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Hazardous Area Heating Zone 1 & Zone 2

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hazardous area heating

Thorne & Derrick Are International Distributors Of Zone 1, Zone 2 Hazardous Area Heating 

There are many gases, mists, vapours and dusts that can form explosive atmospheres when mixed with air. Hazardous area classifications are used to identify and warn of the presence or potential threat of gases in a working area and are specified as Zone 1, Zone 2, Zone 21 and Zone 22.

The classifications and designation of an area as hazardous enables the correct precautions to be taken over sources of ignition in order to prevent fires and explosions. Hazardous area classification should always be carried out as part of a work place risk assessment.

When assessing the level of risk, hazardous and non-hazardous area classification should be carried out systematically and should be used to determine if hazardous areas exist and to then assign zones to those areas.

The risks from not using the appropriate or properly specified equipment in the wrong areas or zones can be catastrophic with explosions occurring and endangering personnel and plant.

The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) provide a specific legal requirement to carry out a hazardous area study, and document the conclusions, in the form of zones.

Hazardous Areas Explained

T&D offer a greater, in-depth analysis of hazardous areas and electrical heating in these areas.

Hazardous areas explained

Hazardous areas explained

Hazardous areas are classified into the following zones by their level of toxicity and potential of gas being present and are defined as:

Gases, Vapours And Mists

Zone 1 – Zone 1 hazardous areas are considered to be a place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally. 

Zone 2 – Zone 2 hazardous areas are classified as a place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only. 

Dusts

Zone 21 – A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally. 

Zone 22 – Zone 22 hazardous areas are a place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Equipment that is suitable for use in hazardous areas or that has been specifically manufactured for that purpose will typically have an ATEX hexagon marking on for easy identification and in many cases this marking will include a temperature rating expressed as a “T” marking, and sometimes a gas group.

These indicate limitations to safe use. Employers and those installing equipment should consider the marking and documentation provided with “Ex” equipment when it is being installed.

Hazardous Area Temperature (T) Ratings

In addition to direct ignition sources, hazardous area rated equipment must also meet relevant temperature ratings in order to be classified as safe for use. The temperature should be considered at which a mixture of vapour, gas and dust would ignite and become a self-sustaining reaction in the area in which the equipment would operate.

This temperature (T) rating refers to the maximum outside temperature equipment can reach and is based upon the auto ignition temperature of gases.

Temperature Classification Maximum Surface Temperature, °C Ignition Temperature of gas or vapour, °C
T1 450 >450
T2 300 >300
T3 200 >200
T4 135 >135
T5 100 >100
T6 85 >85

The Range Of Hazardous Area Heating Products From Thorne & Derrick

Heating and air warming is required in many industries where hazardous areas are commonplace. The range of products supplied by T&D offer a full heating solution for almost any requirements. This includes standard product requirements and bespoke solutions.

Thorne & Derrick supply a range of products suitable for use in all hazardous areas. The full range includes:

  • Heat Tracing Cables (Hazardous Area Zone 1 & Zone 2)
  • Portable ATEX Heaters
  • Fluid Control 
  • Air Warmers & Fan Heaters
  • Immersion Heaters
  • Water Heaters
  • Line Heaters
  • Thermostats & Transmitters
  • Heated Hoses
  • Drum Heaters & Heating Jackets
  • IBC Heaters & Heating Jackets
  • Portable Heaters

The standards used when classifying hazardous areas and products vary globally and include ATEX, IECEx, Gost K and Inmetro.

Bartec Hazardous Area Certifications

Hazardous Area Certifications

Video: Hazardous Area Combustible Dust: An Insidious Hazard

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