Explosion-proof electric heaters are explosion-proof electrical devices specifically designed for explosive atmospheres. Their core function is to convert electrical energy into heat energy to heat liquid, gas, or solid media, while preventing internal explosive flames from leaking out and causing an external explosion. Their design strictly adheres to the GB3836 series of national standards (such as GB3836.1-2010 "Explosive Atmospheres - Part 1: Equipment - General Requirements" and GB3836.2-2010 "Explosive Atmospheres - Part 2: Equipment Protected by Flameproof Enclosures 'd'"), and are suitable for hazardous locations in petroleum, chemical, coal mining, and gas-fired environments where flammable gases (such as hydrogen, ethylene, and methane) or dust are present.
I. Core Working Principle and Explosion-Proof Mechanism The core of explosion-proof electric heaters is the "explosion-proof enclosure":
Enclosure Structure: Made of high-strength metal materials (such as cast steel and stainless steel), capable of withstanding internal explosion pressure (typically ≥1.5 times the maximum explosion pressure);
Gap Design: The gap between the enclosure and internal electrical components is strictly controlled (e.g., joint surface width, roughness) to ensure that the explosion flame is cooled below the ignition temperature of the external explosive mixture when passing through the gap;
Internal Sealing: Junction boxes, terminal blocks, and other parts use sealing materials (such as epoxy resin and silicone) to prevent external explosive gases from entering the interior.
II. Main Product Types and Application Scenarios Explosion-proof electric heaters can be classified into the following categories according to the heating medium and structural form:
Liquid Heating Type: Used for heating liquids such as oil, water, and chemical raw materials, commonly found in reaction vessels and storage tanks in oil refineries and chemical plants.
Gas Heating Type: Used for heating gases such as air, natural gas, and steam.
III. Key Performance Parameters and Selection Considerations When selecting an explosion-proof electric heater, the following parameters should be given special attention:
* Explosion-proof rating: Select according to the type of explosive mixture in the environment, such as:
* Gas environment: IIA (propane), IIB (ethylene), IIC (hydrogen). The higher the rating (e.g., IIC), the stronger the explosion-proof capability.
For example, in a hydrogen environment, Ex d IIC T6 level (maximum surface temperature ≤ 85℃) should be selected; in an ethylene environment, Ex d IIB T4 level (maximum surface temperature ≤ 135℃) should be selected.
IV. Maintenance and Safety Precautions
* Regular inspections:
* Monthly check insulation resistance (measured with a megohmmeter, ≥ 100MΩ);
* Quarterly check wiring terminals (for looseness or oxidation);
* Annually calibrate the temperature controller (error ≤ ±0.5℃).
* Safe operation:
* The equipment must be properly grounded (grounding resistance ≤ 4Ω);
* Do not operate above the rated temperature or pressure;
* Power must be disconnected before maintenance, and the equipment must be cooled down before proceeding.
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Post time: Dec-10-2025
