Area Classification
Basic Awareness Training for all Staff
Explosion!
Oxygen Ignition
* Flammable Material
* plus
* Oxygen
* plus
* Source of Ignition
Flammable Material
Properties of Materials
Oxygen Ignition
*Flash Point
* Auto Ignition Temperature
* Flammable Range - % Volume
* Gas / Vapour Density - Air = 1
* Source of Ignition
Flammable Material
ZONE DEFINITIONS* Zone 0
* A Zone in which an explosive atmosphere is continuously present, or present for long periods. (> 1000 hours per year)
* Zone 1
* A Zone in which an explosive atmosphere is likely to occur in normal operation.
(10 to 1000 hours per year)
ZONE DEFINITIONS* Zone 2
* A Zone in which an explosive atmosphere is not likely to occur in normal operation, and if it occurs it will only exist for a short time.
* (1 to 10 hours per year)
* NON-HAZARDOUS AREA
* An area in which an explosive gas/air mixture is not expected to be present in quantities such as to require special precautions for the construction, use and maintenance of electrical equipment.
ZONE LOCATIONS* Zone 0* Inside a solvent tank or solventbased manufacturing vessel
* Zone 1* Solventbased paint production areas, around mixers, filling machines, dispersers, etc.. Up to 1.5 to 2m from the floor (vapours are heavier than air) .
* Zone 2* Drum park, warehouse, upper part of production areas, generally around and beyond zone 1, lab benches and floors to 0.5m high.
ZONE DEFINITIONS* Zone 2
* A Zone in which an explosive atmosphere is not likely to occur in normal operation, and if it occurs it will only exist for a short time.
* (1 to 10 hours per year)
* NON-HAZARDOUS AREA
* An area in which an explosive gas/air mixture is not expected to be present in quantities such as to require special precautions for the construction, use and maintenance of electrical equipment.
Registration.
A Register of all electrical equipment in hazardous areas will be held in the Engineering Department by the Site Responsible Engineer or Responsible Engineer.
Each electrical system shall carry a unique reference number.
Up to date listings are to be maintained.
Any new electrical system must be identified and recorded on theRegister in order to ensure that it is regularly inspected.
Electrical Equipment Register
* Use of electrical items
* Avoidance of static electricity - USE EARTHING LEADS
* Control of visitors / equipment (hot work certificate)
* Maintenance work on electrical items. (hot work certification)
* Modification of electrical items
* Damage to electrical items
* Fastening / enclosure of electrical items
* Vehicles (hot work certificate)
IMPLICATIONS OF AREA CLASSIFICATIONS
Show the location and vertical and horizontal extent of the zone 0, 1 and 2 areas.
Where is your area classification drawing?
Make sure it is up-to-date, and consulted by people issuing permits to work.
Area Classification Drawings
Labelling of Equipment
E = European StandardEx = this equipment has some form of
hazardous area protectionia, ib, d, e, n, etc.. = type of protectionIia, Iib, Iic = gas groupT1, 2, etc = temperature rating Certificate numberCertifying body
Electrical Equipment* Zone 0- Ex ia Exs
* Zone 1- Exa Exib Exp Exe Exs Exd * Zone 2- Ex N Ex o Ex q
EEx i Intrinsic Safety
Non Haz Hazardous
Instrumentation
EEx i Intrinsic Safety
Non Haz Hazardous
Incapable of causingan explosion
Inductance and capacitance are limited
Specific fault conditions
EExd Flameproof Enclosure
L
W
• Gas Inside
• Internal Explosion
• Withstands Pressure
• No flame or heat transmission to outside
• Strength must not be reduced
Eexd Flameproof Enclosure
w
Motors
L
Light Fittings
Pushbuttons
Ammeters
Switchgear
EExd Flameproof Enclosure
w
Bolt sizes and length
Covers
L
Glands
Flange Integrity
Surfaces - Clean-Cooling
EEx e Increased SafetyEnclosure
w
By Design
No excess temperatures
No Arcs or sparks
L
EEx e Increased SafetyEnclosure
w
Terminal and connectionboxes
Outer boxes of devices with other
protection eg. EEx ed Lights
Motors - Germany
L
EEx q Powder Filling Enclosure
Transformers,Capacitors,ElectronicAssemblies, ie.Laboratory Balances
EEx q Powder Filling Enclosure
Potentially sparking equipment under finely granulated material.
No explosion generated even though there may be a spark
EEx p Pressurised Apparatus
Fresh air, inert gas or other suitable gas
Higher pressure than surrounds
Initial purge then maintain the pressure
Eex p Pressurised Apparatus
Switch rooms
Control Panels
Fork Lift TrucksSome individual Instruments
Some Motors
Eex o Oil Immersion Enclosure
Potentially sparking parts immersed in oil
The explosive atmosphere cannot reach the incendive parts
Transformers-rarely used now
Ex m Moulding
Potentially sparking parts are enclosed in Resin
No explosion due to sparking or heating within the resin
Ex m Moulding
Only small capacity switch gear, controlgear, indicating equipment sensors