ATEX Certification

Eurocert – A Approved Notified body for ATEX

What are ATEX Zones?

ATEX ZONES EXPLAINED

How to decide Which ATEX Certification  marking you require?

This can be quite challenging if you are new to ATEX certification. Below is a guide for selection of Protection marking for various zone

SELECTION GUIDE  FOR  ATEX APPARATUS
ZONE	Marking	Meaning
0 (Category1 equipment Requires a EPL of a)	ia	Intrinsic safety
0(Category1 equipment Requires a EPL of a)	s	Special protection
1(Category2 equipment Requires a EPL of b)	d	Flame proof
1(Category2 equipment Requires a EPL of b)	ib	Intrinsic safety
1(Category2 equipment Requires a EPL of b)	p/p1	Pressurization /Purging for zone 1
1(Category2 equipment Requires a EPL of b)	m	Encapsulation
1(Category2 equipment Requires a EPL of b)	e	Increased safety
1(Category2 equipment Requires a EPL of b)	v	Ventilation for Zone 1
1(Category2 equipment Requires a EPL of b)	s	Special protection for Zone 1
2(Category3 equipment Requires a EPL of b)	n
2(Category3 equipment Requires a EPL of b)	p	Pressurization for Zone 2
2(Category3 equipment Requires a EPL of b)	p1	Purging for Zone 2
2(Category3 equipment Requires a EPL of b)	v	Ventilation for Zone 2
2(Category3 equipment Requires a EPL of b)	s	Special protection for Zone 2

It essentially means that If you are looking to get ATEX certification which is going to be used in Zone 1 then Your Equipment will fall under Category 2 and will require a Explosion protection Level of “b” which can be achieved by many ways as outlined in the middle column above.

What are the Various Gas Groups?

Three Gas Groups are defined

IIA- For Propane
IIB- For Ethylene
IIC- For Hydrogen /Acetylene

Lower Explosive Limit (LEL)

It is  the minimum concentration of  vapor or flammable gas  in the atmosphere below which the gas atmosphere is not explosive.

Upper Explosive Limit (UEL)

It  is the maximum concentration of vapor or  flammable gas  in the atmosphere above which the gas atmosphere is not explosive.

Examples of Explosive Limits

So the above defines the atmosphere ranges which could be explosive and require protection strategies .

MIEC / MIE
Another important concept is MIEC-most easily ignited concentration (MEIC), the amount of energy required to cause ignition is minimal.
The critical energy at the MEIC is called minimum ignition energy (MIE).

What are the Various Temperature Classes? and What is the effect of Temperature in ATEX classification / Certification

All materials have a spontaneous ignition temperature (SIT), also know as  auto ignition temperature (AIT). This is the temperature  at which the material will ignite on its own.

If the temperature of a Gaseous and vapor mixture is raised, the amount of electrical energy required for ignition will reduce, and will be  “zero”  at the AIT.

Temperature Classification

– Equipment is identified with a temperature class
•  Either identified by a ‘T’ rating or by a temperature in degrees C.
-The temperature class identifies the hottest temperature that the equipment can obtain.

What is principle of Intrinsic Safety in ATEX?

This Safety principle is different light from other protection methods. It differs from the various “enclosure” methods where the intent is  to minimize the chances of electrical ignition or minimize its effects. 

Intrinsically Safe’  equipment  means that the equipment is designed for use in hazardous environments / explosive atmospheres. Due to the high levels of combustible substances in these areas, it is essential that such a device guarantees that  no spark is cause  or reaches a high temperature

any equipment which is not marked intrinsically safe may cause a spark and must not be brought onto Zone 0 or 1

A example of this is use of  Zenner Diode Barrier which is an ultra high speed switch and monitoring device. This barrier checks the current drawn by the device in the hazardous area, if the current exceeds a limit defined by the manufacturer – even about40-50 mA – the circuit is “cut” and the  outgoing cables are switched to earth. All this happens within micro-seconds