ATEX Zone 20/21 Compliant Valve: Doebritz high-accuracy powder dosing screw | Certified Explosion Safety

Precision Dosing & Explosion-Safe Material Handling

The Doebritz high-accuracy powder dosing screw is a heavy-duty rotary valve engineered for precise volumetric feeding and extreme durability in explosive atmospheres. Designed for continuous heavy industrial service, this airlock feeder integrates ATEX Zone 20/21 certified flameproof construction, CNC-machined rotor-to-housing clearances below 0.2 mm, and advanced shaft sealing to guarantee minimal air leakage and unmatched metering accuracy under high differential pressure. Built upon Doebritz’s world-class manufacturing infrastructure, this valve delivers reliable performance across pneumatic conveying, gravity discharge, and automated batching lines.

Why Plant Sourcing Chooses Doebritz High-Accuracy Powder Dosing Screw

• Ultra-Low Leakage Airtightness: The precision-ground rotor and housing achieve consistent clearances (0.1–0.2 mm), dramatically reducing air bypass and ensuring stable dense-phase or dilute-phase conveying with lower energy consumption.
• ATEX Zone 20/21 Certified Safety: Fully compliant with ATEX directives for explosive dust atmospheres. The flameproof enclosure, 16 bar pressure-rated housing, and anti-static rotor construction provide robust protection in high-risk zones.
• Heavy-Duty Wear Resistance: Available in SUS304, SUS316L, carbon steel with tungsten carbide coating, ceramic lining, or polymer cladding – tailored to handle highly abrasive powders like carbon black, lithium battery materials, and mineral fillers without premature wear.
• Quick-Clean Hygienic Design: The quick-release demountable structure enables rapid disassembly without special tools, facilitating manual cleaning, online CIP, or WIP cleaning – critical for food, pharmaceutical, and high-purity chemical applications.
• Precision Volumetric Dosing & Automation: Equipped with VFD and PLC-ready controls, the dosing screw enables accurate batch metering, recipe-based feeding, and fully automated material flow regulation. Flow rates are easily adjusted to match production demands.

Housing & Rotor Engineering for Demanding Applications

Constructed from heavy-wall cast iron or investment-cast stainless steel, the Doebritz high-accuracy powder dosing screw features an outboard bearing configuration that isolates the bearing housing from the material zone, preventing contamination and enabling high-temperature operation up to 120°C. The rotor geometry is optimized for low-shear, non-jamming flow, minimizing product degradation for friable materials. For sanitary lines, internal surfaces can be finished to Ra ≤ 0.4 μm mirror polish with crevice-free welds, meeting GMP and Class 10W/100K cleanroom standards.

The shaft sealing system combines lip seals with air purge to prevent dust migration into the bearing area. For abrasive applications, an optional lantern ring with purge air further extends seal life. All wetted parts are meticulously machined on Doebritz’s 5-axis CNC centers, ensuring consistent part interchangeability and long-term reliability.

Technical Specifications

Below are the standard parameters for the Doebritz high-accuracy powder dosing screw. Custom configurations are available for specific pressure, temperature, and material requirements.

Specification	Detail
Body Material	SUS304, SUS316L, Carbon Steel (with optional coatings)
Rotor Design	6-Vane / 8-Vane Open Rotor, Precision Ground
Clearance (Rotor to Housing)	0.1 – 0.2 mm
Pressure Rating	Up to 16 bar (ATEX flameproof version)
ATEX Certification	Zone 20, 21, 22 (Optional)
Flange Standards	HG20592, DIN, ANSI (DN50 to DN350)
Shaft Sealing	Lip Seal with Air Purge / Lantern Ring Option
Surface Finish (Internal)	Ra ≤ 0.4 μm (Mirror), Ra ≤ 0.8 μm, Ra ≤ 1.6 μm
Cleanability	Quick-Release Demount, CIP, WIP
Temperature Range	Ambient: -15°C to 60°C; Material: 0°C to 120°C
Cooling System	Optional Water Jacket
Motor & Control	VFD-Ready, PLC Automation, Explosion-Proof Motor

Heavy-Duty Application Scenarios

Explosive Dust Pneumatic Conveying (ATEX Zones 20/21)

Ideal for conveying combustible powders such as aluminum powder, fine carbon black, pharmaceutical actives, and food starch in closed-loop systems. The ATEX-certified construction ensures safety while the tight clearances maintain stable conveying pressure.

High-Pressure Dense Phase Feeding

The reinforced housing and precision rotor make this valve suitable for dense phase pneumatic conveying at pressures up to 1 bar, delivering consistent material flow to downstream mixers, reactors, or packaging machines. The variable frequency drive enables precise feed rate adjustment from low to high throughput.

Hygienic Batching in Food & Pharma

With quick-release disassembly and mirror-polished internals, the dosing screw supports CIP/SIP cleaning protocols and prevents cross-contamination during batch changes. Common applications include baby formula, instant beverage powders, vitamin premixes, and pharmaceutical granules.

High-Wear Mineral & Chemical Processing

For titanium dioxide, silicon powder, lithium battery cathode materials, and cement additives, the optional tungsten carbide or ceramic coating extends service life by 3–5 times compared to standard stainless steel, reducing maintenance downtime and total cost of ownership.

Doebritz Global OEM Assurance

As a premier heavy-equipment manufacturer, Doebritz combines in-house casting, precision machining, and ATEX-certified assembly to deliver valves that meet the strictest international standards. Every unit is tested for air leakage, volumetric efficiency, and pressure integrity before shipment. With a global supply chain, we offer custom flanges (DIN, ANSI, HG20592), tailored materials, and expedited lead times for both standard and bespoke configurations.

Backed by CE, TÜV, and Statement certifications, our valves are trusted by Fortune 500 companies in over 60 countries. From engineering support to after-sales spares, Doebritz provides a complete lifecycle partnership.

Frequently Asked Questions

What are the standard flange options for the Doebritz high-accuracy powder dosing screw?

We supply valves with DIN, ANSI, and HG20592 flanges in sizes ranging from DN50 to DN350. Custom drilling patterns are also available upon request.

Can this valve handle sticky or hygroscopic powders?

Yes. The polished internal surfaces and optional PTFE or polymer coatings reduce material adhesion. Additionally, the rotor’s vane design prevents packing and ensures smooth discharge.

Is the Doebritz dosing screw suitable for high-temperature processes?

The standard design supports material temperatures up to 120°C. For higher temperatures (up to 400°C), we offer specialized high-temperature materials and cooling jackets.

How does the ATEX certification affect the valve’s construction?

ATEX-compliant units feature flameproof enclosures, anti-static rotor grounding, and maximum gap control to prevent ignition. The housing is pressure-rated to 16 bar to withstand internal deflagrations.

What is the typical lead time for a customized Doebritz dosing screw?

Standard models can ship within 4–6 weeks. Custom-engineered solutions with specialized materials or coatings typically require 8–12 weeks, depending on complexity and testing requirements.