Division 2 Areas

In Division 2 areas, the NEC allows the wiring methods that follow  

PLTC cable (Power Limited Tray Cable), 

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It is generally agreed that a shelter with a roof having ridge ventilation and with curtain walls not extending lower than 8 feet above the operating platform would be freely ventilated. Because a gas compressor would not be a source of hazard, except under abnormal conditions such as an equipment failure, this type of compressor shelter is usually classified as a Division 2 area. 

It is difficult to maintain pressure in thin metal boxes, had a HAZOP had been conducted, these facts, well known to the operating staff, should have been made known to the designers. It should have been known that that compressed air could have been used instead of nitrogen to prevent diffusion into the cabinet. The control cabinet did not have to be in a Division 2 area. 

Batteries should normally be installed in an unclassified area. However, if installed in Division 2 areas, a suitable disconnect switch must be installed to disconnect the load prior to removing the battery leads and tlius avoid a spark if the battery leads are disconnected under load conditions. Batteries should not be installed in Division 1 areas. 

Electrical equipment can be mounted in various types of enclosures. A weather-tight enclosure normally has a gasket and does not allow air (and the moisture contained in the air) to enter the enclosure. Offshore, such an enclosure, if properly closed, will help protect the enclosed electrical equipment from, corrosion due to salt water spray. These types of enclosures can be used in Division 2 areas provided they do not enclose arcing, sparking or high temperature devices. 

In Division 1 areas, transformers must be installed in approved vaults if they contain a flammable liquid. If they do not contain a flammable liquid, they must either be installed in vaults or be approved explosion-proof. In Division 2 areas, standard transformers are acceptable, but... 

Arcing contacts in Division 2 areas must be installed in explosion-proof enclosures, be immersed in oil, be hermetically sealed, or be non-incendive. High-temperature devices must be installed in explosion-proof enclosures. Fuses must be enclosed in explosion-proof enclosures unless the fuses are preceded by an explosion-proof, hermetically sealed, or oil-immersed switch and the fuses are used for overcurrent protection of instrument circuits not subject to overloading in normal use. 

Standard Open or Totally-Enclosed Fan-Cooled (TEFC) generators and motors are acceptable in Division 2 areas if they do not contain brushes or other arcing contacts or high-temperature devices. Three-phase TEFC motors are acceptable in Division 2 locations, but singlephase motors usually contain arcing devices and are not acceptable... 

In both Division 1 and Division 2 areas pendant fixmres must be suspended by conduit stems and provided with set screws to prevent loosening. Stems over 12 inches in length must be laterally braced within 12 inches of fixtures. 

A box or fitting must be installed at each conductor sphce connection point, receptacle, switch, junction point, or pull point for the connection of conduit system. In Division 1 areas only explosion-proof boxes or fittings are allowed. General purpose gasketed cover type fittings are allowed in Division 2 areas. 

Seals are required where 2 in. or larger conduits enter explosion-proof enclosures containing taps, splices, or terminals in Division 1 areas (but not Division 2 areas). 

The equipment used in this application included two Waters M-45 pumps, a Waters 481 UV detector with microbore cell, an air-actuated Rheodyne 7413 injection valve with a 1-pl injection loop, an air-actuated Valeo four-port sampling valve (A2CI4UW2) with no groove in the injection entry ports, an air-actuated Valeo three-port switching valve (AC3W), and a Digital Equipment LSI-11/23 microcomputer. The LC system was located in a purged cabinet suitable for use in Class I, division 2 areas. The cabinet was in a heated room about 40 feet from the reactor column. The two Valeo valves were mounted next to the reactor column, while the microcomputer was located in the control room. 

Group E dusts may be present in hazardous quantities. Group E dusts include combustible metal dusts, including aluminum, magnesium, and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment. The NEC does not recognize any Division 2 areas for such dusts. 

Note Until 1999 the practice in the USA did not recognise type n or the certification of eqnipment for Zone 2 (Division 2) areas. In these areas good quality, standard industrial equipment may be installed. It is worth noting, however, that the NEC, Reference 2, was revised in 1999 and Article 500 now inclndes the lEC system of zones and the types of protection d , e , m , n , o , p and q in Article 505. Type of protection N is not inclnded. 

Division 2 Areas where flammable vapors or gases are handled in proper containers but where hazardous concentrations are normally prevented by forced ventilation. 

Division Area classification based on fikelihood is presented in Table X/3.2.1-2. 

Mark Graham has worked for 14 years with major international service and oil companies in Egypt, Dubai, Brunei, the Netherlands and the UK, prior to co-founding TRACS International. His areas of expertise include petrophysics and asset evaluation. He is Director of the training division of TRACS International and is also responsible for all TRACS projects in the FSU. 

McBain reports the following microtome data for a phenol solution. A solution of 5 g of phenol in 1000 g of water was skimmed the area skimmed was 310 cm and a 3.2-g sample was obtained. An interferometer measurement showed a difference of 1.2 divisions between the bulk and the scooped-up solution, where one division corresponded to 2.1 X 10 g phenol per gram of water concentration difference. Also, for 0.05, 0.127, and 0.268M solutions of phenol at 20°C, the respective surface tensions were 67.7, 60.1, and 51.6 dyn/cm. Calculate the surface excess Fj from (a) the microtome data, (b) for the same concentration but using the surface tension data, and (c) for a horizontally oriented monolayer of phenol (making a reasonable assumption as to its cross-sectional area). 

This text is intended for use by beginning graduate students and advaneed upper division undergraduate students in all areas of ehemistry. 

CS4JSI/SND. The Canadian Scientific Numeric Database Service (CAN/ SND) is provided by the Canada Institute for Scientific and Technical Information (ClSTl), a division of the National Research Council of Canada. It contains 140,000 ir spectra of 96,000 compounds. Entries consist of peak locations and some intensities. This system is searchable on-line using the SPIR (Search Program for Infrared Spectra) (85). Table 9 summarizes the available databases in the area of spectra. 

Rules for the design of shells of revolution under internal pressure differ from the Division 1 rules, particularly the rules for formed heads when plastic deformation in the knuckle area is the failure criterion. Shells of revolution for external pressure are determined on the same criterion, including safety factors, as in Division 1. Reinforcement for openings uses the same area-replacement method as Division 1 however, in many cases the reinforcement metal must be closer to the opening centerline. 

The filtering surface is divided into a number of sec tions by division strips, radial rods, or some other impervious separator. Material which forms a thin, rather impeiMous cake will not form across the dividers, and thus the actual area is somewhat less than the nominal. Where relatively thick cakes of at least 1.5 cm are formed, the cake tends to form across the dividers due to cross-drainage in both the filter cake and the filter medium. In this case, the effective area is relatively close to the nominal area. 

FIG. 18-132 Sectional view of the Cuno Flo-Klean backwashing edge filter. Fluid pumped through the nozzle loosens solids from the filter surface and clears the filtering area. The pump draws filtered fluid from the filter discharge and returns it to the system through the nozzle. Thus, there is no loss of backwash fluid. (Cuno Division, AMF, Inc.)... 

Recognizing all the factors mentioned, the drip-proof type has been the favored enclosure for service in shelters classified Division 2 or in safe areas because it offers adequate protection at the lowest installed cost (see Figure 7-6). In most applications, air-inlake filters and screens have been provided. In one instance, a modified drip-proof enclosure was installed with provision for future filter installation. 

Chaffee, A.L., Loch, H.J. and Pandolfo, A.G., "Methane Adsorption on High Surface Area Carbons" CSIRO, Division of Fuel Technology, Investigation Report FT/IR 03IR (1989)... 

Enclosures for all equipment and panel boards shall be suitable for outdoor installation in areas designated Hazardous Class 1, Group D, Division 2. 

FIGURE 3.4 Process description. Division of process into such parts that their inputs, outputs, and target leveis can be specified. A subprocess can be source or separate area/room that is to be protected from its environment. 

An appropriate division of the efforts just mentioned is helped by defining two areas of composite material behavior, micromechanics and macromechanics ... 

The European philosophy on area classification varies from that of the United. States and Canada. Specifically, in Europe and most other inter national areas, the Zone concept is utilized. An area in which an expio sive gas-air mixture is continuously present, or present for long perioiK of time, is referred to as Zone 0. The vapor space of a closed, but vented, process vessel or storage tank is an example. An area in which an explosive gas-air mixture is likely to occur in normal operations is designated Zone 1. An area in which an explosive gas-air mixture is less likely to occur, and if it does occur will exist only for a short time, is designated Zone 2. Zone 0 and Zone 1 correspond to Division 1 in the U.S. and Canada System. Zone 2 is equivalent to Division 2. 

To promote uniformity in area classifications for oil and gas drilling and producing facilities, the American Petroleum Institute developed RP 500, Recommended Practice for Classification of Locations for Electri cal Installations at Petroleum Facilities Classified as Class 1, Division 1. and Division 2. Figures 17-4 to 17-14 show some common recommended classifications surrounding common production facility equipment as given in RP 500. API RP 500 also provides valuable tutorial information on the philosophies of area classification and the reader is encouraged to become familiar with this publication. 

Hermetically sealed devices are devices sealed to prevent flammable gases from reaching enclosed sources of ignition. These devices are suitable for use in Division 2 and unclassified areas. 

A nonincendive device is one which will not release sufficient energy under normal operating conditions to ignite a specific substance. Under abnormal conditions, such as a malfunction of the device, it may release enough energy to cause ignition. Because of this, such devices are suitable for use only in Division 2 and unclassified areas. 

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