In order to form an explosive atmosphere, the substances in question must be flammable and can be in the form of powder, gas or liquid. Typically, these flammable or explosive substances are explosive as a dust-air mixture if their particle diameter is less than 500 µm. However, some dusts can even be explosive up to a grain diameter of 1 mm.

Flammable solids:

• Plastics
• Organic substances (flour, coffee, starch, cellulose …)
• Metals (aluminum, magnesium …)

Flammable gases:

• Natural gas
• Hydrogen
• Acetylene

Flammable liquids:

• Disinfectant
• Organic solvents
• Treibstoffe

Primary explosion protection
The primary explosion protection principle refers to the preventive avoidance of an explosive dust-air mixture and special protective measures. Primary explosion protection is considered the most reliable technique to avoid explosions.

All extraction systems from ABSAUGWERK are built according to the primary explosion protection principle and can also be operated indoors.

• Correct interpretation of the recording according to BGR 109-001
• Air speeds over 20 m/s (collection, pipe system, extraction system)
• Correct planning of the pipe system (smooth pipe, radii for branches and pipe bends)
• Material separation by cyclone
• Offline cleaning
• Precoating agent

Secondary explosion protection
With the secondary explosion protection principle, ignition is prevented by any potential ignition sources in the hazardous area, but the explosive atmosphere (dust-air mixture in an explosive concentration) remains.

• Avoiding sources of ignition, e.g. due to static charging
• Grounding of pipe system and extraction system
• No sucking in of metallic objects
• Ignition source-free components e.g. ATEX motor to Zone 22

Tertiary explosion protection
Tertiary explosion protection is understood to mean constructive explosion protection. Measures and protective devices, such as rupture disks, are used to limit the effects of explosions. Extraction systems that use this technology can generally incur high follow-up costs for spare and wear parts.

The ATEX Product Directive 2014/34/EU applies to the placing on the market of devices and products in potentially explosive atmospheres. The directive applies to all equipment and protective systems for potentially explosive atmospheres that have been sold in the EU since 2014. In order to comply with the regulations, extraction systems must be designed to be ignition source-free and conductive, and special ATEX components (e.g. motors) must be used; the manufacturer is responsible for compliance with the regulations.

Potentially explosive atmospheres are divided into zones based on the frequency and duration of the occurrence or presence of explosive atmospheres. The necessary measures are defined in accordance with Directive 1999/92/EC, which applies in all EU Member States.

For dusts, zones 20, 21 and 22 are relevant:

Zone 20
is a place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, for long periods or frequently.

Zone 21
is a place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

Zone 22
is a place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

The following Technical Rules for Industrial Safety (TRBS) and for Hazardous Substances (TRGS) contain information on explosion protection (ATEX):

TRBS 1112 Part 1:
Explosion hazards during and due to maintenance work – Assessments and protective measures.

TRBS 1122:
Modifications to gas filling systems, storage systems, filling stations, filling stations and airfield refueling systems – Determination of the obligation to inspect in accordance with Annex 2 Section 3 BetrSichV and the obligation to obtain a permit in accordance with § 18 BetrSichV

TRBS 1123:
Modifications of systems in potentially explosive atmospheres requiring testing – Determination of the need for testing in accordance with § 15 Para. 1 BetrSichV

TRBS 1201 Part 1:
Testing of systems in potentially explosive atmospheres

TRBS 1201 Part 3:
Repair of equipment, protective systems, safety, monitoring and control devices as defined by Directive 2014/34/EU

TRBS 2152/TRGS 720:
Hazardous explosive atmospheres – General

TRBS 2152 Teil 1/TRGS 721:
Hazardous explosive atmospheres – Assessment of explosion hazards

TRBS 2152 Teil 2/TRGS 722:
Prevention or limitation of hazardous explosive atmospheres

TRBS 3151/TRGS 751:
Avoidance of fire, explosion and pressure hazards at filling stations and filling plants for filling land vehicles

TRGS 407:
Activities involving gases – Risk assessment

TRGS 507:
Surface treatment in rooms and containers

TRGS 509:
Storage of liquid and solid hazardous substances in stationary containers and filling and emptying points for mobile containers

TRGS 510:
Storage of hazardous substances in portable containers

TRGS 529:
Activities in the production of biogas

TRGS 723:
Hazardous explosive mixtures – Measures of constructive explosion protection which limit the effects of an explosion to a harmless level

TRGS 724:
Hazardous explosive mixtures – Measures of constructive explosion protection, which limit the effects of an explosion to a harmless level

TRGS 725:
Hazardous explosive atmospheres – Measuring, control and regulating devices within the scope of explosion protection measures

TRGS 727:
Avoidance of ignition hazards due to electrostatic charges

VDI 2263:
Dust fires and dust explosions; hazards, assessment, protective measures

VDI 2263 sheet 1:
Dust fires and dust explosions; hazards, assessment, protective measures; test methods for determining safety-related parameters of dusts

VDI 2263 sheet 2:
Dust fires and dust explosions; hazards, assessment, protective measures; inerting

VDI 2263 Sheet 3:
Dust fires and dust explosions; hazards, assessment, protective measures; explosion pressure shock resistant containers and apparatus; calculation, construction and testing

VDI 2263 sheet 4:
Dust fires and dust explosions; hazards, assessment, protective measures; suppression of dust explosions

VDI 2263 sheet 5:
Dust fires and dust explosions; hazards, assessment, protective measures; explosion protection in fluidized bed plants

VDI 2263 sheet 5.1:
Dust fires and dust explosions; hazards, assessment, protective measures; explosion protection in fluidized bed plants; instructions and design examples for manufacturers and operators

VDI 2263 sheet 6:
Dust fires and dust explosions; hazards, assessment, protective measures; fire and explosion protection at dust extraction plants

VDI 2263 sheet 6.1:
Dust fires and dust explosions; hazards, assessment, protective measures; fire and explosion protection on dust extraction systems; examples

VDI 2263 sheet 7:
Dust fires and dust explosions; hazards, assessment, protective measures; fire and explosion protection at spray drying plants

VDI 2263 sheet 7.1:
Dust fires and dust explosions; hazards, assessment, protective measures; fire and explosion protection at spray drying plants; examples

VDI 2263 sheet 8:
Dust fires and dust explosions; hazards, assessment, protective measures; fire and explosion protection on elevators

VDI 2263 sheet 8.1:
Dust fires and dust explosions; hazards, assessment, protective measures; fire and explosion protection on elevators; examples

VDI 2263 sheet 8.2:
Dust fires and dust explosions; hazards, assessment, protective measures; explosion suppression and combination of constructive protective measures on elevators

VDI 2263 sheet 9:
Dust fires and dust explosions; hazards, assessment, protective measures; determination of the dust behavior of bulk materials

VDI 3673 sheet 1:
Pressure relief of dust explosions

DIN EN 1127-1:
Explosive atmospheres, explosion protection,
Part 1: Basic principles and methodology

DIN EN 1127-2:
Explosive atmospheres, explosion protection,
Part 2: Basic principles and methodology in mines

DIN EN 1755:
Industrial trucks – Safety requirements and verification – Additional requirements for use in potentially explosive atmospheres

DIN EN 14491:
Protective systems for the pressure relief of dust explosions

DIN EN 14986:
Design of fans for use in potentially explosive atmospheres Avoidance of ignition hazards due to electrostatic charges