Presentation on Flameproof Equipments

Flameproof Now What is Flamproof 1.Not liable to catch fire or be damaged by fire 2. Any apparatus designed so that an internal explosion will not ignite external flammable gas. Hazardous Area all classified into Zones & Gas Groups:- Zones:- The zone defines the probability of hazardous material being present In an ignitable concentration in the surrounding atmosphere. Groups:- Classify the exact flammable nature of the material Zone 0 Area in which an explosive gas-air mixture is continuously present or present for long periods. Zone 1 Combustible or conductive dusts are present. Area in which an explosive gas-air mixture is likely to occur for short periods in normal operation. Zone 2 Area in which an explosive gas-air mixture is not likely to occur, and if it occurs it will only exist for a very short time due to an abnormal condition. NEC® 500, HAZARDOUS MATERIALS CLASSIFICATION According to NEC® 500, hazardous materials are classified into three classes of flammable materials:- • Class I : Gases, vapors and liquids • Class II : Combustible dust • Class III: Ignitable fibers or filings CLASS I MATERIALS CLASSIFICATION Class I materials are typical of petrochemical environments. They are further divided into the following groups: • Group A • Group B • Group C • Group D NEC® 505 (ZONE SYSTEM) CLASSIFICATION Comparison Between Division and Class Grouping Typical Gas Division System Zone System NEC® Article 500 NEC® Article 505 Acetylene Group A Group IIC Hydrogen Group B Group IIC Ethylene Group C Group IIB Propane Group D Group IIA Protection Types Different protection techniques are used to address the hazardous zones Zone Ex d Flameproof (Explosion proof) Enclosure 1, 2 Ex e Increased Safety 1, 2 Ex ia Intrinsically Safe 0, 1, 2 Ex ib Intrinsically Safe 1, 2 Ex o Oil Immersion 2 Ex p Pressurized Apparatus (Purged Apparatus) 1, 2 Ex q Powder Filling (Sand Filling) 2 Ex m Encapsulation 1, 2 Ex n or Ex N Non incentive or/and normally no sparking circuits 2 Intrinsically Safety The electrical energy available in circuits and equipment, is limited to a level to low to ignite the most easily ignitable mixtures in a hazardous area. Intrinsically safe barriers, as Zener, are installed in the circuit to limit current and voltage in the hazardous areas to avoid sparks or hot spots under fault conditions. Encapsulation Equipment components of the equipment are usually encased in a resin type material Pressurized Apparatus (Purged Apparatus) Equipment is pressurized with a positive pressure; gas cannot get in for air coming out or equipment is purged with a diluting gas such as air. If air is used, it is ducted in from outside the hazardous area. INGRESS PROTECTION (IP) RATING IP Rating is assigned to enclosures for degree of protection provided by them The IP rating normally has two numbers:- 1. Protection from solid objects or materials 2. Protection from liquids (water) IP First number – Protection Against solid objects 0 No special protection 1 Protected against solid objects up to 50 mm, e.g. accidental touch by persons hands. 2 Protected against solid objects up to 12 mm, e.g. persons fingers. 3 Protected against solid objects over 2.5 mm (tools and wires). 4 Protected against solid objects over 1 mm (tools, wires, and small wires). 5 Protected against dust limited ingress (no harmful deposit). 6 Totally protected against dust. IP Second number – Protection Against liquids 0 No protection. 1 Protection against vertically falling drops of water e.g. condensation. 2 Protection against direct sprays of water up to 15o from the vertical. 3 Protected against direct sprays of water up to 60o from the vertical. 4 Protection against water sprayed from all directions – limited ingress permitted. 5 Protected against low pressure jets of water from all directions –limited ingress. 6 Protected against temporary flooding of water, e.g. for use on ship decks- limited ingress permitted. 7 Protected against the effect of immersion between 15 cm and 1 m. 8 Protects against long periods of immersion under pressure. Temperature Codes A mixture of air and hazardous gases may ignite by coming in contact with a hot surface. An ignition depends on surface area, temperature and the concentration of the gas. Certified equipment are tested for maximum temperature ratings by approval agencies. Equipment for Group II receives a temperature code indicating the maximum surface temperature. Temperature Code oF oC T1 842 450 T2 572 300 T3 392 200 T4 275 135 T5 212 100 T6 185 85 GROUPS Electrical equipment are divided into two groups where Group I covers equipment used in mines and Group II covers all other applications. Group II is subdivided into three subgroups:- Group I For application in below ground installations (mines)where methane (firedamp) and coal dust may be present. Group IIA Industrial Methane, Propane, Petroland the majority of industrial . Group IIB Ethylene, coke oven gas and other industrial gases . Group IIC Hydrogen, acetylene, carbon disulphide Apparatus marked IIB can also be used for IIA gases. IIC marked equipment can be used for both IIA and IIB. If a piece of equipment has just II and no A, B, or C after then it is suitable for any gas group.