1.1 Division of explosive gas environment hazardous area
Zone 0: continuous or long-term emergence of explosive gas mixtures of the environment.
1 zone: the environment in which explosive gas mixtures may occur during normal operation.
2 zone: in normal operation is unlikely to be explosive gas mixtures in the environment or even if there is only
short-term presence of explosive gas mixtures in the environment.
0 zone generally exists only in closed containers, storage tanks and other internal gas space, in the actual design process 1 zone
also rarely exist, most cases belong to the 2 zone.
1.2, explosion-proof electrical equipment is divided into two categories:
Ⅰ class coal mine electrical equipment
Ⅱ class in addition to the use of electrical equipment in places other than mines
1.3, Ⅱ class electrical equipment, according to its applicability to the maximum test of explosive gas mixtures, safety clearance or the minimum ignition current than that, is divided into Ⅱ A, Ⅱ B, Ⅱ C three categories; and according to the maximum surface temperature is divided into T1 ~ T6. Surface temperature is divided into six groups T1 ~ T6.
1.4, explosive gas mixtures according to the ignition temperature grouping
2. Terminology
2.1, explosion-proof electrical equipment
with the ability to withstand the explosion of the internal pressure of explosive gas mixtures, and to prevent the internal explosion to the shell of the electrical equipment surrounding the spread of the explosive mixture of electrical equipment shells, and its logo is "d".
2.2, safety-enhancing electrical equipment
In normal operating conditions will not produce arcs, sparks or high temperatures that may ignite explosive mixtures, the structure of the measures taken to improve the margin of safety to avoid arcs, sparks or high humidity under normal and recognized overload conditions of the electrical equipment, which is marked as "e ".
3. explosion-proof principle
Electrical equipment ignition of combustible gas mixtures have two reasons: one is the electrical equipment generated sparks, arcs, the other is the electrical equipment surface (i.e., in contact with combustible gas mixtures on the surface) heat. For equipment in normal operation can produce arcs, sparks in the components in the explosion-proof enclosure, or to take the pouring type, sand-filled, oil-filled or positive-pressure type and other explosion-proof type can achieve the purpose of explosion-proof. For increased safety electrical equipment is in normal operation will not produce arcs, sparks and dangerous high-temperature equipment, if the structure and then take some protective measures, try to make the equipment in normal operation or recognized overload conditions will not occur arcs, sparks and overheating phenomenon, you can further improve the safety and reliability of the equipment. Therefore, this equipment in normal operation there is no ignition source, but can be used in explosion-hazardous environments.
4. Examples of explosion-proof signs
4.1, such as electrical equipment for the Ⅱ B explosion-proof T3 group, marked as Exd Ⅱ BT3.
4.2, such as electrical equipment for the Ⅱ type of increased safety, the temperature group for the T2 group, marked as Exe Ⅱ T2.
4.3, such as electrical equipment, the use of more than one type of composite, then the first mark the body Explosion-proof type, and then marked out other explosion-proof type, such as the main body of the increased safety internal Ⅱ C explosion-protected parts, temperature group T4, marked as Exed Ⅱ CT4.
4.4, such as electrical equipment for the dust explosion-proof dust-proof type T11 group. Marked as: DIPDPT11