hazardous area wiring/eeha optec/agees

Hazardous Area WiringEEHAFUNDAMENTALS

&Tips & Traps

Presented by Dr Rovel Shackleford (EEHA) December 2013 1

Contents

1. History & Introduction2. Dusts & Gases3. The Infernal Triangle4. The Incidents & Accidents keep on keeping on5. Who is RESPONSIBLE6. The STANDARDS7. The REGULATIONS8. The CONSEQUENCES9. Who is LIABLE, Criminal and Civil10. HOW TO BECOME COMPLIANT11. Tips & Traps12. The next STEP (Act NOW)!13. Useful Resources

Presented by Dr Rovel Shackleford (EEHA) December 20132

HistoryThe UKOne hundred years ago, the UK's worst mining disaster happened when 440 people were killed by an explosion which ripped through the coal mine at Senghenydd, near Caerphilly.It was the morning of Tuesday 14 October 1913. The 950 miners working at the Universal Colliery had just started their shift. The blast was so strong, it lifted a two‐ton lift cage hundreds of yards up one of the mineshafts into the headgear. Windows were smashed on Coronation Terrace, half a mile away and the blast was heard many miles beyond that.ChinaThe Benxihu colliery disaster in China cost 1,549 lives and is believed to be the worst coal mining disaster ever. The tragedy occurred on 26 April 1942 in the Honkeiko coal mine, located near Benxi in the Liaoning province of China.http://www.mining‐technology.com/features/feature‐world‐worst‐coal‐mining‐disasters‐china/


• Deadly mix• Methane, the main component of natural gas, is combustible, and mixtures of about 5 percent to 15 percent in air are explosive.

When air contains approximately 9.5 percent of methane (the most dangerous concentration), it reaches the perfect oxidationpoint, which means that the right amount of fuel is mixing with the right amount of oxygen, said. This produces water, carbondioxide and a lot of amount of heat.

• It does not [require] much heat to ignite the combustion process and therefore methane explosion can accelerate very fast.

• The heat generated by this process raises the temperature of the air within the mine, which causes it to expand in volume. Sincehot air cannot expand easily underground, pressure builds in the mine. If this pressure is high enough, it can cause the air aheadof the combustion zone to compress and cause a shock wave.

• Ventilation is the most common method to avoid such methane explosions in coal mines. Large fans are used to blow air out ordraw air into mines.

• Mine explosions can also be triggered when fine particles of coal dust come into contact with a source of heat.

• While methane is easier to ignite, the explosion pressure and heat value of methane is not as high as coal dust. In most cases,dust explosions are first caused by methane explosions.

• "Dust explosion needs a very high concentration of dust suspended in the air, which is very hard to find in a mine environment.

• But, the shock wave caused by methane explosions can blow up coal dust within the mine, and the heat generated by themethane reaction can ignite the dust, which greatly intensifies the energy of the explosion.

Why Do Coal Mines Explode?


The SparkSoon after the introduction of electric power into coal mines, it wasdiscovered that lethal explosions could be initiated by electrical equipmentsuch as lighting, signals, or motors. The hazard of fire damp or methaneaccumulation in mines was well known by the time electricity wasintroduced, along with the danger of suspended coal dust. At least twoBritish mine explosions were attributed to an electric bell signal system. Inthis system, two bare wires were run along the length of a drift, and anyminer desiring to signal the surface would momentarily touch the wires toeach other or bridge the wires with a metal tool. The inductance of the signalbell coils, combined with breaking of contacts by exposed metal surfaces,resulted in sparks which could ignite methane, causing an explosion.

Introduction


DUST

Dust are, from the point of view of a dust explosion,particles of the diameter lower than 0,5 mm. It mustbe also considered that in the mixture of particles oflower and higher size, also bigger particles will takepart in the process of explosion. The lower particleswill burn faster than the bigger ones.Fibres and pulps (of cotton, paper and other suchmaterials) are also considered as dust in the point ofexplosion if it is fine enough to be ignited.


GASES

Gaseous explosive atmospheres consists of atleast one explosive gas and/or vapours offlammable liquids (including aerosols and mists).Their main advantage is their homogeneity inclosed vessels (where there is no strong airflow)which means expectable and calculableconcentration which will be constant in the wholevolume.On the other side, gaseous atmospheres aremuch easier ignitable (with low concentration andby source of small energy, comparing to dustatmospheres).Presented by Dr Rovel Shackleford (EEHA) December 2013

7

Infernal Triangle (DUSTS)

For any fire to occur, there must be fuel, ignition and oxygen (Classic Fire Triangle). However, for a combustible dust explosion, you must also add dispersion and confinement — the “Dust Explosion Pentagon.” Removal of any one element prevents an explosion, though not necessarily a fire.


Infernal Triangle (GASES)

The fire triangle or combustion triangle is a simple model for understanding the ingredients necessary for most fires. It has been replaced in the fire fighting and protection industry partially by the fire tetrahedron.The triangle illustrates a fire requires three elements: heat, fuel, and an oxidizing agent(usually oxygen). The fire is prevented or extinguished by removing any one of them. A fire naturally occurs when the elements are combined in the right mixture.


Classified AreasFlammable Gases and Vapour's Combustible Dusts

• Zone 20 An area in which combustible dust, as a cloud, is present continuously or frequently, during normal operation, in sufficient quantity to be capable of producing an explosive concentration of combustible dust in a mixture with air.

• Zone 21 An area, in which combustible dust, as a cloud, is occasionally present during normal operation, in a sufficient quantity to be capable of producing an explosive concentration of combustible dust in a mixture with air.

• Zone 22 An area, in which combustible dust, as a cloud, may occur infrequently and persist for only a short period, or in which accumulations of layers of combustible dust may give rise to an explosive concentration of combustible dust in a mixture with air.

• Zone 0 An area in which an explosive atmosphere is constantly present, or present for long periods.

• Zone 1 An area in which an explosive atmosphere is likely to occur in normal operation. (Rough Guide: 10 hours or more / year but less than 1,000 hours / year)

• Zone 2 An area in which an explosive atmosphere is not likely to occur in normal operation and if it occurs it will exist only for a short time. (Rough Guide: Less than 10 hours / year)


The Incidents & Accidents keep on keeping on

Imperial Sugar Refinery Explosion2008

Texas City Refinery Explosion2005

http://www.hazardexonthenet.net/


Who is RESPONSIBLE

• Design,• Specify,• Install,• Commissioning,• Inspection,• Audit.

• Asset Owner• Supplier,• Electrical Engineer,• Mechanical Engineer,• Electrical Fitter,• Electrician,• Auditor,• Regulator.

Do YOU see your job role here; if so YOU are responsible!


The STANDARDSMake sure that YOU are aware of the current Local Regulations and Standards that are required to guide your work in Hazardous Areas/ EEHA.

THERE IS NO EXCUSE!


The REGULATIONS

Make sure that YOU are aware of the current Local Regulations and Standards that are required to guide your work in Hazardous Areas/ EEHA.

THERE IS NO EXCUSE!


The CONSEQUENCES

• YOU – could be liable,• YOU – could lose your home and your assets,• YOU – could go to jail for involuntary manslaughter or criminal

negligence,• YOU – could be fined a considerable amount,• YOU – may have to live with the knowledge that YOU were

responsible for the loss of life and livelihood of many people.ARE YOU RESPONSIBLE?Presented by Dr Rovel Shackleford (EEHA) December 2013 15

Who is LIABLE, Criminal and Civil

In the event of a catastrophic failure the CORONER will be investigating to determine the cause of the incident and whom is responsible. The CORONER will determineIf there has been criminal negligence and then refer the matter to the criminal court system. Every rock will be turned over ever work practice associated with that site will be investigated; as they say in the classics you can run but you cannot hide.

Depending on the findings of the Coroners Court either criminal proceeding will occur and or civil proceedings. The outcomes could be a jail term loss of assets, fines; essentially a considerable amount of unpleasantness for YOU!.


HOW TO BECOME COMPLIANT

• TRAINING – undertake the training necessary to ensure that you are qualified to design, select, install, commission and inspect all items and apparatus within EEHA/HAW Classified Areas ( in many countries this training is mandatory!)

• REGULATIONS – ensure that you are aware of the regulations of the country that you will be undertaking EEHA/HAW work (many suppliers ignore this important matter)

• STANDARDS – make sure you are aware of the IEC and all relevant Standards in the country where you will be undertaking EEHA/HAW Work.

IGNORANCE IS NO EXCUSE


Tips & TrapsTIP – understand exactly what the gases and dusts are present in the Classified Areas. Understand the protection techniques required.Understand the dynamics in the industrial environment within which you will be working and select the correct equipment. ASSUME NOTHING!!!TRAP – other technicians non-

compliant Workmanship. READ the manufacturers specifications prior to undertaking the installation!Make sure you have the correct tools including torque wrenches and drivers. ASSUME NOTHING


The next STEP (Act NOW)!

Undertake the required TRAINING NOW!

Get the latest copy of the REGULATIONS for your Country or Region

Get the latest copy of the RELEVANT STANARDS

Take responsibility for YOUR ACTIONS now and work smart to protect yourself and your colleagues and the general public from a potential disaster!


Useful Resources

• TRAINING – Optec at [email protected] M:+61438383836• Hazard EX – http://www.hazardexonthenet.net/• IEC – http://www.iec.ch/• CSB USA – http://www.csb.gov/

• TRAINING – Optec at [email protected] M:+61438383836


hazardous area wiring/eeha optec/agees

Education

dust dust

dust explosions

methane explosions

dust atmospheres

combustible dust explosion

dr rovel shackleford

percent of methane

high concentration of