Dayu Electronics Ultrasonic Level Meter, Submitted for Inspection to Shanghai Explosion-Proof Institute
Dayu Electronics ultrasonic level meter, submitted for inspection to Shanghai Explosion-Proof Institute, explosion-proof rating: Exdll(T4-T6)
The flame propagation capability of explosive gas mixtures indicates the degree of explosion hazard; the greater the flame propagation capability, the higher the hazard. The flame propagation capability of an explosive mixture can be represented by the limiting experimental safe gap. Additionally, the ease with which explosive gases, liquid vapors, or mists are ignited also indicates the degree of explosion hazard, expressed by the minimum ignition current ratio. Class II flameproof or intrinsically safe electrical equipment is further classified into IIA, IIB, and IIC based on the maximum experimental safe gap or minimum ignition current ratio applicable to the explosive gas mixture.
Group | Representative Gas | Limiting Experimental Safe Gap | Minimum Ignition Current Ratio |
IIC | Acetylene, Hydrogen | Less than 0.5mm | Less than 0.45 |
IIB | Ethylene | 0.5～0.9mm | 0.45～0.8 |
IIA | Propane | Greater than 0.9mm | Greater than 0.8 |
The ignition temperature of an explosive gas mixture is the temperature limit at which it can be ignited.
Electrical equipment is divided into groups T1 to T6 according to the limiting surface temperature, so that the surface temperature of the equipment corresponding to each group does not exceed the allowable value for that temperature group. The relationship between temperature class, equipment surface temperature, and the ignition temperature of flammable gases or vapors is shown in the table:
Temperature Class IEC/EN/GB 3836 | Limiting Surface Temperature T (°C) | Ignition Temperature of Flammable Substances (°C) |
T1 | 450 | T > 450 |
T2 | 300 | T > 300 and ≤ 450 |
T3 | 200 | T > 200 and ≤ 300 |
T4 | 135 | T > 135 and ≤ 200 |
T5 | 100 | T > 100 and ≤ 135 |
T6 | 85 | T > 85 and ≤ 100 |