Types of protection: Knowing which type

Protection is a method for treating a source of ignition :
- Either by allowing it to be kept in a hazardous zone safely,
- Or by removing it
Protective methods are:
- Established in compliance with European and International Norms
- The way in which the protection is achieved in a sure and reliable way (design, production, testing and certification)

Once all a material’s ignition sources have been treated by applying a protection method, the material can be certified (authorized) and brought into service.

Categories of protection

ELECTRICALComponents for Gases and Vapours
ELECTRICAL Components for Dust
NON-ELECTRICAL Components

Objectives of the different types of protection

To prevent the explosion from propagating, if the explosion occurs due to contact with an ignition source (despite the preventative measures taken).
To remove the ignition source (e.g. prevent the device from heating up or sparks from forming).
To prevent an ignition source from entering into contact with an explosive atmosphere, by preventing the presence of that explosive atmosphere.

Types of ignition protection for electrical equipment

Flameproof enclosure (d)

A type of protection in which the parts which could ignite an explosive atmosphere are placed inside an enclosure which can withstand the pressure of an explosion of the explosive mixture inside, and which prevents the explosion from reaching the explosive atmosphere surrounding the enclosure.

Powder filling (q)

Type of protection in which the parts, which could become an active ignition source, are fixed in their position and completely surrounded by a filling material, thereby preventing the explosive atmosphere from igniting.

Increased safety (e)

Type of ignition protection in which additional measures are taken in order to prevent the possibility of the occurrence of excessively high temperatures and the production of sparks or arcs inside or on the surface of the equipment which are not produced during normal operation.

Intrinsic Safety (i)

An intrinsically safe circuit is a circuit, in which no spark or no thermal effect occurs, which, under the test conditions specified by the norm can cause ignition of a certain explosive atmosphere.

Pressurized enclosure (p)

Use of a protective gas preventing ignition inside an enclosure to prevent the formation of an explosive atmosphere inside the enclosure by maintaining a pressure greater than that of the surrounding atmosphere.

Oil immersion (o)

The electrical equipment is immersed in oil in such a way that an explosive atmosphere which may be located above the oil or outside the encapsulation cannot penetrate or be ignited.

Encapsulation (m)

Type of ignition protection, with which the parts which can ignite an explosive atmosphere through sparking or heating up are embedded in a sealing compound in such a way that an explosive atmosphere cannot penetrate or be ignited.

Product Design (n)

(nA)

Non-sparking

Spark or over-heating protection

(nC)

Sealed device

Protected by a sealed enclosure preventing the explosive atmosphere from penetrating.

(nR)

Restricted Breathing

The enclosures are designed in such a way that the infiltration of gases is restricted.

(nL)

Energy Limitation

(nP)

A flameproof gas is keep under high pressure

Simplified pressurisation

Principle:

Circuit that, in normal use an in certain well-defined fault conditions, cannot ignite the explosive atmosphere.

Types of protection for non-electrical equipment

Flow restricting enclosure (fr)

Type of ignition protection where an enclosure reduces to an acceptable level the probably of infiltration of the surrounding explosive atmosphere into the enclosure by ensuring that the concentration within the enclosure is lower than the lower explosive limit.

Flameproof Enclosure (d)

A type of protection in which the parts which could ignite an explosive atmosphere are located inside an enclosure which can withstand the pressure of an explosion of the explosive mixture inside, and which prevents the explosion from spreading to the explosive atmosphere surrounding the enclosure.

Integrated safety

This type of protection is designed to determine the maximum criteria for the speed of moving parts, for the type of materials and the energy consumed, thereby ensuring that there are no active ignition sources.

Protection by constructional safety (c)

Type of protection in which ignition sources are avoided thanks to rules governing the machine’s design, development, construction, use and maintenance. The construction measures are applied in such a way as to protect the equipment from any ignition generated by moving parts.

Control of ignition source (b)

Type of protection with integrated sensors designed to detect ignition sources and to trigger actions designed to prevent ignition sources from becoming active.

Pressurized enclosure (p)

A protective gas is used to prevent the formation of an explosive atmosphere inside the enclosure surrounding the part by maintaining a pressure greater than that of the surrounding atmosphere. The pressurization is maintained with or without the protective gas flow.

Liquid immersion (k)

Type of protection in which the potential sources of ignition are rendered inactive or are cut off from the explosive atmosphere, either by immersing them totally in a protective liquid or by continuously covering their active surfaces with a protective liquid.

More info

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