Accessories for ATEX filter units — April 2026

Discharge and Safety Systems for ATEX filter units

Depureco's central filter units — DV AIR, FILTER HOPPER, CVS Z22, HF Z22 — ship without a discharge system and without safety components. The components that live behind the catalogue phrase “see dedicated section” are gathered here, with guidance on selection, ATEX variant and zone classification.

See discharge systems See safety systems
Rotary valve, vent panel and flameless vent from Depureco's discharge and safety catalogue
Summary

Discharge system = how the collected dust leaves the filter unit (intermittent batch, continuous operation, or big-bag). Safety system = the five ATEX-certified components that prevent an internal dust explosion from spreading to the rest of the building (vent panel, non-return valve, flameless vent, CO2 extinguishing). Both categories are sold separately from the filter unit — because the component choice depends on your process, your zone classification and your risk assessment.

Why sold separately from the filter unit?

All of Depureco's central filter units — DV AIR, DV AIR WB, FILTERING PRE-SEPARATOR WB, FILTER HOPPER, HF / HF HD Z22 and the CVS centrals — ship without discharge and safety components. Datasheets consistently refer to the phrase “DISCHARGE SYSTEMS — see dedicated section” and “SAFETY SYSTEMS — see dedicated section”. The reason is that the component choice is application-dependent: two installations with the same filter can have very different requirements for discharge method, ATEX variant and safety instrumentation.

Specifically, the choice depends on:

  • Operating pattern: is the filter emptied in batch (manual or intermittent), or does it need to run continuously in production?
  • Zone classification: does the discharge component itself sit in or near an ATEX-classified zone? That determines whether you need the standard or ATEX variant.
  • Risk assessment: which ATEX safety barriers are required per EN 14491 (vent discharge), EN 14460 (pressure-resistant construction) and EN 16447 (isolation via non-return valve)?
  • Dust character: is the dust conductive (IIIC) or non-conductive (IIIB)? Is it self-heating? Reactive?

Therefore this page is not a catalogue overview alone, but a selection guide: for each component there is a short explanation of when it makes sense — and when it does not.

Discharge Systems

Depureco's discharge catalogue follows two main operating patterns: intermittent (batch emptying, manual or counterbalance-driven) and continuous (continuous outflow via rotary valve or electropneumatic damper). In addition there is a level sensor used to trigger continuous discharge on and off. Big-bag collection is not part of this page — the big-bag frame logically belongs with the pre-separators and is found on the FILTER HOPPER pages.

Intermittent discharge — batch emptying

Used when the filter unit is emptied at stopped operation or at regular intervals. Simple mechanics, no electropneumatics, no ATEX variant in the catalogue — because the component sits at the filter outlet and has no spark or heat sources in normal operation. The choice is between counterbalanced flap (opens under dust weight) and manual butterfly valve (handwheel, operator controlled).

Counterbalanced flap, diameter 150 mm (P12390)

Counterbalanced flap discharge — 150 mm

P12390 150 mm Non-ATEX

Counterweight flap that opens when dust weight overcomes spring tension. Suitable for FILTER HOPPER 450 (150 mm outlet) and DV AIR 800 (150 mm outlet in certain configurations). No external power, no pneumatics.

Counterbalanced flap, diameter 250 mm (P12391)

Counterbalanced flap discharge — 250 mm

P12391 250 mm Non-ATEX

Same mechanism in larger format for FILTER HOPPER 570/800 and FILTERING PRE-SEPARATOR 570/800 WB.

Manual butterfly valve, diameter 150 mm (P12392)

Manual butterfly valve — 150 mm

P12392 150 mm Non-ATEX

Handwheel-operated butterfly valve for 150 mm outlet. Used when emptying happens at a defined time under operator control — for example at shift change or planned downtime.

Manual butterfly valve, diameter 250 mm (P12393)

Manual butterfly valve — 250 mm

P12393 250 mm Non-ATEX

250 mm variant for larger filter units. Same handwheel type.

Continuous discharge — uninterrupted operation

Used when the filter must run without interruption and dust flows continuously to a next-stage collector (big-bag, container, conveyor). All three types come in both standard and ATEX variants — the ATEX variant must be used when the component sits in or near an ATEX-classified zone.

Double guillotine damper, diameter 300 mm (P13245)

Double exhaust, electropneumatic guillotine dampers — 300 mm

P13245 300 mm Non-ATEX

Airlock principle: two guillotine dampers that open and close in sequence so there is never direct flow-through in the filter. Electropneumatic control via compressed air. Standard variant for non-classified installation.

Double guillotine damper, ATEX variant (P12398/EX)

Double exhaust, electropneumatic guillotine dampers — 300 mm (ATEX)

P12398/EX 300 mm ATEX

Same mechanism as P13245, but ATEX-certified for installation in or near a classified zone. Choose this when the discharge component sits in Zone 22 or higher.

Rotary valve, diameter 250 mm (P12736)

Rotary valve — 250 mm

P12736 250 mm Non-ATEX

Classic star-shaped rotor that transports dust through a fixed airlock. Constant extraction without pneumatic cycling. Electric drive, speed adjustable.

Rotary valve, ATEX variant (P12736/EX)

Rotary valve — 250 mm (ATEX)

P12736/EX 250 mm ATEX

ATEX-certified rotary valve. Certification covers grounding, spark-free construction and surface temperature. Choose this when discharge happens in a classified zone.

Double butterfly damper, diameter 150 mm (P12394)

Double discharge, electropneumatic butterfly dampers — 150 mm

P12394 150 mm Non-ATEX

Two butterfly dampers in sequence — airlock principle similar to guillotine dampers, but more compact for 150 mm outlets. Electropneumatic control.

Double butterfly damper, ATEX variant, diameter 150 mm (P12396)

Double discharge, electropneumatic butterfly dampers — 150 mm (ATEX)

P12396 150 mm ATEX

ATEX variant of P12394. Same airlock mechanics, zone-certified.

Double butterfly damper, diameter 250 mm (P12395)

Double discharge, electropneumatic butterfly dampers — 250 mm

P12395 250 mm Non-ATEX

250 mm variant of the butterfly-damper airlock. Used with FILTER HOPPER 570/800 and FILTERING PRE-SEPARATOR 570/800 WB, which have 250 mm outlets.

Double butterfly damper, ATEX variant, diameter 250 mm (P12397)

Double discharge, electropneumatic butterfly dampers — 250 mm (ATEX)

P12397 250 mm ATEX

ATEX variant of P12395. Typical choice for FILTER HOPPER in Zone 22 areas.

Level activation — discharge system activation

Sits on the filter hopper or bin and provides an on/off signal when the dust level reaches a defined height. The signal is used to start or stop continuous discharge automatically — an airlock running “blind” does more work than necessary and wears unnecessarily.

Rotary level sensor (P10166)

Rotary level sensor

P10166

Mechanical level detector with a rotor blade that stalls when dust reaches sensor height. Simple, robust, no electronics in the dust zone. Typical choice for continuous installations with rotary valve or double damper.

Safety Systems

Detect — Isolate — Protect

The ATEX Directive requires industrial users to draft an Explosion Protection Document that shows how the risk is managed. The five safety components in this catalogue are not extras — they are the concrete solutions to the ATEX principle detect, isolate, protect.

1. Detect

Register the initiating event. Level sensor, pressure rise, temperature — all signals that in the Depureco line tie into standard control systems and, for active protection, trigger the CO2 extinguishing system.

2. Isolate

Stop the flame front from progressing. Non-return valves (P12774-ST1, P12774) close against reverse pressure and prevent an internal explosion from propagating to upstream equipment. Certified per EN 16447.

3. Protect

Vent the pressure in a controlled manner. Vent panel (P12773) to open air, flameless vent (P12775) indoors, and CO2 system (P12777) as active extinguishing. The construction must match the documented reduced explosion pressure Pred.

The five components below are Depureco's catalogue series. Which combination you need depends on a concrete risk assessment per EN 14491, EN 14460 and EN 15089 — plus building geometry and dust type (IIIB vs IIIC).

Vent panel G5, 200 mm (P12773)

Vent panel G5 — 200 mm

P12773 200 mm ATEX / EN 14491

Open pressure relief. At internal overpressure the panel bursts and releases the pressure wave and flame to open air. Requires that the filter stands at an outer wall or rooftop, and that the discharge zone is clear of personnel and equipment. Cheaper and more reliable than flameless vent, but limited by building geometry.

Non-return valve for IIIB, EN 16447 (P12774-ST1)

Non-return valve, non-metallic powders — 100 mm

P12774-ST1 100 mm counterflange ATEX EN 16447

EN 16447 certified passive non-return valve. Closes when buoyant pressure from an explosion moves backwards toward upstream equipment. Variant for non-conductive dust (IIIB level) — milk, pharma powder, plastic granulate, wood.

Non-return valve for IIIC, ATEX 1/2D (P12774)

Non-return valve, IIIC explosive powders — 100 mm

P12774 100 mm counterflange ATEX 1/2D Ex h III T180°C Da/Db ST1/ST2

Heavier variant for conductive dust (IIIC) — aluminium, titanium, carbon fibre, fine metal shavings. Covers the entire IIIC group and the highest ST1/ST2 explosion classes, with a maximum surface temperature of 180°C.

Flameless vent (P12775)

Flameless valve vent

P12775 ATEX

Flame-free pressure relief for indoor use. Contains a mesh filter that cools the exiting gas below the ignition temperature before releasing it to the room — i.e. the pressure is vented but no flame escapes. More expensive than an open vent panel, but necessary when building geometry or space constraints rule out external venting.

CO2 extinguishing system (P12777)

CO2 extinguishing system

P12777 ATEX / active extinguishing

Active sensor-triggered extinguishing. CO2 is injected into the filter chamber when a spark or incipient thermal event is detected by a sensor. Used in installations where passive venting (vent panel / flameless vent) alone is insufficient — typically with highly reactive dust types or as a supplementary barrier in multi-layer protection.

Thomas from Particulair — technical advisory on accessories and safety systems

Not sure what to choose?

The combination of discharge and safety systems depends on the filter unit, dust type, operating pattern and your risk assessment. We help you walk through the configuration, also if you already have an existing Depureco installation and need to supplement or upgrade. Call or write — we reply within one business day.

Contact advisory See ATEX vacuums

Frequently asked questions

Why isn't the discharge system included with the filter unit?
Because the choice depends on your process. A FILTER HOPPER or DV AIR can be combined with batch emptying (counterbalanced flap, manual butterfly valve), continuous operation (rotary valve, double discharge, guillotine damper) or big-bag collection. Diameters are 150, 250 or 300 mm depending on the filter outlet. Depureco therefore ships the filter unit so it can be paired with exactly the discharge pattern you need — standard or ATEX-certified variant.
Do I need the ATEX variant or the standard variant of the discharge system?
It depends on the zone classification at the physical location of the component. If the discharge system sits in or near an ATEX-classified zone (Zone 20, 21 or 22), the component must be ATEX-certified to at least the corresponding category. Most continuous-discharge components from Depureco come in both standard (P12736, P13245, P12394, P12395) and ATEX variants (P12736/EX, P12398/EX, P12396, P12397). Choose standard for an unclassified area, ATEX for a classified zone.
When does my installation require a vent panel or flameless vent?
The ATEX Directive 2014/34/EU requires that explosion risk is assessed via a risk assessment (typically EN 14491 for dust explosion venting). If the assessment shows that an internal dust explosion can occur and the filter itself is not constructed to withstand the reduced explosion pressure (EN 14460), the pressure must be vented — either via an open vent panel (P12773) to an outdoor or safe discharge zone, or via a flameless vent (P12775) when venting must occur indoors. Flameless vent is more expensive but necessary when space constraints or building geometry prevent traditional pressure venting to open air.
Can I buy Depureco's accessories separately from the filter unit itself?
Yes. All discharge and safety components are sold as standalone catalogue items with their own codes (P-numbers). They can be ordered together with a new filter unit or retrofitted to an existing installation. It is important that the diameter and flange format match the filter outlet: DV AIR 800 and FILTER HOPPER 450 have 150 mm discharge; FILTER HOPPER 570 and 800 have 250 mm; DV AIR 1100 has 150 mm. Contact us if you are in doubt about the configuration.
What's the difference between a non-return valve for IIIB and for IIIC dust?
IIIB is non-conductive dust (e.g. milk powder, flour, plastic granulate). IIIC is conductive dust (e.g. aluminium, titanium, carbon fibre, fine metal shavings). Depureco's non-return valve P12774-ST1 is EN 16447 certified for non-metallic powders (IIIB level). P12774 is ATEX-certified 1/2D Ex h III T180°C Da/Db ST1/ST2 for explosive IIIC powders — i.e. the full conductive-dust group including metals. Choose based on what the actual inventory of collected substances contains.
Can we install discharge and safety systems ourselves, or does it require authorised installation?
Mechanical installation of discharge components (rotary valve, butterfly damper, flap) can be carried out by the company's own technical personnel, provided they follow EN 14460 and the manufacturer's instructions for flange connection, grounding and torque. Safety systems with ATEX certification (non-return valves, flameless vent, CO2 extinguishing) should normally be installed and commissioned by an authorised specialist, because the installation documentation becomes part of the overall plant risk assessment. A common compromise is that we deliver the components and hand them over to a qualified installer, who closes out with a system test and a signed installation report.
How often do discharge and safety systems need servicing?
The ATEX Directive and manufacturer documentation set minimum intervals. Rotary valve and butterfly damper typically require visual inspection every 3 months and annual function testing. Vent panel should be inspected at least once a year — check for hairline cracks and that the burst pressure is intact. Flameless vent has a filter cartridge that must be replaced after an activation and is otherwise inspected annually. Non-return valves need annual function testing. The CO2 system has service intervals on pressure level and electronics typically every 6 months. We recommend a service agreement where all components are documented in the same log — audit requirements become much easier.
What is the rotary level sensor for, and do I need one?
The rotary level sensor (P10166) is a mechanical level detector that sits on the filter unit's hopper or bin and can start or stop a continuous discharge when the dust level reaches a defined height. It is relevant when the discharge is continuous (rotary valve, double discharge damper) — so control runs in step with collection without manual supervision. With purely intermittent emptying (counterbalanced flap, manual butterfly valve) it is not required.

Compatible filter units

The accessories on this page are compatible with Depureco's stationary filter units and central systems. Here is a short overview of the filter units the accessories typically pair with:

Pre-separators (FILTER HOPPER)

DV AIR filter units

Central systems (CVS and HF)

References

Directives and harmonised standards

  1. EU: ATEX Directive 2014/34/EU — Equipment and protective systems intended for use in potentially explosive atmospheres.
  2. EU: Directive 1999/92/EC (ATEX 137) — minimum requirements for the safety and health of workers at risk from explosive atmospheres.
  3. CEN: EN 14491:2012 — Dust explosion venting protective systems.
  4. CEN: EN 14460:2018 — Explosion resistant equipment.
  5. CEN: EN 16447:2014 — Explosion isolation flap valves.
  6. CEN: EN 15089:2009 — Explosion isolation systems.
  7. CEN: EN ISO 80079-36:2016 — Explosive atmospheres. Part 36: Non-electrical equipment. Basic method and requirements.
  8. CEN: EN 1127-1:2019 — Explosive atmospheres. Explosion prevention and protection. Part 1: Basic concepts and methodology.

Manufacturer documentation

  1. Depureco: ENG Price List 2026 v1.1, Centralized Vacuum Systems, page 162 (Discharge Systems) and page 163 (Safety Systems).
  2. Depureco: Don't Let Dust Threaten Your Production — ATEX Vacuum Catalogue 2026, Volpiano (TO), 2025.

Danish legislation

  1. Executive Order No. 590 of 26 June 2003 on the classification of explosive atmospheres (ATEX 137 in Denmark).
  2. The Danish Working Environment Authority: guideline C.0.9 on explosive atmospheres.