a device enclosure to withstand an explosion and restrict the propagation of the explosion. The certification takes into account the enclosure s ability to restrict the flame path, the ignition energies of the gas, the volume of the enclosure and the normal operating temperature. When all factors are considered, if a gas or vapor ignited within the device, the explosion would need to be contained internally. The IEC Zone system does not allow this flameproof methodology in Zone 0. This type of protection is referred to as Ex d by IEC, XP by NEC 500 and AEx d by NEC 505. Explosion/Flame proof and intrinsic safety concepts can be combined for a single device. The Varec 4590 Tank Side Monitor (TSM) is approved as a Flame proof device that is also intrinsically safe. The 4590 TSM also acts as an intrinsically safe power supply for connected devices, such as radar tank gauges, temperature and pressure sensors. Protection Type NEC 505, EU & IEC IEC Standards NEC 500 Intrinsic Safety Ex i EN 60079-11 (IS) Non-incendive - (NI) Non Sparking Ex na / AEx na EN 60079-15 Explosion Proof - (XP) Flame Proof Ex d / AEx d EN 60079-1
Hazardous Area Approvals
Ambient Environmental Considerations In addition to approvals requirements, consider the ambient atmosphere of the application to ensure that the equipment selected will perform in the environment for which it is intended. Many environments are arduous and may involve the equipment being subject to extreme high or low temperatures, demanding weather conditions, immersion in water or chemical/corrosive attack. Ingress Protection (NEMA) Ingress Protection (IP) specified by IEC provide rates for the environmental (physical) protection an enclosure provides to its internal components from solids, liquids, gases and physical impacts. The American version of IP rating is known as NEMA, but because the tests and evaluations for characteristics are not identical, the IEC classification cannot be exactly equated with NEMA Enclosure Type Numbers. Approximate NEMA Rating Equivalent to IP NEMA rating IP Equivalent 1 10 2 11 3 54 Temperature Ratings and Codes A mixture of hazardous gases and air may ignite when coming in contact with a hot surface. The condition for ignition depends on several factors, such as surface area, temperature and concentration of gas. If the equipment s T rating signifies the temperature generated by the equipment is greater than the ignition temperature of the gas present, the equipment will ignite the surrounding atmosphere and cause an explosion. The T ratings of the EU, IEC and NEC are, in all practicality, the same. The device your application demands may not be approved for use in a hazardous area. In these cases, it may be possible to install your device in an optional enclosure or case that is approved and provides the required protection. The Varec 8130 Remote Terminal Unit is normally installed in non-hazardous areas, such as control rooms, but it is also approved for use in Class 1, Division 2 areas when installed in an optional NEMA 4 enclosure. 3R 14 3S 54 4 & 4X 55 5 52 6 & 6P 67 12 & 12K 52 13 54 Ingress Protection Codes (IPxy) Character x=solids y=liquids 0 None No Protection 1 Objects > 50 mm Vertical (90 ) Dripped Water 2 Objects > 12 mm Dripped Water (75 to 90 ) 3 Objects > 2.5 mm Sprayed Water (30º to 90º) 4 Objects > 1 mm Splashed Water (0º to 90º) 5 Dust Protected Low Pressure Water Jets 6 Dust-tight High Pressure Water Jets 7 Immersion to 1 m (3 ft) 8 Immersion beyond 1 m (3 ft) Maximum Surface Temperature Temperature Class NEC 505, EU & IEC NEC 500 842 F 450 C T1 T1 572 F 300 C T2 T2 536 F 280 C T2A 500 F 260 C T2B 446 F 230 C T2C 419 F 215 C T2D 392 F 200 C T3 T3 356 F 180 C T3A 329 F 165 C T3B 320 F 160 C T3C 275 F 135 C T4 T4 248 F 120 C T4A 212 F 100 C T5 T5 185 F 85 C T6 T6
Measurement, Control and Automation Varec, Inc., deliver measurement, control and automation solutions and professional services for most major oil companies, defense organizations and airlines worldwide. Varec s FuelsManager software applications and hardware products provide local level management and enterprise visibility of liquid petroleum assets at bulk storage facilities, marketing terminals, refineries, petrochemical plants and military fuel facilities. Oil & Gas Since its founding in 1928, Varec has been a leading innovator in the petroleum and chemical sectors, delivering automated systems and professional services for tank farm, terminal and refinery operators and owners worldwide. Today Varec provides completely integrated measurement, control and automation solutions that are specifically designed to ensure safe storage and distribution, track product visibility and provide accurate accounting for the local facility operator to the corporate enterprise. This includes functionality for: Tank gauging and inventory management Supervisory control and data acquisition (SCADA) Overfill prevention, facility monitoring and release detection Terminal and refinery automation Defense Defense operations need a fieldproven fuels management system for real-time, global inventory visibility and accountability. Varec s commercial off-the-shelf solution provides mission critical functionality that is essential to air, ground and marine fueling applications at the base, tactical command or enterprise levels. This includes functionality for: Transaction and inventory management Supervisory control and data acquisition (SCADA) Automatic tank gauging Dispatch and automated data capture (ADC) Aviation Varec provides aviation application services designed for airports, airlines and service providers. The entire aviation industry can now rely on a single solution for aviation fuels management from the fuel farm to take-off. This includes functionality for: Remote or automated, real-time dispatch operations Online or batch-mode paperless fuel ticketing Integrated fuel farm and supervisory control and data acquisition (SCADA) automation Local fuels reconciliation (ExSTARS compliant) Aircraft Communication Addressing and Reporting System (ACARS) messaging and airlines systems integration Enterprise solutions (FuelsManager Aviation Application Services) Varec, Inc. Locations Corporate Headquarters 5834 Peachtree Corners East Norcross (Atlanta), GA 30092 USA Tel: +1 (770) 447-9202 Toll Free: +1 (866) 698-2732 Fax: +1 (770) 662-8939 Houston 5151 San Felipe Sage Plaza, Suite 1100 Houston, Texas 77056 USA Tel: (281) 498-9202 Fax: (281) 498-0183 Asia Pacific Level 8, 91 William St. Melbourne Victoria 3000 Australia Tel: +61 3 8623 6400 Fax: +61 3 8623 6401 Europe Suite 120, 94 London Road Headington, Oxford Oxfordshire, OX3 9FN United Kingdom Tel: 0800 0322389 Fax: 0800 0322389 2009 Varec, Inc. All Rights Reserved. This document is for information purposes only. Varec, Inc. makes no warranties, express or implied, in this summary. The names of actual companies and products mentioned herein may be the trademarks of their respective owners. Document Code: PRO061GVAE0609