Valve Selection for Hazardous Environment The explosion-proof performance of the 51-SY (intrinsically safe explosion-proof system) is ExiaIIBT4 (See the reference “Explosionproof Structure Symbol (ExiaIIBT4)”). Selection of a valve for a dangerous place should be done in accordance with “Recommended Practices for Explosion-Protected Electrical Installations in General Industries” issued by Technology Institution of Industrial Safety. This valve should be used in a class-1 or class-2 environment by combining with a barrier (placed in non-hazardous location). Note that this valve can not be used in a class-0 environment. Classification of hazardous environment  Class-0 environment ・・・・・・・・・・ Not available A place where an explosive atmosphere is constantly generated or can be generated. Also, a place where atmosphere is above the lower limit of explosion constantly or for a long time of period is also regarded as the class-0 environment for safety season. (Places often falling into the class-0 environment) a) A container of flammable liquid or space above the liquid level in the container. b) Around the liquid level of flammable liquid in an open container or similar place.  Class-1 environment ・・・・・・・・・・ Available A place where an explosive atmosphere can be generated periodically or occasionally. Also, a place which can have a dangerous concentration of explosive gas due to repair, maintenance, or leakage. (Places often falling into the class-1 environment) a) Around an opening which releases explosive gas due to removal of a product during normal operation, opening/closing of a lid, or operation of a safety valve. b) Around the opening of a container such as a tanker and drum which is filled with flammable liquid. c) Around an opening which releases explosive gas due to occasional operation of a relief valve. d) Around the opening of a gas-vent on a tank etc. e) Around an opening which releases explosive gas during inspection or repair work. f) A room or a place which can have explosive gas due to insufficient ventilation. g) The part which is above the roof of a floating roof tank but within the shell. h) A place which can have leaked explosive gas and can accumulate the gas such as a pit.  Class-2 environment ・・・・・・・・・・ Available A place where explosive atmosphere can be generated under abnormal condition though an explosive atmosphere cannot be generated under normal condition. 1) A place where flammable gas is constantly operated, but it is enclosed in an air-tight container or facility, and concentration of the gas may be thick when the container or facility gets broken due to an accident or when operation fails. 2) A place that can have a dangerous explosive gas concentration due to the breakage of mechanical ventilation equipment though the equipment is usually reliable. Classification of Hazardous Environment (Places often falling into the class-2 environment) a) A place where dangerous gas or liquid can leak from a container if the container is corroded. b) A place where dangerous gas or liquid can be released or leak out due to incorrect operation of equipment or an abnormal reaction of equipment after exposure to high temperature and high pressure. c) A place where a dangerous atmosphere is generated due to failure of mandatory ventilation equipment and stagnation of explosive gas. d) A place which is indoors around or next to the class-1 environment and rarely has explosive gas with dangerous concentration. Wiring of intrinsically safe explosion-proof circuits should not be routed with the other circuits. Also, it should not have electrostatic induction or electromagnetic induction. Intrinsically Safe Explosion-proof Circuit Wiring Disassembling the pilot valve and barrier can deteriorate the explosion-proof performance, and it may lead to an accident. Therefore, please do not disassemble or modify the pilot valve and barrier. Prohibition of Disassembly and Modification Series 51-SY5000/7000/9000 Specific Product Precautions 5 Be sure to read before handling. Refer to back pages 1 and 2 for Safety Instructions, “Handling Precautions for SMC Products” (M-E03-3) for 3/4/5 Port Solenoid Valves Precautions. Warning Warning Warning Warning Back page 7