When purchasing explosion-proof electric heaters, the following parameters must be clearly defined, otherwise safety supervision acceptance cannot be passed: Explosion-proof Marking (Ex Marking): Must be clearly labeled, for example: Ex d IIB T4 Gb. Ex: Common explosion-proof mark. d/e/p: Explosion-proof type (flameproof/increased safety/pressurized). IIB/IIC: Gas group (IIC is the highest, suitable for hydrogen and acetylene; IIB is suitable for ethylene; IIA is suitable for propane). Choose higher rather than lower. T1-T6: Temperature class (T6 is the highest safety, surface temperature ≤85℃). Must be lower than the ignition temperature of the on-site medium. Gb/Ga: Equipment protection level (Gb is suitable for Zone 1, Ga is suitable for Zone 0). Medium Characteristics: The name, viscosity, corrosiveness, and whether it contains impurities of the heated liquid/gas (affecting material selection and power density). Power Density (W/cm²): Key indicator! Excessive power density can cause the heating tube surface temperature to exceed the limit, leading to explosion. In still air: <1 W/cm²; in flowing water: <5-10 W/cm²; in flowing oil: <2-3 W/cm². Must be strictly calculated based on flow rate. Material Selection: Ordinary environments: 20# steel, stainless steel 304. Corrosive environments: stainless steel 316L, titanium, Hastelloy, fluoroplastic coating. Control System: Is an explosion-proof control box needed? Is a remote PLC interface needed? Is PID precise temperature control needed? 5. Market Mainstream Brands and Origins China's explosion-proof electrical industry clusters are mainly concentrated in Wenzhou (Yueqing), Zhejiang; Nanyang, Henan; Yancheng, Jiangsu; and Fushun, Liaoning. First Tier (industry benchmarks, first choice for large petrochemical projects): Warom (WAROM): Domestic explosion-proof leader, extremely complete product line, participates in multiple national standard formulations, widely used in major Sinopec and PetroChina projects, reliable quality but higher price. Feice Explosion-Proof (FEICE): Representative enterprise in Yueqing, Zhejiang, with strong technological innovation capability, outstanding performance in the field of intelligent explosion-proof. Nanyang Explosion-Proof (CNE): Old state-owned enterprise background, strong scientific research strength, good at large complex explosion-proof systems. Second Tier (high cost performance, main force in general market): Explosion-proof etc.: Deep accumulation in specific fields (such as pipeline heating, mining heating), good cost performance. International Brands: Eaton (Crouse-Hinds), Emerson (Appleton): World top-level, extremely high prices, mainly used for wholly foreign-owned projects or offshore platforms with strict certification requirements. 6. Safety Use and Maintenance Regulations Strictly prohibit opening the cover while energized: In hazardous areas, the junction box can only be opened for maintenance after power is off and no residual charge is confirmed ("strictly prohibit live work" is an iron rule). First medium, then power: For pipeline or immersion heaters, ensure the medium is flowing or submerged before powering on to prevent dry burning causing surface temperature to instantly exceed the limit and cause explosion. Regularly clean dust: For dusty environments, regularly clean dust on the heater surface to prevent dust accumulation affecting heat dissipation and causing over-temperature. Seal ring inspection: After each maintenance, check and replace aged rubber seal rings to ensure the flameproof surface is intact. Reliable grounding: Must have independent anti-static and anti-leakage grounding measures. Summary Suggestions If you are purchasing explosion-proof electric heaters for chemical plants, gas stations, or coal mines: Verify the area classification: Confirm whether the site is Zone 0, Zone 1, or Zone 2, and select Ga, Gb, or Gc level equipment accordingly. Confirm the gas/dust group: If it is a hydrogen environment, IIC level must be selected; if it is ordinary oil and gas, IIB level is sufficient. Strictly control surface temperature: Based on the medium ignition point, Recommended brands: For ultimate safety and large project acceptance, prefer Warom or Nanyang Explosion-Proof; for general civil explosion-proof or limited budget, choose regular large factories in the Yueqing area (need to verify the explosion-proof certificate).
