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Gree's explosion-proof air conditioning signs are typically composed of five key components, each providing essential information about the equipment's design, purpose, and safety level. Understanding these markings is crucial for proper installation and use in hazardous environments.
1. **Explosion-Proof Sign (EX)** – This prefix indicates that the equipment is designed to be explosion-proof and suitable for use in potentially explosive atmospheres.
2. **Explosion-Proof Structure** – This part specifies the type of protection used. Common types include:
- **d**: Flameproof — the equipment is enclosed in a housing that can withstand an internal explosion.
- **i**: Inherently safe — limits energy to prevent ignition.
- **p**: Positive pressure — maintains a safe internal pressure to prevent flammable gases from entering.
- **e**: Increased safety — prevents sparks or excessive heat under normal operation.
3. **Equipment Category** – Indicates the environment where the device is intended for use:
- **I**: For use in coal mines.
- **II**: For use in non-coal mine environments, such as factories or chemical plants.
4. **Explosion-Proof Level** – Divides the equipment into three levels: A, B, and C, with C being the highest level of protection.
5. **Temperature Group** – Indicates the maximum surface temperature the equipment can reach, which must not exceed the ignition temperature of the surrounding flammable substances. Temperature groups range from T1 to T6, with T6 being the lowest allowable temperature.
For example, the marking **EXdIIBT4** means:
- **EX** – Explosion-proof.
- **d** – Flameproof structure.
- **II** – Factory use.
- **B** – Explosion-proof level.
- **T4** – Maximum surface temperature ≤ 135°C.
According to the GB3836 standard, the general format of an explosion-proof sign is:
**Explosion-proof type + Equipment category + (Gas group) + Temperature group**
There are various types of explosion-proof air conditioners, including flameproof (Exd), increased safety (Exe), intrinsic safety (Exi), positive pressure (Exp), dust explosion-proof (DIP), and others. Each type has specific applications and safety requirements.
Electrical equipment for explosive gas atmospheres is divided into two main categories:
- **Class I**: Used in coal mines.
- **Class II**: Used in other industrial settings.
Within Class II, devices like flameproof (d) and intrinsic safety (i) are further categorized into IIA, IIB, and IIC based on their ability to handle different types of explosive gases.
The temperature group classification ensures that the equipment's maximum surface temperature does not exceed the ignition temperature of the surrounding gases. For instance, T4-rated equipment is safe for use in environments where the ignition temperature is above 135°C.
Additionally, the explosive capacity of gas mixtures is determined by factors such as the maximum test safety clearance (MESC) and minimum ignition current ratio (MICR). These parameters help classify gases into groups like IIA, IIB, and IIC, guiding the selection of appropriate explosion-proof equipment.
Understanding these markings and classifications helps ensure the safe and effective use of Gree’s explosion-proof air conditioning systems in hazardous areas.