Intrinsic Safety – What does it mean? 

Intrinsic safety is an explosion prevention technique used to ensure safe operation of electrical equipment in a hazardous area. This technique uses a low-energy signalling technique that reduces the energy within the equipment to below that required to initiate an explosion, whilst maintaining an energy level this is an be used for its operation.  

What is a hazardous area? 

A hazardous or explosion-prone relates to an environment that has vast amounts of flammable substances such as combustible particles, gases, vapor. Hazardous industrial areas include oil refineries, mining, distilleries and chemical plants. The main safety issue in these industrial scenarios is that of flammable vapours and gases. This is because when they are mix with oxygen within the air, they can establish an explosion-prone environment. Food processing factories, grain handling facilities, recycling operations, and even flour mills generate combustible dust, which is why these are classed as too hazardous locations. Hazardous places are classified in terms of zones on the basis of the frequency and duration of the occurrence of an explosive atmosphere. Areas subject to flammable gas hazards are classified as either Zone 0, Zone 1 or Zone 2. 

How does it work? 

Intrinsic safety prevents sparks and heat from being generated from any electrical equipment, devices or instruments that otherwise ay have initiated an explosion in a hazardous area. Hazardous spaces may belong, but are not limited to, to the following: petrochemical refineries, mines, agriculture grain storage, wastewater, distilling, pharmaceutical, brewing, and utilities. 

Intrinsic safety is achieved with the use of a Zener Diodes which limits voltage, resistors that limit the current and a fuse to cut off electricity. Equipment or devices that may be made intrinsically safe must first be approved for use in an intrinsically safe system through a competent authority, such as the National Fire Protection Agency (NFPA), the Canadian Standards Association (CSA), Underwriters Laboratories (UL), Factory Mutual (FM), National Electric Code (NEC), and the Instrument Society of Measurement and Control (ISA). 

The advantages of Intrinsic Safety 

The main advantage is that it provides a solution to all problems that occur in a hazardous area regarding equipment. It prevents the cost and bulk of explosion proof enclosures, with additional cost savings as a result of the ability to use standard instrumentation cables. Additionally, the maintenance and diagnostic work can be performed without shutting down production and ventilating the work area. 

Levels of protection  

Intrinsic safety relates to three levels of protection, ‘ia’, ‘ib’ and ‘ic’ that aim to balance the probability of an explosive atmosphere, assessing the probability of whether that is an ignition capable situation that may occur. 

‘ia’  

Offers the highest level of protection and any equipment that is given this level is generally considered adequately safe for use in the most hazardous locations (Zone 0) with two faults.  

‘ib’  

This level is considered adequately safe with one fault is considered safe for use in less frequently hazardous areas (Zone 1).  

‘ic’  

This level is given for ‘normal operation’ with a unity factor of safety is generally acceptable in infrequently hazardous areas (Zone 2). 

Level of protection 
Countable faults 
ATEX Category 
Normal Zone of use 
ia 2 1 0
ib 1 2 1
ic 0 3 2

 

To note, although it is normal for a whole system to be allocated a level of protection, it is also possible for different parts of the system to have different levels of protection.  

Why do Gas Certifications matter?

Who Classifies Gas Certificates?

One of the most significant concerns in an industrial workplace is the potential risk of fire or/and explosion. However, there are directives that set standards in which aim to control explosive atmospheres. ATEX (ATmosphere EXplosibles) is the name commonly given to two European Directives for controlling explosive environments. IECEX (International Electrotechnical Commission for Explosive Atmospheres) is the certification that all electrical devices are required to go through by the International Electrotechnical Commission to ensure that they meet a minimum safety standard that will determine whether they can be used in hazardous or explosive environments. For the US Underwriters Limited (UL) is a safety organisation who provide products that are to be sold into the marketplace with authentication that are safe for use. Similarly, the Canadian National Standards (CSA) provide products placed in the market or put into service with a safety certification displaying that they are fit for use. However, The Safety integrity level (SIL) is the level of risk-reduction provided by a safety function, or to specify a target level of risk reduction. The certificates provided by both ATEX and Sil are what operators rely on in order to prevent fires and explosions but also to keep all those in industrial workplaces safe. 

Workplace Hazards

There are too many workplace hazards to count, however, a hazardous location is stated as an area in which combustible or flammable substance is or has the potential to be in attendance. Hazardous locations are specified by the type of combustible hazard and the probability of it being present. These gradings are determined by classifications set by the National Electric Code (NEC) in the United States and the International Electrochemical Commissions (IEC) internationally. These are defined in two ways; either Class/Division system in Northern America or Zones/Groups internationally.  

Class and Divisions

Divisions: 

Division 1: There is a likelihood the hazard is present during normal operating conditions 

Division 2: The hazard is present during abnormal conditions (i.e., In the event of a spill or leak)  

Classes: 

Class 1Gas 

Class 2Dust 

Class 3Fibres  

Zones and Groups 

Zones: identify the possibility for a hazard to be present 

Zone 0: The hazard is in attendance continuously and for a prolonged period of time 

Zone 1: There is a chance that the hazard is in attendance but at normal operating  conditions 

Zone 2: The hazard is not likely in attendance in normal conditions for an extended period of  time 

Groups: Identify the particular type of hazard 

Group 1: Mining Industry hazard specific 

Group 2: Have a group identifying the hazard is gaseous in nature 

A: Methane, propane, and other similar gases 

B: Ethylene and gases or those that pose a similar hazard risk 

C: Acetylene, hydrogen or similar hazards 

Group 3: Dusts and other groups by size of the particle and type of material 

Understanding the Certification Logos

The logos located on the equipment identify who or what association has tested and assessed the equipment, ensuring its safety based on set standards. Many associations will certify equipment as being explosion proof, clarifying that any ignition will be contained within the device and will not pose a threat to the outside environment. This action is intrinsically safe, thereby stopping the device from creating a spark that may lead to an explosion in a hazardous environment.  

Why Certificates are important

Although it is hard to identify all classification, to ensure that equipment has been certified safe, it is essential to look for familiar logos as a primary sign the equipment is safe and won’t pose a threat to the environment. Certificates allow for easy visual for the operator to not only ensure that the devices work correctly but also protect all those in the hazardous environment its set to measure.