Many of the powders processed in food, pharmaceutical, nutraceutical, and chemical manufacturing are combustible. Flour, sugar, starch, milk powder, pharmaceutical excipients, and a wide range of fine chemical intermediates can form explosive dust clouds under the right conditions. A dust explosion is not primarily a function of how inherently flammable a material is — it is a function of whether five conditions exist simultaneously.
Russell Finex Ultrasonic Mesh Screens
The dust explosion pentagon describes those conditions: combustible dust (the fuel), an ignition source, oxygen, dispersion of the dust in sufficient concentration, and confinement. Remove any one of the five, and the explosion cannot occur. Processing equipment — mills, mixers, blenders, screeners, conveyors — operates in environments where all five conditions can be present at once. Milling in particular generates heat through mechanical action, creates fine particle size distributions, and operates in enclosed chambers where dust concentrations can reach explosive levels rapidly.
This is why the design and certification of powder processing equipment for use in hazardous areas is a distinct discipline, governed by internationally recognised standards. In New Zealand and Australia, that framework is IECEx, underpinned by AS/NZS 60079. In the European Union and for equipment sold into EU markets, it is ATEX.
Dinnissen Sampling Systems – ATEX Certified
Hazardous Area Classification: Zones 20, 21, and 22
The first step in managing explosive atmosphere risk is classifying the hazardous areas within a facility. For dust environments, both ATEX (Directive 2014/34/EU) and the IECEx scheme use a zone classification system that defines the likelihood and duration of an explosive atmosphere being present:
- Zone 20 — an explosive dust-air mixture is present continuously, for long periods, or frequently during normal operation. Typical examples: the interior of mills, mixers, blenders, conveyors, and storage vessels where powder is present at all times.
- Zone 21 — an explosive atmosphere in the form of a cloud of flammable dust in air is likely to occur occasionally during normal operation. Typical examples: areas adjacent to filling points, dust extraction outlets, and equipment that is opened regularly during operation.
- Zone 22 — an explosive dust-air mixture is not likely to occur in normal operation and, if it does occur, will persist for only a short period. Typical examples: the surrounding area of Zone 21 locations.
Zone classification determines the category of equipment that can be legally installed in that area. Equipment must be selected to match or exceed the zone — Zone 20 is the most demanding and requires the highest category of protection.
Hanningfield Uni Mill – ATEX Certified
ATEX and IECEx: Standards and NZ/AU Compliance
ATEX is the European Union’s regulatory framework for equipment intended for use in potentially explosive atmospheres, established under Directive 2014/34/EU. It covers both the design and manufacturing of equipment (ATEX Equipment Directive) and the minimum health and safety requirements for workers (ATEX Workplace Directive, 1999/92/EC). ATEX certification is mandatory for any equipment sold or installed in hazardous area locations within the EU.
IECEx is the International Electrotechnical Commission’s international certification scheme for equipment used in explosive atmospheres. In New Zealand and Australia, IECEx certification is the accepted framework for compliance, with the relevant standard series being AS/NZS 60079. IECEx and ATEX use the same underlying technical standards (IEC 60079 series) and the same zone classification system, making them closely aligned. In practice, a piece of equipment carrying both IECEx certification and ATEX certification can be specified for hazardous areas in both markets.
For New Zealand manufacturers exporting to the European Union, ATEX certification on installed equipment is a market access requirement. Specifying ATEX-certified equipment at the point of procurement removes a compliance barrier in export-oriented production.
Dinnissen Vacuum Coating System
Equipment Categories and Ignition Protection
ATEX and IECEx classify equipment by the level of protection it provides, matched to the zone in which it will operate:
- Category 1 / Equipment Protection Level (EPL) Da — for Zone 20. Required to maintain protection even in the event of two independent faults. Highest level of protection.
- Category 2 / EPL Db — for Zone 21. Required to maintain protection even in the event of a fault.
- Category 3 / EPL Dc — for Zone 22. Required to maintain protection under normal operation.
The design measures used to achieve these protection levels are defined as ignition protection types under the IEC 60079 standard series. For powder processing equipment, the most relevant protection types include:
- Ex t (dust ignition protection by enclosure) — prevents dust ingress and controls surface temperature; the primary protection type for electrically driven equipment in dust zones.
- Ex e (increased safety) — construction measures that reduce the probability of sparking or excessive temperatures, typically used for terminal boxes, motors, and junction boxes.
- Ex d (flameproof enclosure) — an enclosure that can withstand an internal explosion and prevent flame propagation to the surrounding atmosphere.
Beyond electrical protection, mechanical ignition risk must also be managed. In powder processing, critical measures include elimination of metal-to-metal contact in mills, temperature monitoring of bearings and drive components, static earthing and bonding to prevent electrostatic discharge, and nitrogen inerting where the process requires continuous Zone 20 protection.
Planning a processing or packaging project?
Speak with Advanced Packaging Systems about equipment selection, line integration, and local support in New Zealand.
- Local technical and commercial support in New Zealand.
- Obligation-free advice on equipment and line fit.
- Useful next steps, even if your project is still early-stage.
Partner Equipment with ATEX and IECEx Certification
APS represents a number of international manufacturers whose powder processing equipment carries formal ATEX certification, making it suitable for specification in hazardous area applications.
Dinnissen Process Technology
Dinnissen designs and supplies a range of powder processing equipment with ATEX certification for the food, feed, and chemical industries. The Pegasus® Batch Mixer carries ATEX Zone 20 internal certification, making it suitable for blending products with explosive dust characteristics. Dinnissen’s sampling systems are ATEX certified for internal zones 20, 21, and 22, and external zones 21 and 22. The Dinnissen centrifugal sifter range — including units up to 30-tonne throughput capacity — carries ATEX Zone 20 internal type approval for processing explosive substances.
Hanningfield
Hanningfield holds ATEX/Ex-Proof accreditation and self-certifies its Uni-Mill conical mill and Kwik-Sift centrifugal sifter for use in Zone 0/20. The Uni-Mill’s ATEX configuration incorporates a range of protective design features: temperature probes for continuous monitoring of mill and material temperature, nitrogen purging capability, HEPA-filtered dust containment, a no metal-to-metal contact drive design to eliminate spark risk, ATEX-rated motors and control panels, and earthing clamps to prevent electrostatic build-up. Hanningfield’s ATEX-certified milling equipment is used in pharmaceutical, nutraceutical, food, and nuclear applications globally.
Russell Finex
Russell Finex produces ATEX and IECEx certified vibratory sieves and separators, including the Russell Compact Sieve® and Finex Separator™. Russell Finex sieving equipment is certified for Zone 0/20 (internal to the sieve) and zones 21, 22, 1, and 2 (external). The Vibrasonic® deblinding system is designed for use in Zone 0/20, with a fully enclosed cable and transducer and a flameproof cover. All Russell Finex equipment in hazardous area configurations incorporates grounded components and EX motors with dust-tight or flameproof enclosures to prevent static build-up and ignition.
Dinnissen Hammer Mill with Feed system
Specifying Compliant Equipment for Your Application
Selecting the correct equipment for a hazardous area application requires an assessment of the zone classification, the appropriate equipment protection level, and the specific ignition risks associated with the process and material. It is not sufficient to specify generally suitable equipment — compliance requires documented zone classification and matching equipment certification.
Advanced Packaging Systems works with customers at the specification stage for powder processing applications in New Zealand. Contact us to discuss hazardous area classification for your process, or to obtain technical data on ATEX and IECEx certification for specific partner equipment.
