Welcome to our comprehensive guide on understanding Class 1 Div 1 and Class 1 Div 2 hazardous location classifications. In many industries, dealing with hazardous environments is an essential aspect of ensuring workplace safety. Proper classification of these locations is crucial to mitigate risks and prevent accidents.

In this guide, we will delve into the differences between these two classifications, their significance, and protection methods used to ensure the safety of both employees and equipment. Our goal is to provide you with a clear understanding of these essential safety measures and their role in various industries.

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Difference Between Class 1 Div 1 and Class 1 Div 2

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Class 1: Flammable Gases, Vapors, and Liquids

Definition and Characteristics of Class 1 Locations

Class 1 hazardous locations are areas where flammable gases, vapors, or liquids exist or have the potential to exist under normal operating conditions. These substances pose a risk of explosion or fire if they come into contact with an ignition source, such as a spark or high temperature.

The primary factor that defines a Class 1 location is the presence of flammable materials in the atmosphere. Which can be further divided into Divisions and Groups based on the likelihood and nature of the hazardous substances.

Common Examples of Class 1 Environments

A wide range of industries and applications may involve Class 1 hazardous locations. Some common examples include:

  • Oil and Gas Industry: Oil refineries, drilling platforms, and processing plants often involve the production, storage, and handling of flammable gases and liquids.
  • Chemical and Petrochemical Industry: Facilities that produce, store, or handle flammable chemicals or solvents can create hazardous environments due to the presence of flammable vapors.
  • Pharmaceutical Industry: The manufacturing and processing of pharmaceuticals may involve the use of flammable solvents or chemicals, creating potential Class 1 locations.
  • Fuel Storage and Distribution: Facilities for storing and distributing fuels such as gasoline, diesel, or aviation fuel are likely to have Class 1 locations due to the flammability of these substances.
  • Paint Manufacturing and Application: The production and application of paints and coatings may involve flammable solvents or vapors, which can create hazardous environments.
  • Wastewater Treatment Plants: The presence of methane gas produced during the decomposition of organic matter can result in Class 1 locations in certain areas of wastewater treatment plants.

It is important to note that not all areas within these industries or facilities are classified as Class 1 hazardous locations. The specific classification depends on factors such as the type and concentration of flammable substances and the likelihood of their presence under normal operating conditions.

Definition and Criteria for Class 1 Div 1 Classification

Class 1 Division 1 (Class 1 Div 1) locations are hazardous areas where flammable gases, vapors, or liquids are present or likely to be present continuously, intermittently, or periodically during normal operations.

The key factor differentiating Class 1 Div 1 from Class 1 Div 2 locations is the higher probability of hazardous substances being present, which results in a greater risk of explosion or fire. In these environments, special safety measures and equipment are required to prevent accidents and protect workers.

Definition and criteria for Class 1 Div 2 classification

Class 1 Division 2 (Class 1 Div 2) locations are hazardous areas where flammable gases, vapors, or liquids are not typically present during normal operations. But may exist under abnormal conditions, such as equipment failures, leaks, or process upsets.

The main difference between Class 1 Div 1 and Class 1 Div 2 locations is the lower likelihood of flammable substances being present in Class 1 Div 2 environments. Despite the lower risk, safety precautions and specialized equipment are still necessary to prevent accidents and protect workers in these areas.

Class 1 Div 2 locations can also be areas adjacent to Class 1 Div 1 locations where flammable substances might escape due to a failure in a containment system or during maintenance activities. In these cases, the hazardous materials are not expected to be present in concentrations that pose a risk of ignition under normal operating conditions, but the potential for their presence still warrants the classification as Class 1 Div 2.

Difference Between Class 1 Div 1 and Class 1 Div 2

The primary difference between Class 1 Div 1 and Class 1 Div 2 locations lies in the risk levels associated with the presence of flammable substances.

Class 1 Div 1 locations have a higher likelihood of flammable gases, vapors, or liquids being present during normal operations, resulting in a greater risk of explosion or fire.

In contrast, Class 1 Div 2 locations are areas where flammable substances are not typically present during normal operations but may exist under abnormal conditions, such as equipment failures or leaks.

The definitive reference is the National Electrical Code Chapter 5.

Due to the differences in risk levels, the protection methods employed in Class 1 Div 1 and Class 1 Div 2 locations also vary.

Some common distinctions in protection methods include:

Explosion-proof enclosures: Used in Class 1 Div 1 locations, these enclosures are designed to withstand an internal explosion and prevent the ignition of flammable substances in the surrounding atmosphere. In Class 1 Div 2 locations, explosion-proof enclosures are not always necessary, as the risk of explosion is lower.

Intrinsic safety: Intrinsic safety measures, such as limiting electrical energy to levels below the ignition threshold, are more commonly applied in Class 1 Div 1 locations due to the higher risk. While these measures can also be used in Class 1 Div 2 locations, other protection methods. Such as non-incendive equipment, may be more appropriate.

Non-incendive equipment: Used primarily in Class 1 Div 2 locations, non-incendive equipment is designed to prevent sparks or high temperatures that could ignite flammable substances under normal operating conditions. This equipment may not be suitable for Class 1 Div 1 locations due to the higher risk levels.

explosion proof enclosure

You also need to consider explosion-proof requirements when purchasing instruments. For example, our pressure transmitters, flow meters, level meters, etc. all have explosion-proof standards. Explosion-proof products will also be equipped with explosion-proof casings. The explosion-proof instrument housings provided by Sino-Inst generally have the “EX” explosion-proof mark.

Explosion-proof enclosures should obtain appropriate certifications, such as ATEX (Europe), IECEx (International), NEC/CEC (North America), to ensure that they can be used safely in specific hazardous environments.

explosion proof enclosure 2
explosion proof enclosure 1

Explosion-proof shells usually adopt one of the following explosion-proof principles:

  • Explosionproof type (Ex d): Able to withstand the pressure of internal explosions and prevent internal explosions from igniting gases in the external environment.
  • Increased safety type (Ex e): non-spark design, its structure ensures sufficient safety increment to prevent ignition of surrounding explosive gases.
  • Intrinsically safe (Ex i): Ensures that any electrical equipment in the circuit will not produce sparks or thermal effects sufficient to ignite surrounding gases.
  • Positive pressure type (Ex p): By maintaining the pressure inside the casing higher than the surrounding environment, it prevents harmful gases from entering the inside of the casing.
  • Non-ignition type (Ex n): Designed to ensure that it will not ignite surrounding explosive mixtures under normal operating conditions.

More Measure and Control Solutions

This guide explores the differences between Class 1 Div 1 and Class 1 Div 2 hazardous location classifications. Class 1 Div 1 locations have a higher likelihood of flammable substances being present during normal operations, while Class 1 Div 2 locations pose a with lower risk, Substances potentially present only under abnormal conditions.

The protection methods used in these locations differ accordingly, with Class 1 Div 1 requiring more stringent safety measures.

To determine the appropriate classification, factors such as the type and concentration of flammable substances, frequency and duration of exposure, and potential for abnormal conditions must be considered.

If you choose pressure, liquid level, flow and other measuring instruments for use in hazardous locations, please inform us in advance. We can configure explosion-proof products for you.

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