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What is Explosion Proof (Ex-Proof)?
Jan 11, 2017

The concept of explosion proof doesn’t mean that it can prevent or withstand an external explosion. It simply will contain any explosion originating within the housing and prevent sparks within the housing from igniting vapors, gases, dust or fibers in the air surrounding it.

There are two directives when dealing with ex-proof equipment – the ATEX and the IECEX. Further explanation for these certificates can be found from another blog entry titled “What are ATEX and ICEX Certification?

There are six types of area classification guide to classify explosion-proof environment:

  1. Type of protection

 

 

New Number (IEC)

General rules

 

EN-60079-0

Oil immersed

Ex “o”

EN-60079-6

Pressurization

Ex “p”

EN-60079-2

Power filling

Ex “q”

EN-60079-5

Flameproof enclosure

Ex “d”

EN-60079-1

Increased safety

Ex “e”

EN-60079-7

Intrinsic safety

Ex “i”

EN-60079-11

Non sparking

Ex “n”

EN-60079-15

Encapsulation

Ex “m”

EN-60079-18

 IEC stands for International Electrotechnical Commission, a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology".

  1. Equipment group

Place of use

Group

Areas

Representative gas

Mines susceptible to firedamp

I

Gaseous Mines

Methane

Surface industries

II A

Surface

Propane

II B

Ethylene

II B + H2

Ehtylene, Hydrogen

II C

Hydrogen, Acetylene

  1. Equipment protection level (gas/dust)

Gas Atmosphere

Zone 0

An area in which the mixture of explosive gas is constantly present (ex. the inside of a fuel tank).

Zone 1

An area in which a mixture of explosive gas may be present during the normal operation of the plant.

Zone 2

An area in which the mixture of explosive gas is not normally present, but is only present for brief periods of time.

Dust Atmosphere

Zone 20

An area in which the mixture of explosive powder is constantly present (ex. the inside of fuel tank).

Zone 21

An area in which a mixture of explosive powder may be present during the normal operation of the plant.

Zone 22

An area in which the mixture of explosive powder is not normally present, but is only present for brief periods of time.

  1. Temperature class

Temperature class

T1

T2

T3

T4

T5

T6

Maximum Surface

450oC

300oC

200oC

135oC

100oC

85oC

 

  1. Ingress protection (IP)

First figure indicates protection against dangerous access and solid foreign objects

Index

IP

Index

Second figure indicates protection against water penetration

Non-protected

0

 

0

Non-protected

Protected against solid objects 50 mm Ø or more

1

 

1

Protected against vertically falling water drops

Protected against solid objects 12.5 mm Ø or more

2

 

2

Protected against vertically falling drops water enclosure tilted up to 15º

Protected against solid objects 2.5 mm Ø or more

3

 

3

Protected against spraying water up to 60º from vertical

Protected against solid objects 1 mm Ø or more

4

5   4

4

Protected against splashing water from any direction

Dust-protected

5

5

Protected against jets of water from any direction

Dust-tight

6

 

6

Protected against powerful jets of water from any direction

7

Protected against immersion

8

Protected against continuous immersion

The minimum requirement for Explosion-Proof protection is IP54.

 Supermec mostly caters to Ex “d” and Ex “e” types of protection. The table below shows the advantages and disadvantages of the two:

 

Advantages

Disadvantages

Ex “d”

1. capable of withholding a possible internal explosion and prevent its transmission to the atmosphere outside the housing

2.  higher class of protection

3. easily available and cheaper components

1. maintenance more complicated ( e.g. difficult to change fluorescent tubes)

2. piped plant (where requested) complicated

Ex “e”

1. easy installation

2. pleasant appearance

3. safety cut-off switch

1. high cost of spare parts (components must be Ex type)

2. frequent and costly maintenance (e.g. seal)

 As the leader in the hazardous environment providing safety solutions, Supermec has a wide range of ex-proof products that can cater to our clients’ needs. We have lighting fixtures, control stations, enclosure boxes, plugs and sockets, cable glands, adapters and plugs.


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