ATEX, EX, ESD and antistatic products
Read about EX, ESD, ATEX Directive and antistatic products here
This guide examines the understanding and requirements for EX products, ESD and Antistatic products. Also referred to what WEA tutor.
What are the abbreviations for?
Antistatic products are products that protect against sudden discharges of electrostatic energy. EN 1149 prescribes measurement methods for a product electrostatic properties. When a product electrostatic properties may change due to temperature, humidity, etc. estimated from the reported measurement results if the product is suitable.
Extract from WEA guidance on equipment for potentially explosive atmospheres.
Rules and protection principles for equipment
New technical means intended for use in potentially explosive atmospheres, with its own potential ignition source, covered by the Executive Order on the arrangement of technical equipment for use in potentially explosive atmospheres, as well as the Ministry of Housing Order on electrical equipment and electrical systems intended for use in potentially explosive atmospheres. The two regulations implementing the so-called ATEX design Directive in Danish legislation.
Fabrikanter af ovennævnte “ATEX direktiv” skal bl.a.:
- Identify own ignition source of the material
- Prevent the formation of their own potential ignition sources
- Brand materials with correct group category and any limitations (see below)
- and labeling (components must not marked).
Required potential equalization of equipment, and the effects of static electricity must be reduced to a safe level. See Security Agency rules.
Explosive charge of persons with static electricity can be prevented by adequate conductivity of floors in work rooms. The employees must be provided with appropriate personal protective equipment consisting of materials that encourage drainage of static electricity that discharges that can cause an explosion hazard can be avoided. Resistance from person to land should be a maximum of approximately 108 O.
New safety shoes with anti-static properties must meet the requirements of the standard EN 20345-1 Foot. Shoes with antistatic properties are labeled A, S1, S2, S3, S4 or S5. New shoes have a resistance of maximum 100 k ohms, but this may change during use.
Protective clothing with antistatic properties to be used, where appropriate, for example, where the handling of flammable liquids. New protective clothing with antistatic properties must meet the requirements of the standard EN 1149-5 Protective clothing, Electrostatic properties.
Floors are generally sufficient conductivity when they are made of concrete with reinforcement into the soil and an untreated surface. Other arrangements are, however, also provide adequate anti-static properties, for example, coating with semiconducting properties. Regardless of how the floor is made, it is important that the conductivity is controlled by measurements distributed over the entire floor.
Hazardous areas must be marked according to the Ministry of the Interior Decree on the classification of hazardous areas that also contain labeling requirements. The municipal council (in practice rescue services) is the local authority in the area.
When an installation, a workplace or work area is zoned, is a labeling is required to tell everyone in the work that here is a risk of explosion.
The signs are well known, and an example shown on the bottom. They should be placed on all doors to the room / area. Is that a larger area can be marked by inserting yellow warning stripes on the floor. The signs must also meet the Danish Working Environment Authority regulations on safety signs.
Inputs for hazardous areas must be marked with the following yellow warning signs on the right
The sign must be triangular with black letters Ex on a yellow background and black border. The yellow part to take up at least 50 per cent. of the sign. The signs must be of a size and location that is clearly visible when one moves into a hazardous area. The signs should preferably be located at the transition from unclassified to a classified area, but for practical reasons the location of the access door to the room would be acceptable. If not throughout the room, but only part of this hazardous area, that part shall be marked with a yellow / black diagonal stripes on the floor.
At the entrance to the areas and premises with classified areas must also set up clear and durable signs (pictograms) prohibiting smoking and open flames.
This guide examines the understanding and requirements defined in the ATEX directive.
Equipment for hazardous areas
ATEX Directive 94/9 / EC is a Directive adopted by the EU for products for use in potentially explosive environments. It was made (voluntary) 1 March 1996 but only became really into effect. July 1, 2003, when it was enjoined both manufacturers and end customers.
ATEX Directive 94/9 / EC replaces the old "Explosive Atmospheres and Gassy Mines Directive" (76/117 / EC), better known as 'CENELEC directive'.
What is an explosion?
An explosion is a rapid oxidation or decomposition reaction, which gives an increase of temperature, pressure, or both simultaneously.
A vulnerable area / potentially explosive atmosphere is defined as an area where an explosive atmosphere is likely present or is present and to such an extent that ordered special security measures for the composition and use of electrical equipment.
Explosive atmosphere is a mixture of air and flammable gases, vapors, mists or combustible dusts under atmospheric conditions where combustion spreads to the entire unburned part of the mix.
Auto-ignition temperature is the temperature in ° C, whereby a gas will spontaneously ignite without any other type of ignition source.
Because there is no relationship between of ignition energy and the ignition temperature of the array of emissions, has set a temperature classification:
Ex: H2 gas can explode if: (20 μJ or 560ºC)
|Temperature class||Max Temperature( °C.)|
Grouping of gases
Gases are divided into 2 groups based on the LEL and UEL values.
GROUP I: for mines with a risk of methane. (Ignition energy: 200 μJ)
GROUP II: for explosive gases in areas except mines.
- Group II is furthermore divided into three sub-groups:
IIA, for atmospheres containing propane / butane / oil / ammonia or gases with a similar risk. (Ignition energy of 200 μJ = High level, low risk)
IIB, For atmospheres containing ethylene / ether or gases with a similar risk. (Ignition energy of 60 μJ = Medium level, medium risk)
IIC, For atmospheres containing hydrogen / acetylene or gases with a similar risk. (Ignition energy of 20 μJ = Low level, high risk)
ATEX Symbols and codification
The new ATEX Directive shows us the next codification of the product:
The meaning of the symbols you can find below
ATEX zones - Explosive Areas
The directive IEC 60079-10 and 'USE' Directive 1999/92 / EC helps users to know which category their equipment must be, to be used in potentially explosive environments.
ATEX Category 1 (Formerly Zone 0)
Where an explosive atmosphere is constant, or present for long periods (> 1000 t / year).
ATEX Category 2 (Formerly Zone 1)
Where an explosive atmosphere is likely to occur in normal operation. (Between 10 > 1000 t / year) Increased safety under abnormal operating conditions.
ATEX Category 3 (Formerly Zone 2)
Where an explosive atmosphere does not occur during normal operation and if it occurs, it is only a very short time. (< 10 t / year) Equipment which is suitable for normal operating conditions.