Big bag unloading station for hazardous substances with extraction: ATEX certified
Direct answer: A big bag unloading station for hazardous substances with integrated extraction and ATEX certification combines three critical functions: safe emptying of a big bag (FIBC) without operator exposure to the hazardous material (containment), extraction of dust emissions via a HEPA H14 or ULPA filter (dust control), and certified explosion safety per ATEX Directive 2014/34/EU (Zone 20/21). This type of unloading station is mandatory for toxic, combustible or OEB 3+ powders in the pharmaceutical, chemical and battery industries.
When is an ATEX-certified unloading station with extraction required?
A standard big bag unloading station is sufficient for non-combustible, non-toxic powders in a non-classified environment. As soon as the product or environment meets one of the following criteria, a certified unloading station with extraction is required:
- Combustible powder (Kst >0): The unloading station is located in Zone 20 (interior) or Zone 21 (surroundings). All electrical components must be ATEX-certified for the designated zone.
- Toxic powder (OEB ≥ 3): The operator exposure limit is <100 µg/m³. Extraction with a HEPA filter on the unloading station alone is insufficient — a closed coupling (split-butterfly valve or equivalent) is required.
- Combination of combustible + toxic: The most complex situation. Requires a system that meets both ATEX and containment requirements — technically achievable but must be specifically engineered.
Key components of an ATEX-certified unloading station with extraction
1. Construction and frame
The unloading station frame is constructed in 304 or 316L stainless steel — non-sparking, corrosion-resistant. Lifting construction per NEN-EN 13155 for safe lifting of the big bag (max weight incl. load). Stable four-point design with adjustable height for connection to various container heights.
2. Integrated extraction with ATEX filter
The extraction unit is integrated into the unloading station — an external fan connected to an integrated filter housing. The fan is ATEX-certified (minimum category 2D for Zone 21 around the unloading station). The filter housing contains a HEPA H14 filter with a bag-in/bag-out (BIBO) exchange mechanism for safe filter changes without exposure. Differential pressure monitoring provides an alarm when the filter becomes clogged.
3. Closed coupling
The coupling of the big bag outlet to the unloading station is the most critical emission point. Depending on the product's OEB level:
- OEB 1–2: Mechanical clamp-ring seal with EPDM sealing rubber. Simple and effective for non-toxic powders.
- OEB 3: Inflatable seal — an inflatable rubber sleeve that hermetically seals the big bag outlet.
- OEB 4–5: Split-butterfly valve (SBV) — active/passive principle that preserves containment during connection and disconnection. SMEPAC-tested.
4. Grounding and bonding
The entire unloading station is equipped with an integrated grounding system: grounding points on the frame, on the extraction unit and on the coupling. A clamp connection to the big bag grounding loop (type C FIBC) closes the grounding circuit. Grounding resistance <10 Ω, verifiable with an integrated grounding tester before starting each unloading operation.
ATEX unloading station: technical specifications
| Parameter | Standard version | OEB 4/5 version |
|---|---|---|
| ATEX zone | Zone 21 (2D) | Zone 20/21 (1D/2D) |
| Filter | HEPA H14 | ULPA U15 or double HEPA |
| Coupling | Inflatable seal | Split-butterfly valve (SBV) |
| Big bag type | Type C | Type C or D |
| Containment evidence | Filter test | SMEPAC test |
FAQ: ATEX big bag unloading station with extraction
Can an ATEX unloading station also be used for non-hazardous substances?
Yes. An ATEX-certified unloading station can also be used for non-hazardous powders — the certification is a minimum requirement, not a restriction. The advantage is that the installation remains flexible when the product portfolio changes or when new products with higher ATEX requirements are introduced.
How often does the HEPA filter need to be replaced?
Replacement is based on differential pressure monitoring: when the pressure drop exceeds the set alarm threshold. As a rule of thumb for intensive use (multiple big bags per day): every 3–6 months. The filter replacement procedure via the BIBO system can be carried out without exposure to the filtered material.
Does Hecht Technology also supply the complete unloading station including IQ/OQ documentation?
Yes. Hecht Technology supplies big bag unloading stations as a complete, FAT-tested unit including CE marking, ATEX certificates for all electrical components, grounding report, maintenance manual and, optionally, an IQ/OQ validation dossier for GMP applications.
Need an ATEX-certified unloading station for your hazardous substance?
Hecht Technology designs and supplies custom big bag unloading stations for hazardous and toxic powders — ATEX-certified, GMP-compliant and SMEPAC-tested. Request a technical consultation.
Author: Hecht Technology B.V. | Technical editorial | Updated: June 2026
Our products for hazardous substances
- Big bag filling station with HS column
- LAS-EC "Easy Connect" big bag connection system
- AAS big bag connection system
- Big bag racks and modular frames
Also read
- What is ATEX and why is it important?
- What are the benefits of an ATEX system
- How is an ATEX system maintained
- HECHT containment solutions