Immersion Heaters | ATEX Zone 1 & Zone 2 Hazardous Area Heaters

View Sub Products

Immersion Heaters - Hazardous Area Zone 1 & Zone 2 (ATEX)

ATEX Immersion Heaters : Zone 1 & Zone 2 (IIA, IIB, IIC) Hazardous Areas

Immersion Heaters

Explosive Atmospheres & Hazardous Area Electrical Heating Products

Thorne & Derrick International are leading stockists and suppliers of IECEx & ATEX certified hazardous area electrical heating equipment to the UK and global oil, gas, petrochem and explosive atmosphere industries – this includes EXHEAT immersion heaters for Zone 1 and Zone 2 hazardous areas.

Immersion heaters for Zone 1 and Zone 2 classified hazardous areas provide flameproof heating for gases, oils, heat transfer fluids and corrosive solutions – this includes Zone 1 / Zone 2 (Gas) or Zone 21 / Zone 22 (Dust) or Class I, Division 1 and Division 2.

The immersion heater range can also be used in other applications including boiler equipment, process heating equipment, hot water storage tanks and heat transfer systems.

Thorne & Derrick are global distributors for the full EXHEAT range of ATEX immersion heaters and can supply products in varying voltages and configurations customised to clients requirement.

Typically manufactured from milled 316 stainless steel with weatherproof protection to IP66, ATEX heaters can also be provided with a choice of built in process temperature sensors.

Immersion heaters are submerged in water, oils, solvents, process solutions, molten materials and gases where the heater element releases all their heat within the fluid which makes them nearly 100% energy-efficient. Immersion heaters are offered in a wide variety of sizes, kilowatt ratings, voltages, terminations, sheath materials and accessories – we can produce custom engineered heaters for a specific application.

Immersion Heating Elements

EXHEAT offers a range of immersion heating element types for a wide variety of applications – Thorne & Derrick will work with you to
determine the most suitable type for client application, material, specification and budget. Contact us to discuss your requirements.

Rod Type Element

Metal sheathed with mineral insulated rod elements are the most versatile and cost effective method of electric heating.

  • Various materials available subject to design parameters and medium; Incoloy 800, 825 or 304, 316L, 321 stainless steel
  • L-shaped element bend formation for vertical orientated tanks
  • 8mm, 10mm, 12.5mm diameter heater elements
  • Electrical supply up to 600V (CSA) and 690V
  • 100% heating efficiency
Immersion Heater Rod Type

Removable Core Element

Removable ceramic core type elements are designed for use in heating large tanks having the advantage that maintenance can be done without the need to drain the tank.

  • Elements can be withdrawn / removed without system drain down
  • Mild steel or 316L stainless steel element sheath
  • Short lead time heaters
  • Single cores available 1Ph or 3Ph
  • 38mm or 45mm diameter heater elements
  • Low watts density (surface temperature across the element)
  • Electrical supply up to 600V (CSA) and 690V
  • 100% heating efficiency
Immersion Heater - Removable Core

Cartridge Type Elements

Cartridge elements are similar in construction to rod elements only both terminations are made at a single end. This allows immersion heating elements to be installed within a removable
element heater construction.

  • Elements can be withdrawn / removed without system drain down
  • 304 and 316L stainless steel heating elements
  • 10mm or 12mm diameter heating elements
  • Electrical supply up to 600V (CSA) and 690V (ATEX / IECEx) 4-W STAR or 3-W STAR with Floating Neutral wiring configuration
  • 100% heating efficiency
Immersion Heater - Cartridge Type


Hazardous Area Electrical Heating Product OverviewExplosive Atmospheres EX

  • Standard Flameproof Immersion & Tank Heaters – delivered from stock overnight
  • Custom Engineered Flameproof Immersion & Tank Heaters – designed and delivered on short manufacturing lead times
  • Heat Output 100W to 150W
  • Fitted with industry flange connections or a threaded boss in variety of materials
  • Immersion heaters for direct immersion into process fluids – rod/hairpin, ceramic core or cartridge-type heating elements

➡ The immersion heaters connections are protected by robust Exd terminal enclosure fitted with process control thermostat and over-temperature protection.

For non-standard applications, Thorne & Derrick are available to assist in specifying and designing the correct hazardous area electrical heating solution – this includes heat tracing systems using trace heating cables to provide frost protection and process temperature maintenance to pipework and mechanical services.

Air Heaters | Immersion Heaters | Line Heaters | Thermostats | ATEX & IECEX Certified Electrical Heaters

ATEX Certified Immersion Heaters ( Zone 1 & Zone 2)

ATEX Certified Immersion Heaters ( Zone 1 & Zone 2)

EXHEAT Heaters

EXHEAT Stockists


EXHEAT Industrial offers fast-track electrical heating and process solutions suited to the diverse requirements of the industrial, non-hazardous and hazardous area industry sectors – providing the most extensive range of engineered electrical heating systems including:

  • Hazardous area air warmers, enclosure heaters and industrial convector and fan heaters
  • Space heaters, radiators, convector and fan-type heaters designed for smaller enclosures/cabinets or larger room/containers
  • Immersion heaters for direct immersion into process fluids – rod/hairpin, ceramic core or cartridge-type heating elements
  • Line heaters providing clean, safe and efficient heating for bulk liquid (corrosive/non-corrosive) flow applications in hazardous areas
  • Weatherproof and flameproof industrial sensors/controls and thermostats integrated with EXHEAT heaters
  • Industrial, baptistery and portable immersion heaters
  • Heating elements (rod, cartridge and core type)
  • Flameproof instrument housing and transmitters
  • ATEX Zone 1 Zone 2 (Gas) & Zone 21 22 (Dust) Explosive Atmospheres
  • Also | ATEX Fans (Portable Ventilation)
Hazardous Area Electrical Heaters | International Certifications

Hazardous Area Electrical Heaters | International Certifications

Air Warmers & Fan Heaters - Hazardous Area Zone 1 & Zone 2 (ATEX)

T&D International : EXHEAT Distributors – Stockists & Suppliers of Hazardous Area Electrical Heating Equipment

Hazardous Area

Zone 1 & Zone 2 Immersion Heaters

EXHEAT Heaters Product Range

EXHEAT FP Flameproof Rod Type Immersion Heaters – ATEXEXHEAT FP-C Flameproof Removable Core Immersion Heaters – ATEXEXHEAT FP-CA Flameproof Removable Cartridge Immersion Heaters – ATEX
EXHEAT FP Flameproof Rod Type Immersion Heaters - ATEX EXHEAT FP-C Flameproof Removable Core Immersion Heaters - ATEX EXHEAT FP-CA Flameproof Removable Cartridge Immersion Heaters - ATEX
EXHEAT HB Removable Core Type Industrial Immersion HeatersEXHEAT HB Rod-Type Industrial Immersion HeatersEXHEAT HRF Heaters – Immersion Heaters
EXHEAT HB Removable Core Type Industrial Immersion Heaters EXHEAT HB Rod-Type Industrial Immersion Heaters EXHEAT HRF Heaters - Immersion Heaters
EXHEAT RFA Flameproof Rod-Type Heaters – ATEXEXHEAT RFA-C Core Flameproof Heaters – ATEXEXHEAT RFA-CA Flameproof Cartridge Heaters – ATEX
EXHEAT RFA Flameproof Rod-Type Heaters - ATEX EXHEAT RFA-C Core Flameproof Heaters - ATEX EXHEAT RFA-CA Flameproof Cartridge Heaters - ATEX


Selecting an Immersion Heater

Most electrical heating requirements can be solved by converting the heat requirement to its equivalent electrical power. Whatever the application the method for determining the power requirement considers the following.

Properties of the Material to be Heated  it is important to know the type and quality of the fluid being heated. For example, if the fluid is water, is it clean or contaminated or potable? Acids cause corrosion and insulating buildup on the heater sheath which can cause overheating and heater failure. If the fluid is thick and viscous oil, it requires a low watt density, whereas light oil could tolerate sheath watt densities to 30 W/sq. in. to 40 W/sq. in. – avoiding coking by considering the oils viscosity, specific heat and thermal conductivity.

Startup and Maximum Operating Temperatures – in essence, this is related to the temperature difference (delta T) between startup and operating conditions.

Maximum Flow Rate of the Material being Heated – this factor determines the wattage required. The minimum flow rate also might be required to help determine the watt density requirements. Too low a flow rate and too high a watt density can lead to excessive coking or excessive sheath temperatures in oil applications.

Cycle Time – the longer the startup time allowed, the lower the kilowatt requirement.

Mass of the Heated Material – this determines kilowatt requirements for startup.

Characteristics of the Containing Vessel – the weight determines the kilowatt requirement for startup. Vessel dimensions and presence of a cover determine heat loss. The vessels material of construction affects heater choice and mounting configuration. Heaters for pressurized vessels can bear the ASME code stamp.

Insulation – insulation thickness and properties affect heat loss from the vessel. Mineral-insulated cable or heat tracing cable compensates for losses from connecting piping.

Temperature Monitoring and Control – sensing and control methods and locations depend on the precision requirements for the process and heater sheath temperatures. For example, a simple freeze protection application might require only a mechanical bulb and capillary-type thermostat. For more precise measurement and control, a thermocouple or RTD might feed a PLC. A high-limit sensor on the sheath prevents overheating and premature failure or can determine if there is excessive contaminant buildup.

Environmental Conditions – ambient temperature and wind conditions can affect heat loss and should be taken into consideration when calculating kilowatt requirements. Hazardous, corrosive and explosive atmosphere environments are important factors.

Sizing the heater

The basic steps in sizing an immersion heater involve calculating the following:

  1. Power required for heating of the fluid and the tank. Use standard heat-transfer equations to calculate the fluid heating requirement
  2. Power required to heat the fluid during the operating cycle
  3. Heat required to melt or vaporize materials during initial heating
  4. Heat required to melt or vaporize materials during operating cycle
  5. Heat losses by standard equations
  6. Total startup power requirements. The results of steps 1 and 3 are added together and an appropriate safety factor is applied
  7. Total operating power requirements. The results of Steps 2, 4 and 5 are added and the safety factor applied
  8. Watt density. Calculate the total wattage divided by the active heater surface area based on the length of heater element immersed in the fluid, the surface area per inch, and the total number of heater element lengths

Immersion Heaters - Hazardous Area Zone 1 Zone 2 - Glycol Boilers KO Dums Tank Heating

  • Tank Heating – core and cartridge element immersion heaters provide hazardous area tank heating with exact control of liquid temperature, virtually 100% energy efficiency and ensuring a reliable and fast heat up time for water, solvents, molasses, syrups and petroleum products.
  • Glycol Reboilers – hazardous area heaters are installed within the reboiler to thermally regenerate glycol – providing a clean, efficient controllable heat source with controlled sheath temperatures so as not to burn the glycol.
  • KO Drums – electric heaters increase temperatures of separated liquids – a vapour-liquid separator may also be referred to as a flare KO drum, flash drum, knock-out drum, knock-out pot, compressor suction drum or compressor inlet drum.
Knock Out Drums - Hazardous Area Heaters Heating

Photo by: Jeff Latture, Barnhart.

This photograph highlights the challenges of servicing the worldwide oil and gas industry –  barge delivery of a knock-out drum fighting through a waterway frozen by the polar vortex. From Saharan deserts to Arctic tundra the combined challenges of temperature extremes, potentially explosive atmospheres and harshest operating environments place significant importance upon the specification of equipment in accordance with international classifications.

Some Typical Electrical Heating Applications

➡ Should you require assistance with a specific process, storage or bulk liquid heating application or selection of the correct electric heater please do not hesitate to contact us – for specialist custom and complex surface heating applications please see our range of silicone heaters.

AirAir HandlingAir HeatingAir ThermostatsAir ConditioningAircraft HangersAmmunitionAnalyser Houses
Anti-Ice StationsAviation Fuel Test AreasBattery RoomsCanopyCatalyst OxidastionFlameproof AreasChemical Injection SystemsChemical Plant Warehouses
Chemical PlantsChemical StoresContainersCrane CabsDairiesDeluge SkidsDimplex HeatersDog Houses
Drilling FloorsDrying Ovens & RoomsDust ExtractorsElectrical SubstationsEquipment CabinsExplosive StoresFire Equipment SkidsFire Shelters
Firework FactoriesFlammable Liquid StoresFPSOFrost ProtectionGas InstallationsGas RegenerationGas StorageGenerator Rooms
Resin Drying RoomsSafe ContainersSalty AtmospheresSewage PlantsShipping ContainersSilo HeatersSite CabinsSkids
Solvent StorageSpace HeatingSpray BoothsSubstations HVSugar RefineriesSurface Mining HeatersTest RigsVentilation


Process Heating

Fuel GasGlycol RegenerationCrude OilHydrocarbon LiquidsSeawaterNitrogen | Air
OxygenProcess GasHeat Transfer LiquidsWaterHot Water CalorifiersHVAC
Natural GasFlammable GasFuel OilHydrocarbonsSteamsSolvents
ATEX EX Hazardous Area Heating - EXHEAT

Offshore Oil & Gas Electrical, HVAC & Process Instrumentation Equipment

Thorne & Derrick | Experts in Equipment for Explosive Atmospheres

Specialist Distributors of Hazardous Area & Explosion Proof Equipment with IECEx & ATEX Certifications to the onshore and offshore oil, gas, petrochemicals and process industries.

Key Product Categories: Control Panels | Plugs & Sockets | Isolators | Enclosures & Junction Boxes | Lighting | Control Stations | Motor Starters | Heat Trace Cables & Systems | Gas Detection & Detectors | Fire Detection & Detectors | Heat Detectors 

Hazardous Area Electrical Equipment

Hazardous Area Certification - INMETRO GOST IECEX ATEX FM Zone 1 Zone 2

EXHEAT Heaters & International Hazardous Area Classifications include IECEx, ATEX, INMETRO, GOST & EAC.