Explosion-proof enclosure

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Explosion-proof enclosures are solid cabinets that contain different electrical components like switches, plugs, sockets, transformers, controls, and knobs to keep the surroundings safe from electrical hazards.[1] Integrated with sound technology, these boxes are resistant to spark and shock and have a high tolerance to extreme temperatures. An ideal solution for hazardous locations; these explosion-proof enclosures keep any interior explosion from spreading to the external environment and damaging life and property.

Types of explosion-proof enclosures[edit]

Explosion-proof enclosures are classified into different types depending on the location and the level of protection they offer[2]. These codes are based on National Electrical Manufacturers Association (NEMA) standards which indicate the level of protection against electrical hazards like fire and explosion. Below is a list of location-specific enclosures and their applications:

Non-hazardous locations[edit]

Type 1[edit]

Designed for indoor use, type 1 enclosures offer protection against hazardous parts and protect the electronic equipment from dirt, dust, and debris.

Type 2[edit]

These enclosures are constructed for indoor applications and provide protection to the employees from electric hazards. It keeps the electrical equipment protected from the harmful effects of foreign objects.

Type 3[edit]

Designed for both indoor and outdoor use, type 3 enclosures keep the personnel protected from hazardous parts and the equipment safe from foreign objects and ingress of sleet, snow, dust, dirt, and rain.

Type 3R[edit]

In addition to the features and benefits that accompany Type 1 and Type 2, this make offers a much higher resistance to rain, sleet, snow, dust, and extreme weather conditions.

Type 3S[edit]

Offers protection against hazardous parts and guards the equipment from getting damaged by solid foreign objects. Type 3S enclosures can be used both indoors and outdoors to keep electrical equipment from deteriorating due to the ingress of rain, snow and sleet and functional flaws even when it is fully covered with ice.

Type 3X[edit]

Over and above the protection offered by Type 3R, these enclosures offer a much higher degree of protection against the external environment. The designation X stands for resistance to corrosion.

Type 3RX[edit]

Constructed for both indoor and outdoor use, this specific type offers additional protection against snow, sleet and extreme weather conditions apart from being corrosion resistant.

Type 3SX[edit]

It has all the features and benefits that accompany Type 3S. Designed for rugged use, this make features an efficient external mechanism that is corrosion resistant and facilitates operation even when the unit is covered with snow.

Types 4, 4X[edit]

These enclosures are ideal for both indoor and outdoor use and designed for protection against hazardous parts. These units keep the inside equipment guarded against harsh environmental conditions and ingress of external factors like rain, snow, dirt, dust and sleet. The designation X signifies resistance to corrosion which implies that the enclosure remains undamaged even with the formation of ice.

Type 5[edit]

Type 5 enclosures feature a mechanism that is similar to type 2. It comes with an additional gasket that keeps the enclosure guarded against fibers, lint, dust, dirt, and flyings. It is ideal for indoor use.

Types 6, 6P[edit]

Over and above the safety offered by type 4 units, these have a much higher resistance to water even when there are chances of temporary immersion. It prevents the entry of water and keeps hazardous consequences at bay in case of prolonged immersion.

Types 12, 12K[edit]

Designed specifically for indoor use, these enclosures provide a very high level of protection against dust, dirt, debris, lint, drips, water splashes, fibers, and flyings. Type 12 units are not resistant to rusting and corrosion but 12k units are. 12k enclosures are available in multiple variants including heavy-duty, wall mount, floor mount, modular, consoles, pushbutton and more.

Type 13[edit]

These all-purpose units are specifically constructed for indoor use and provide complete protection against ingress of circulating dust, blowing dirt, debris, lint, fibers, and flyings. It keeps the equipment protected against seepage of non-corrosive coolants, splashing, oil, and dripping.

Explosion-proof enclosures rated for hazardous locations[edit]

Type 7 Enclosures[edit]

Type 7 enclosures are designed for indoor use in Division 1, Class 1, and Groups A, B, C, and D as defined by the National Fire Protection Association.

Type 8 Enclosures[edit]

Type 8 enclosures are designed to meet the needs of indoor as well as outdoor applications in hazardous locations. These units are compatible for use in Division 1, Class 1 and Groups A, B, C, and D.

Type 9 Enclosures[edit]

Compatible with indoor and outdoor installations in hazardous locations, these units are an ideal solution for Division 1, Class 1, and Groups E, F and G.

Type 10 Enclosures[edit]

Type 10 enclosures are designed to meet the safety specifications of Mines and Health Administration as stated under part 18 of CFR 30. Environments that contain combustible substances need multi-rated explosion-proof enclosures. Certain environments may also need high pressurizing and purging, provided there is a dependable system that complies with the safety requirements of National Fire Protection Association (NFPA).

Applications of explosion-proof enclosures[edit]

Explosion-proof enclosures are available in different shapes, sizes, and specifications for different applications. These spark resistant units house electrical equipment and ensure complete safety of surroundings. Typical applications include:

  • Petroleum refineries
  • Industries using flammable liquids for operations
  • Petrochemical industries
  • Dry cleaning plants
  • Fuel servicing areas
  • Gas plants
  • Feed mills
  • Plants running metallurgical processes
  • Chemical plants
  • Producers of plastics and fireworks
  • Producers of medicines, sugar plants, and candies
  • Carbon-handling units
  • Textile mills
  • Flax processing plants

Choosing enclosures for industrial applications[edit]

With more and more companies going green, electronic products are now being designed for use in turbines, solar power systems and alternative energy systems that run with the aid of power and employ smart grids. Faulty installations can lead to fatal injuries and accidents. With the increasing need for electronics in every industry, it is important to consider these five points when selecting enclosures for specific applications:

  • Location

Where the product will be installed determines the level of protection needed. Wind turbines are installed outdoors due to which they need to meet NEMA specifications for which 4X enclosures need to be installed. It is important to determine which enclosure has the required strength and durability to protect the equipment from dripping water, powerful sprays, dirt, dust, snow, sleet and debris depending on the location of installation.

  • Capabilities

The capacity of your chosen enclosure plays a vital role in maintaining safety and speeding installation. The availability of brackets and attachments can be a huge help. It is important to have a mounting panel when installing a variety of electric components. Standard enclosures are readily available and cost much less as compared to customized units.

  • NEMA/RFI Ratings

Applications that involve monitoring and consolidation of excess power from different sources require added protection. A die-cast enclosure made from aluminum with a double layering of gaskets and an outer gasket for sealing the moisture makes an ideal solution for such applications.

  • Dimensions

Apart from environmental safety, you should also consider the future needs of your industry. The scope and extent of expansion play a decisive role in determining the dimensions of the enclosure. A small enclosure may prove to be an excellent space saver but can invite significant expenses in the long run. Enclosure modifications for cable access also need to be taken into consideration in enclosure selection.

  • Design

The appearance of the enclosure becomes particularly important when it is being installed in a home or an office. The material of the enclosure also needs to be selected depending on the end-use. Installing an industrial unit for controlling a domestic solar system is not a sound choice. A plastic unit with a sleek design makes a perfect solution for residential installations.

See also[edit]

References[edit]

  1. ^ "Explosion Proof Electrical Enclosures - D & F Liquidators Inc". dfliq.net.
  2. ^ Hazardous Location Enclosures: The Definitive Guide for 2018, by ISC Sales