Shenhai a prova di esplosione
The explosion-proof marking in explosion-proof lighting fixtures is a label that describes the explosion-proof grade, temperature group, type, and applicable areas of the lighting fixture.
Explanation of Explosion-proof Marking:
As per GB 3836 standards, the explosion-proof marking of lighting fixtures includes:
Explosion-proof Type + Equipment Category + (Gas Group) + Temperature Group.
1. Explosion-proof Type:
Table 1 Basic Types of Explosion-Proof
| Explosion proof form | Explosion proof form sign | Explosion proof form | Explosion proof form sign |
|---|---|---|---|
| Tipo ignifugo | EX d | Sand filled type | EX q |
| Tipo di sicurezza aumentata | EX e | Encapsulation | EX m |
| Barotropic type | EX p | Tipo N | EX n |
| Tipo a sicurezza intrinseca | EX ia EX i | Special type | EX s |
| Tipo di invasione dell'olio | EX o | Dust explosion-proof type | EX A EX B |
2. Equipment Category:
Electrical equipment for esplosivo gas atmospheres is divided into:
Class I: For use in coal mines;
Class II: For use in explosive gas atmospheres other than coal mines.
Class II explosion-proof “d” and intrinsic safety “i” electrical equipment are further divided into IIA, IIB, and IIC classes.
Electrical equipment for polvere combustibile environments is divided into:
Type A dust-tight equipment; Type B dust-tight equipment;
Type A dust-proof equipment; Type B dust-proof equipment.
3. Explanation of Explosion-proof Marking:
The ability of an explosive gas mixture to propagate an explosion indicates its level of explosion hazard. The greater the ability to propagate an explosion, the higher the danger. This ability can be represented by the maximum experimental safe gap. Additionally, the ease with which explosive gases, vapors, or mists can be acceso also indicates the level of explosion hazard, represented by the minimum igniting current ratio. Class II explosion-proof or intrinsic safety electrical equipment is further classified into IIA, IIB, and IIC based on their applicable maximum experimental safe gap or minimum igniting current ratio.
Table 2 Relationship between the Group of Explosive Gas Mixtures and the Maximum Experimental Safe Gap or Minimum Igniting Current Ratio
| Gruppo gas | Maximum test safety gap MESG (m m) | Rapporto minimo di corrente di accensione MICR |
|---|---|---|
| IIA | MESG≥0,9 | MICR＞0,8 |
| IIB | 0.9＞MESG≥0.5 | 0,8≥MICR≥0,45 |
| IIC | 0,5≥MESG | 0,45＞MICR |
4. Temperature Group:
The ignition temperatura of an explosive gas mixture is the limit temperature at which it can be ignited.
Electrical equipment is classified into T1 to T6 groups based on their highest surface temperature, ensuring that the maximum surface temperature of the equipment does not exceed the permissible value of the corresponding temperature group. The relationship between temperature groups, equipment surface temperature, and the ignition temperature of infiammabile gases or vapors is shown in Table 3.
Table 3 Relationship between Temperature Groups, Equipment Surface Temperature, and Ignition Temperature of Flammable Gases or Vapors
| Livello di temperatura IEC/EN/GB 3836 | La temperatura superficiale più alta dell'apparecchiatura T [℃] | Temperatura di accensione delle sostanze combustibili [℃]. |
|---|---|---|
| T1 | 450 | T＞450 |
| T2 | 300 | 450≥T＞300 |
| T3 | 200 | 300≥T＞200 |
| T4 | 135 | 200≥T＞135 |
| T5 | 100 | 135≥T＞100 |
| T6 | 85 | 100≥T＞8 |
5. Requirements for Setting Markings:
(1) Markings should be prominently placed on the main body of the electrical equipment;
(2) The markings must remain clear and durable under potential chemical corrosion. Markings such as Ex, tipo antideflagrante, category, and temperature group can be embossed or debossed on the visible parts of the casing. The material for the marking plate should be chemically resistant, such as bronze, brass, or stainless steel.