Overview of Explosion-Protected
2.Hazardous area classifications
3.Explosion-protecte construction classifications
Flammable gases and flammable liquid vapors (explosive gases) mix with the air to create an explosive atmosphere. This explosive atmosphere will explode when it comes into contact with an ignition source. Explosion can be prevented by removing one of the following three explosive elements: explosive gas, oxygen, or ignition source. Electrical equipment with explosion protected construction is called explosion-protected electrical equipment. Electrical equipment needs to be explosion-protected if it is to be used in hazardous areas. Of these three elements, Daido manufactures explosion-protected electrical equipment by eliminating the ignition source.
2.Hazardous area classifications
Hazardous areas are divided into three classifications based on degree of risk from the frequency of explosive atmosphere generated, the time, etc.
(Special hazardous areas)
|An area where ignitable concentrations of flammable gases, vapors or liquids are present continuously or for long periods of time under normal operating conditions.|
(Class I hazardous area)
|An area where ignitable concentrations of flammable gases, vapors or liquids are likely to exist under normal operating conditions.|
(Class 2 hazardous area)
|An area where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions.|
※For the determination of hazardous areas, see JIS C 60079-10 (Electrical apparatus for explosive gas atmospheres, Part 10 : Classification of hazardous areas)
3.Explosion-protected construction classifications
Explosion-protected equipment is classified by area with explosive gas and use. Daido explosion-protected refrigeration equipment uses flameproof enclosures for the control circuitry and pressurized enclosures for the refrigerant circuits.
|Flameproof enclosures||A flameproof enclosure is an electrical enclosure (container) that can withstand an internal explosion due to the infiltration of flammable gases without suffering damage, and will not ignite flammable gas vapors outside the equipment through any container joint or opening.|
|Pressurized enclosures||A pressurized enclosure is an electrical equipment (container) with a protective gas with a higher pressure than the external atmosphere, and which has sufficiently diluted the explosive gas vapor concentration in it to below the explosive lower limit, so as to maintain its explosion-protected characteristics.
*Pressurized enclosures need to have internal pressure drop detection equipment installed.
|Increased safety enclosure||An explosion-protected construction applicable to electrical equipment that generates no arcs or sparks during normal operation. This type of equipment has increased safety against excessive heat increases or arc/spark generation, and there are means in place to prevent such generation.|
|Intrinsic safety enclosure||An explosion-protected construction in which electric sparks are not generated in the electric circuits, nor will high temperature areas ignite under specific gases under specified test conditions, in normal operating conditions or specific failure conditions.|