Looking for Hazardous (Ex) Area Classification support in Middle-East?
Our Locations: Doha – Qatar, Muscat – Oman, Dubai, Abu Dhabi – UAE, Riyadh, Dammam – Saudi Arabia
We conduct Zone Classification or Hazardous (Ex) Area Classification and issue the classified Drawing & Report.
What is Hazardous Area Classification and Control of Ignition Sources?
Hazardous Area Classification for Flammable Gases and Vapours
Area classification may be carried out on typical Ex installations described in established codes, or by more quantitative methods that require a more detailed knowledge of the plant. The starting point is to identify sources of release of flammable gas or vapour. These may arise from constant activities; from time to time in normal operation; or as the result of some unplanned event. In addition, inside process equipment may be a hazardous area, if both gas/vapour and air are present, though there is no actual release. Some call it as ATEX Zoning / Ex Zoning / Area Classification / IECEx Area Classification
What is Ex Zoning?
Hazardous areas are defined in DSEAR as “any place in which an explosive atmosphere may occur in quantities such as to require special precautions to protect the safety of workers”. In this context, ‘special precautions’ is best taken as relating to the construction, installation and use of apparatus, as given in BS EN 60079 -101.
Area classification is a method of analysing and classifying the environment where explosive gas atmospheres may occur. The main purpose is to facilitate the proper selection and installation of apparatus to be used safely in that environment, taking into account the properties of the flammable materials that will be present. DSEAR specifically extends the original scope of this analysis, to take into account non-electrical sources of ignition, and mobile equipment that creates an ignition risk.
Hazardous areas are classified into zones based on an assessment of the frequency of the occurrence and duration of an explosive gas atmosphere, as follows:
- Zone 0: An area in which an explosive gas atmosphere is present continuously or for long periods;
- Zone 1: An area in which an explosive gas atmosphere is likely to occur in normal operation;
- Zone 2: An area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it occurs, will only exist for a short time.
The most common values used are:
- Zone 0: Explosive atmosphere for more than 1000h/yr
- Zone 1: Explosive atmosphere for more than 10, but less than 1000 h/yr
- Zone 2: Explosive atmosphere for less than 10h/yr, but still sufficiently likely as to require controls over ignition sources.
A hazardous area extent and classification study involves due consideration and documentation of the following: Some call it as ATEX Zoning / Ex Zoning / Area Classification / IECEx Area Classification
- The flammable materials that may be present;
- The physical properties and characteristics of each of the flammable materials;
- The source of potential releases and how they can form explosive atmospheres;
- Prevailing operating temperatures and pressures;
- Presence, degree and availability of ventilation (forced and natural);
- Dispersion of released vapours to below flammable limits;
- The probability of each release scenario.
Ignition Sources - Identification and Control
Ignition sources may be:
- Flames;
- Direct fired space and process heating;
- Use of cigarettes/matches etc;
- Cutting and welding flames;
- Hot surfaces;
- Heated process vessels such as dryers and furnaces;
- Hot process vessels;
- Space heating equipment;
- Mechanical machinery;
- Electrical equipment and lights
- Spontaneous heating;
- Friction heating or sparks;
- Impact sparks;
- Sparks from electrical equipment;
- Stray currents from electrical equipment
- Electrostatic discharge sparks:
- Lightning strikes.
- Electromagnetic radiation of different wavelengths
- Vehicles, unless specially designed or modified are likely to contain a range of potential ignition sources
A hazardous area can be defined as any location where there is risk of an explosion. But every hazardous area is different and each has specific requirements depending on the nature of the atmosphere and the elements that are present.
Fundamentally, for an explosion to take place, flammable or explosive gases, vapours, mists or dusts will be present. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. This level of risk is represented by classifying the hazardous area as Zone 0, Zone 1 or Zone 2 (for gas, vapour and mist atmospheres) or Zone 21 or Zone 22 for dust atmospheres.
In this article we will look at what defines Zone 0, Zone 1 and Zone 2 hazardous area classifications and the considerations for specifying lighting into each area. But first, we must consider what is likely to cause an explosion in the first place. Some call it as ATEX Zoning / Ex Zoning / Area Classification / IECEx Area Classification
There are three necessary components for an explosion to occur;
1. FLAMMABLE SUBSTANCE
This needs to be present in a relatively high quantity to produce an explosive mixture (e.g. gas, vapours, mists and dusts).
2. OXYGEN
Oxygen is required in high quantities and in combination with the flammable substance to produce an explosive atmosphere.
3. IGNITION SOURCE
A spark or high heat must also be present.
Where there is potential for an explosive atmosphere, special precautions are needed to prevent fires and explosions. Electronic equipment, including lighting, needs to be purpose designed for use in hazardous areas to prevent a spark occurring and igniting any flammable substances.
Although every application is different, for the ease of monitoring and specification each hazardous area is classified as a particular level or “zone”. As a result, all hazardous area equipment must be designed with hazardous area zone classifications in mind, as the “zone” governs the level of protection and precaution required. It is essential to know which zone you are working in, so that you can specify the most appropriate equipment.
For gases, vapours and mists the zone classifications are recognised as Zone 0, Zone 1 and Zone 2 areas. Let’s take a look at what defines each zone…
ZONE 0
Zone 0 is an area in which an explosive atmosphere is present continuously for long periods of time or will frequently occur.
ZONE 1
Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. It may exist because of repair, maintenance operations, or leakage.
ZONE 2
Zone 2 is a place in which an explosive atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only. These areas only become hazardous in case of an accident or some unusual operating condition.
To make this even easier to understand, take a look at the diagram of a typical petrol station below where we have identified the areas that are classified as Zone 0, Zone 1 and Zone 2.
Whenever you are filling up your tank you are standing in a Zone 1 hazardous area. That is why the use of mobile phones on petrol forecourts are banned. You’re phone isn’t rated for use in hazardous areas. Have a think about it next time you’re filling up!
Ex i Intrinsic Safety
Ex i is an explosion protection concept in which the electrical energy within the equipment is restricted to a level which is below that what may cause an ignition or to limit the heating of the surface of the hazardous area equipment. There are two main sub types to Ex i protection, these being “ia” and “ib”. Type “ia” protection allows for the occurrence of two faults during operation Type “ib” explosion protection allows for the occurrence of one fault during operation.
Ex d Flameproof
The equipment that may cause an explosion is contained within an enclosure which can withstand the force of an explosion and prevent transmission to the outside hazardous atmosphere. The Ex d flameproof method of explosion protection also prevents the hazardous atmosphere from entering the enclosure and coming into contact with equipment.
Ex m Encapsulation
Ex m is an explosion protection concept where by equipment that could potentially cause an ignition is encapsulated within a compound or resin so as to prevent contact with the explosive atmosphere. The concept also limits the surface temperature of the equipment under normal operating conditions.
Ex e Increased Safety
Ex e is an explosion protection concept applied to the installation to ensure increased security against the possibility of excessive temperatures and sparks from hazardous area electrical equipment. Equipment that normally causes sparks is excluded from use within this method of protection.
Ex p Pressurised
One process ensures that the pressure inside an Ex p enclosure is sufficient to prevent the entrance of a flammable gas, vapour, dust, or fibre and prevent a possible ignition. Another process maintains a constant flow of air (or an inert gas) to dilute to take away any potentially explosive atmosphere.
Ex p Pressurised
Ex m is an explosion protection concept where by equipment that could potentially cause an ignition is encapsulated within a compound or resin so as to prevent contact with the explosive atmosphere. The concept also limits the surface temperature of the equipment under normal operating conditions.
Ex o Oil Immersion
All equipment that has the potential to arc and potentially cause an ignition is immersed in a protective liquid or oil. The oil provides an insulating method to prevent ignition.
Ex q Powder Filling
All equipment that has the potential to arc is contained within an enclosure filled with quartz or glass powder particles. The powder filling prevents the possibility of an ignition.
Ex n Non-Sparking
A type of explosion protection where precautions are taken so that hazardous area electrical equipment that has the potential to arc is not capable of igniting a surrounding explosive atmosphere. This can be further categorised as follows:
Ex nA -Where components used in construction are non-sparking
Ex nC -Where components used in construction are non-incendive
Ex nR – Where components used are tightly enclosed to restrict the breathing and prevent ignition
Ex nL -Where components used in construction do not contain enough energy to cause an ignition
Ex s Special
This method of explosion protection, as its name indicates, has no specific parameters or construction rules. In essence it is any method of explosion protection which can provide a pre-determined level of safety to ensure that there is no potential for an ignition. As such it does not fall under any specific protection method and may in fact be a combination of more than one.
Marking of Hazardous Area Equipment
All equipment for use in hazardous areas should be marked as prescribed in 60079-0. As a general rule this includes, where appropriate, such information as:
– Company/Manufacturers name and address
– Hazardous area certificate number(s)
– Protection concept – Gas group(s)
– Temperature class
– Ambient temperature range
– Product identification
– Serial number and year of manufacture
– Electrical parameters
– CE marking and ATEX notified Body ID number
– ATEX coding – IP code
Marking of Hazardous Location Equipment
The marking of hazardous location equipment varies in accordance with the relevant Electrical Code. As a general rule equipment should be marked as follows:
– Company/Manufacturers name
– Class I, II and/or III
– Division 1 and/or 2
– Group A, B, C, D, E, F and/or G
– Approving NRTL (Nationally Recognized Testing Laboratory) logo
– Product identification
– Serial number
– Other relevant safety information
– Enclosure Type Rating
Our Locations: Doha – Qatar, Muscat – Oman, Dubai, Abu Dhabi – UAE, Riyadh, Dammam – Saudi Arabia
Do all materials in ATEX Zones need to be ATEX certified?
ATEX certification requirements vary depending on the category of equipment and the zones of the equipment’s intended use.
We perform ATEX testing on materials, such as air powered drills or turbine assemblies that are going into an ATEX Zone and can potentially generate and store a static charge. These tests give you confidence in the materials used and the pace of mind. However, as they pose no actual ignition risk in themselves, the products cannot be ATEX certified. For example, with a plastic bucket, although there could be a small buildup of static, the bucket in itself cannot cause a spark or discharge and therefore would not be a risk.
How do I certify non-electrical equipment for use in explosive atmospheres?
All non-electrical equipment that poses an ignition risk needs to be covered by the ATEX Directive and will refer to standards EN 80079-36:2016 and EN 80079-37:2016. Typical non‐electrical equipment which may present a potential danger include motors, gear units, air powered drills, turbine assemblies valves, and rollers.We highly recommended that you design non-electrical products in line with these standards to avoid serious difficulties trying to amend and alter a product after prototypes have been finalized.
How do I certify an ATEX product that I have not manufactured?
When certifying a product over which you have no design control, it is essential to find out whether the product or material that it’s made of has been altered in the design process. If this is the case, manufacturers must confirm that any alterations made fall within the limitations of the standards that a product had initially been certified to. Even then, you may still require to perform an amount of additional testing. Because of this, certifying a product bought off the shelf from another company is extremely difficult and verges on impossible if you do not have a close working relationship with them.
Our Locations: Doha – Qatar, Muscat – Oman, Dubai, Abu Dhabi – UAE, Riyadh, Dammam – Saudi Arabia