Exproof Heaters
ATEX-Approved Electric Duct Heaters for Areas with Explosive Atmosphere Risk
Exproof Heaters are ATEX-compliant electric heating solutions used to safely heat duct air, air handling unit air or process air in industrial facilities where explosive gases or vapours may occur.
Suitable for Zone 1 and Zone 2 hazardous areas, these systems can be engineered for safe air-heating applications with IP66 protection, T3 temperature class, integrated overtemperature protection and temperature-limiting equipment.
ATEX Zone 1 / Zone 2
Suitable for hazardous areas with an explosive atmosphere risk caused by gas or vapour.
1–1000 kW Capacity
Provides low- and high-capacity electric duct heater solutions according to process requirements.
IP66 and T3 Class
Delivers safe industrial air heating with IP66 protection and T3 temperature class.
What Is an Exproof Heater?
Exproof heaters are specialised heating systems designed to perform electric heating safely in industrial areas where an explosive atmosphere may form. Unlike standard electric heaters, their enclosure, terminal box, temperature limiters, cable entries and electrical connections are assessed according to ATEX requirements.
Rectangular electric duct-type exproof heaters can be used in duct systems, central air handling units, process ventilation lines, offshore facilities, chemical plants, the oil industry and marine applications.
How Exproof Heaters Work
Air Inlet
Process air or fresh air is directed through the duct to the heater body.
Electric Heating
Stainless-steel or special-alloy tubular heating elements heat the airflow in a controlled manner.
Temperature Limiting
Overtemperature protection and a temperature limiter keep surface and outlet temperatures within a safe range.
Safe Outlet
The heated air is transferred to the process through the duct or air handling unit line.
Key Technical Features
Exproof Heater Technical Data Table
| Technical Feature | Value / Description |
|---|---|
| Product type | Exproof / ATEX electric rectangular duct heater |
| Application area | Duct systems, air handling units and industrial process air-heating applications |
| Hazardous-area suitability | Zone 1 and Zone 2 areas with gas / vapour risk |
| Equipment category | 2G |
| ATEX marking | II 2 G Ex db eb mb IIC T3 Gb |
| Temperature class | T3, maximum surface temperature of 200°C |
| Outlet air temperature | Maximum 40°C |
| Capacity range | 1 kW – 1000 kW |
| Minimum air velocity | 2.5 m/s |
| Ambient temperature | -50°C / +40°C |
| Protection rating | IP66 |
| Installation orientation | Horizontal or vertical installation |
| Enclosure material | EN 1.4301 stainless steel or EN 1.4404 acid-resistant stainless steel |
| Heating element material | EN 1.4301, EN 1.4404, Incoloy 800 or Incoloy 825 |
| Voltage option | Adaptable up to 690 VAC, 3-phase, according to customer requirements |
Model and Application Types
| Model Type | Installation / Application Method | Application Note |
|---|---|---|
| VFL2-Ex type | Flanged duct connection | Suitable for applications connected to the duct system through a flange. The heating-element magazine has a removable construction. |
| VTL2-Ex type | Plug-in installation inside the duct | Preferred for compact applications where the heater is installed within the duct cross-section. |
| VRA2-Ex type | Air handling unit / air preparation unit installation | Used for ATEX-required air handling unit or process air preparation unit applications. |
ATEX Classification Information
| Marking / Class | Meaning | Meaning for the Exproof Heater |
|---|---|---|
| II | Equipment group for hazardous areas other than mines | Industrial facilities, process areas, offshore and marine applications |
| 2G | Equipment category for Zone 1 and Zone 2 gas atmospheres | Explosive atmospheres caused by gas or vapour |
| Ex db | Flameproof enclosure | Assessed for protective circuits and temperature safety |
| Ex eb | Increased safety | Terminal box and connection safety |
| Ex mb | Encapsulation protection type | Temperature limiters and protective equipment |
| IIC | The most demanding gas group, including hydrogen and acetylene | Suitability assessment for IIA, IIB and IIC gas groups |
| T3 | Maximum surface temperature of 200°C | Can be used in T1, T2 and T3 applications; lower temperature classes require separate assessment |
| Gb | Equipment protection level | Protection level suitable for Zone 1 / Zone 2 gas-atmosphere use |
Design and Material Features
Project Selection Criteria
| Selection Parameter | Point to Consider |
|---|---|
| Airflow rate | The air velocity passing through the heater cross-section must meet the minimum value of 2.5 m/s. |
| Heating capacity | Calculated according to airflow rate and temperature rise using the P = Q × 0.36 × Δt approach. |
| Duct dimensions | Width and height dimensions are assessed between a minimum of 200 mm and a maximum of 3000 mm. |
| Installation orientation | Horizontal or vertical installation is possible; the airflow direction must follow the arrow marked on the unit. |
| Fan interlock | The heater must be interlocked with the fan or airflow; power must be disconnected if airflow stops. |
| Pressure loss | Must be calculated according to air velocity and the number of heating-element rows. |
Application Areas
Application Note
When selecting an exproof heater, the site ATEX zone classification, gas group, temperature class, airflow rate, duct dimensions, required temperature rise, fan interlock system, control panel, cable entries and local ATEX electrical-installation requirements must be assessed together.
Get Technical Support for Exproof Heater Selection
Exproof heater selection must be based on the ATEX zone classification, gas group, temperature class, airflow rate, required temperature rise, duct dimensions, control system and site installation conditions.
You can request a project-specific technical evaluation for ATEX-compliant electric duct heaters, air handling unit heaters and process air-heating applications.
