An explosion-proof pressure transmitter refers to an instrument whose electrical components (such as circuits, wiring terminals, and housing) have been specially designed, manufactured, and certified to operate safely in explosive gas, vapor, or dust environments without becoming an ignition source.

Main explosion-proof types (protection types)

1. Flameproof type
   • Marking: Ex d
   • Features: Robust, reliable, and the cover can be opened while powered during maintenance (only in safe areas or after confirming power-off). It is one of the most commonly used explosion-proof types for transmitters and is often used in Zone 1 and Zone 2.
2. Intrinsically safe type
   • Marking: Ex ia or Ex ib
   • Features: Light weight, small size, and can be maintained while powered in hazardous areas. However, it must be used in conjunction with associated equipment (safety barriers), and the overall system cost needs to be considered.
3. Increased safety type
   • Marking: Ex e
   • Features: Cannot be used alone for active switch components. Commonly used in junction boxes, lamps, etc. In transmitters, it is often combined with flameproof type (e.g., the junction box is increased safety type).
4. Moulded case type
   • Marking: Ex m
   • Features: Small size, but once damaged, it cannot be repaired. Commonly used in small sensors or transmitter modules.
5. Pressurized type
   • Marking: Ex p
   • Features: Complex system, requires a gas source and monitoring system, usually used in large analysis cabinets or control panels, and less commonly used for individual transmitters.

For pressure transmitters, the most common combinations are: Flameproof type (Ex d) or Intrinsically safe type (Ex ia/ib).

Example of explosion-proof marking interpretation: A complete explosion-proof marking contains all safety information. For instance: Ex d IIC T6 Gb

• Ex: Explosion-proof symbol.
• d: Explosion-proof type (flameproof type).
• IIC: Gas group (indicating it is suitable for the most explosive gases such as hydrogen and acetylene, covering groups IIA and IIB).
• T6: Temperature group (indicating the maximum surface temperature of the equipment does not exceed 85°C).
• Gb: Equipment protection level (applicable to Zone 1 and Zone 2).

The core differences between explosion-proof and non-explosion-proof transmitters

Explosion-proof pressure transmitters are the "guardian angels" and "legal red lines" for safe production. The selection and application of them are not issues of optimizing technical performance, but rather mandatory safety guarantees under the law.