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Devices for use in explosive atmospheres.

What do Atex standard says?

The Directives set out the basic Safety and Health requirements and entrust EC Standards with the task to express technically their pertaining requisites. Directives apply to safety equipment and systems intended for use in potentially explosive atmosphere within the EU Territory of the EEA. (European Economic Area).Failing both requisites (potentially explosive atmosphere and installation site within the EU makes it inapplicable).The employers (Atex 99/92/EC) and the manufacturers of equipment suitable for installation in such areas (ATEX 94/9/EC) have the obligation to comply with these standards, concerning potentially explosive environment.

This directive is oriented to the employer and specifically referred to the Law 696. It harmonizes and sets out the minimum requirements for the safety and Health protection of workers potentially at risk from explosive atmospheres and involves a number of obligations for the employer, who shall implement some technical / organisation measures in order to:

  • Prevent the formation of explosive atmospheres.
  • Avoid the ignition of explosive atmospheres.
  • Remove dust layers.
  • Provide for proper room ventilation.
  • Prevent the ignition of mechanically generated sparks
  • Increment the size of dust particles
  • Keep out of the gas or dust concentration limits that could give rise to a risk of explosion
  • Install alarm systems to signal for any harmful concentration.
  • Minimize the explosion damages in order to safeguard safety and health of workers.
  • Take prevention and protection measures against explosions.

Such measures have to be adopted and periodically verified whenever relevant changes are applied.

The employer has the obligation to assess/ provide for assessment of explosion risks in the concerned areas as well as in the areas connected, through openings, to the area where explosive mixtures could build up.

To this purpose, the following has e.g. to be considered:

  • Probability and duration of presence of potentially explosive atmospheres.
  • Likelihood they get active.
  • System features, substances used, working processes and interaction.
  • Importance of possible effects.

Note that:

  • The areas with risk of explosion are the ones in which an explosive atmosphere may be expected in such a quantity that safety provisions are to be taken in order to safeguard the health of workers.
  • The areas without risk of explosion are those areas where an explosive atmosphere may be expected in such a quantity that no special protection provision is required.
  • Flammable and/or combustible substances are considered those substances that can give rise to an explosive atmosphere, unless an examination of their characteristics has pointed out that they can produce and explosion if mixed with air.
CLASSIFICATION OF AREA WITH EXPLOSION RISK
Zone 0Explosion risk is continuously actual or persists for long periods of time.Mixture of air + gas, vapour and mist
Zone 1The risk of explosion atmosphere is probable

Mixture of air + gas, vapour and mist

Zone 2The risk of explosion atmosphere is not probable

Mixture of air + gas, vapour and mist

Zone 20Explosion risk is continuously actual or persists for long periods of time.Combustible dust cloud in the air
Zone 21The risk of explosion atmosphere is probable

Combustible dust cloud in the air

Zone 22The risk of explosion atmosphere is not probable

Combustible dust cloud in the air

Zone 0
Zone 20

Category  1

In all areas where a risk of explosive atmosphere persists, must be used protection equipment or systems corresponding to the categories set forth by the Directive 94/9/CE.

Zone 1
Zone 21

Category  1 o 2

Zone 2
Zone 22

Category  1, 2 o 3

The Employer must determine which are the areas where explosive atmosphere could be present and such areas must be signalled with proper warning signs

The Employer draws up AND KEEPS UP TO DATE a document named Explosion Protection Document (EPD); such document shall demonstrate, for instance:

  • That the explosion risks have been identified and assessed, and that measures have been taken to attain safety goals.
  • That places have been classified into zones.
  • That the minimum requirements have been met.
  • That the workplaces and equipment, including alarm systems, have been prearranged with due regard to safety.
  • That arrangements have been made for safe use of the working equipment (in accordance with Directive 89/655/CEE).

The Employer must adopt the following measures to prevent any risk of explosion:

  • To avoid escapes of gas, vapour, mist, powder or electrostatic discharge on control.
  • To operate systems, equipment, protections only if the Explosion Protection Document says it is permissible.
  • To install correct equipment, specially designed and installed to be located in potentially explosive areas.
  • To provide for optical/acoustic devices warning workers before an explosion occurs.
  • To install escape devices for rapid exit from the area.

The Directive 94/9/CE is oriented to the manufacturer; it is specifically related to the Machinery Directive and includes some specific requirements aiming at avoiding risks from potentially explosive atmospheres (while the Machinery Directive includes only general requirements concerning safeties for protection from explosions).

The Directive 94/9/CE sets out the basic safety and health requirements concerning non-electric devices intended for use in potentially explosive atmosphere, and the equipment intended for use in potentially explosive environments due to the presence of dust, as well as protective systems and devices intended for working out of explosive atmosphere, which are useful or essential for safe functioning of the equipment.

The Directive defines the obligations of the person who puts products onto the market and/or puts them into service. It is the manufacturer’s responsibility to verify whether its own product is within the requirements of the Directive 94/9/CE.

In order to verify whether a product is suitable for operating in potentially explosive environments, the manufacturer has to carry out the so-called ATEX Analysis.

He shall consider a series of possible sources of ignition in the environment where his own products are placed and feature the devices so that they cannot be a source for ignition.

Therefore, the manufacturer shall consider:

  • The atmosphere where the product is placed; moreover, according to the zones, the devices shall be properly protected by suitable protective systems.
  • Potential ignition sources as sparks, part temperature, etc.
  • Electrostatic sources of ignition.
  • Storage of light matters as aluminium saw dust, etc.

Owing to the existing law on correlation between employer and manufacturer in conformity with the principles of the Law 626 on Safety and Health Protection of Workers.

Italian Law 626 Title VIII bis Protection from

 Explosive Atmospheres 

Employer

Manufacturer

Directive 99/92/CE dd 16/12/99 G.U.C.E. L 23 dd 18/01/2000

D.P.R. 462 dd 22710/01
G.U.R.I. n.197 del 26/08/2003.

D.legs. 233 dd 12/08/2003 

Directive 94/9CE dd 23/03/94
G.U.C.E. L 100 dd 19/04/1994

DPR 126 dd 23/04/98
G.U.R.I. n.101 dd 04/05/1998

Guidelines May 2002 (n.09/04)

In the light of the above-mentioned correlation, it is necessary that an exchange of information take place between employer and manufacturer that, besides helping the attainment of goals, also limit their responsibilities in a significant and clear manner.

The employer has to inform the manufacturer, on purchase, of the ATEX classified area where the purchased device will be installed.

The manufacturer shall deliver a device certified for the Zone where it has to be installed.

Therefore, it is essential that the employer performs a correct and thorough assessment of the working zone classification.

Often it happens that an employer installs a system in an ATEX zone, which includes components and/or equipment supplied by various manufacturers.

Therefore, such a system is an integration of several products delivered by various manufacturers, and their assembly is carried out by the same user. In this case, the system does not fall within the requirements of the Atex Directive 94/9/CE, even if it must be conforming to all statutory regulations.

On demand all products are available in ATEX version, our Technical Department is at your disposal for more information.

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