The work of CEN/TC 305

Potentially explosive atmospheres-

Explosion prevention and protection

Chair: Siegfried Radandt(FSA)

Secretary:Rainer Schmidt(DIN)

Available Structures:

• WG1: Test methods for determining the flammability characteristics of substances in potentially explosive atmospheres( data for risk assessment and design of devices and systems for explosion prevention and protection )

• WG2:Equipment for use in potentially explosive atmospheres

• WG3: Devices and systems for explosion prevention and protection

• WG4: Terminology and methodology( e.g.risk assessment methods )

• WG5: Equipment and protection systems for mining

Characteristics of combustable substances for risk assessment, design of equipment, design of protective systems

• Dust clouds:– Determination of maximum explosion pressure– Determination of limiting oxygen concentration– Determination of minimum ignition energy– Determination of the maximum rate of pressure rise of

an explosion– Determination of the minimum explosive concentration

of dust clouds– Determination of the spontaneous ignition behaviour of

dust accumulations

Characteristics of combustible substances for risk assessment, design of equipment, design of protective systems

• Gases and vapours:– Determination of the maximum rate of pressure rise of

an explosion

– Determination of the maximum explosion pressure

– Determination of the lower and upper explosion limits

– Determination of the minimum ignition temperature

– Determination of the limiting oxygen concentration

Specifications for the design of non electrical equipment, components,

elements of machinery• Basic method and requirements

– Ignition hazard assessment,temperatures, non metallic parts,– Equipment containing light metals,removable parts,verification and tests

• Protection by flow restricting enclosures• Protection by flame proof enclosures• Protection by inherent safety

– Maximum energy and speeds

• Protection by constructional safety– Moving parts, bearings, power transmission systems, clutches and couplings, brakes, springs

and absorbing elements, conveyor belts

• Protection by control of ignition sources(sensors,actuators)• Protection by pressurisation• Protection by liquid immersion• Safety requirements for ignition protected fans

Specifications for the design of protective systems

• Explosion suppression systems• Explosion resistant equipment• Explosion venting devices• Dust explosion venting protective systems• Gas explosion venting protective systems• Explosion isolation

• New work item as TR: Inertisation ( should not be mandated )

Definitions, methodologies, procedures, connections

• Terms and definitions• Methodology for risk assessment of equipment• Methodology for risk assessment of protective

systems• Requirements of quality systems• Explosion prevention and protection- Basic

concepts and methodology ( revision of EN 1127 -Part1)

Specific methods and requirements for prevention and

protection in mines• EN 1127 Part 2 ( Basic concepts )• Explosion barriers• Water troughs for explosion barriers• Equipment for firedamp drainage• Automatic explosion installation at road headers• 2-bar explosion proof ventilation structure• Machines for underground mines-Requirements

for application in areas with firedamp hazards

State of Work

Available Documents: 4 ; Formal Vote: 5 ; Enquiry: 13 ; Working Dokuments: 15

Back ground Information about the User of Standards

• RASE Project ( EU Project : SMT4-CT97-2169 )

• Title: Explosive atmospheres: risk assessment of unit operations and equipment

• First Task: Inquiry on current experience from manufacturers

• Second Task: Methodology for the risk assessment of unit operations and equipment

The main job of the firms

• Manufacturers: 86%

• Suppliers: 72%

• Engineering contractors: 34%

The number of employees

• 5% of the inquired firms have less than 10 employees

• 44% of the inquired firms have a number of employees between 10 and 99

• 41% of the inquired firms have a number of employees between 100 and 499

• 10% of the inquired firms have more than 500 employees– That means that 90% are SMEs -