Direct Discharge Sifter, Doebritz Screening Valve, High-Capacity / ATEX Certified / Dust-Tight

Product Summary

Engineered for continuous, high-capacity separation of oversize particles and foreign matter, the Doebritz Direct Discharge Sifter integrates screening and pneumatic conveying into a single, dust-tight unit. Capable of processing up to 120 m³/h of powder, granular materials, or friable pellets, this sifter features a low-profile, direct discharge housing that eliminates intermediate hoppers and reduces headroom requirements. The ATEX-certified construction (Zone 22 internal / Zone 22 external) ensures safe operation in explosive dust atmospheres. With a rotational speed range of 200–1500 RPM and interchangeable screen baskets from 0.5 mm to 12.7 mm, the Doebritz Direct Discharge Sifter delivers residual fines below 0.5% for critical airlock feeding applications.

Why Source Doebritz Direct Discharge Sifter

• Ultra-Low Air Leakage & Pressure Drop: Precision-machined rotor tips with ≤0.15 mm radial clearance maintain <0.2 m³/h air leakage at 0.5 bar differential pressure, maximizing pneumatic conveying efficiency.
• Heavy-Duty CNG Machined Components: All critical interfaces (rotor shaft, end plates, flange faces) are CNC-turned from GGG-40.3 ductile iron or 304/316L stainless steel for true roundness and zero runout.
• Explosion-Protected & Global Certified: Standard ATEX II 2D c T130°C (Zone 21) and optional IECEx, NEC 500 (Class II, Div 1) configurations available. Anti-static PTFE seals prevent ignition source propagation.
• 30-Minute Screen Changeover: Quick-release clamp rings and tool-free access door allow screen basket replacement without removing the sifter from the line. >95% uptime design for continuous process lines.
• OEM Supply Chain & Customization: Doebritz offers semi-finished castings with ASME B16.5 or EN 1092-1 flanges, custom inlet/outlet offsets, and FDA-compliant polished interiors for food & pharmaceutical grades.

Housing & Rotor Engineering

The Doebritz Direct Discharge Sifter housing is manufactured from sand-cast EN-GJL-250 grey iron (or investment-cast CF8M stainless steel for sanitary applications), featuring integral stiffening ribs that dampen vibration and prevent fatigue cracking under full vacuum service. The internal rotor assembly utilizes a cantilevered shaft with outboard bearings, completely isolated from the product zone via four-lip PTFE/graphite air purge seals. Rotor paddles are dynamically balanced to G-6.3 precision and can be equipped with replaceable polyurethane tips or ceramic-coated edges for abrasive materials like silica sand or carbon black. The screen basket features ribbed stainless steel perforated plate (2–12 mm) or woven mesh down to 0.5 mm, reinforced by a radial cross-brace to prevent collapse under differential pressure. All interior welds are ground continuous (Ra < 1.6 μm) to eliminate material hang-up.

Technical Specifications

Performance data validated on Doebritz in-house test loop with air flow measurement and laser particle analysis. Custom configurations available for extreme temperatures (-20°C to +280°C) and corrosive media. Contact Doebritz engineering for application-specific sizing.

Specification	Detail
Body Material	EN-GJL-250 Grey Iron / CF8M (316L) Stainless Steel
Rotor Design	8-Vane Open Rotor with Replaceable PU/Ceramic Tips
Screening Area	0.25 m² to 1.8 m² (4 standard frame sizes)
Screen Aperture	0.5 mm (woven mesh) – 12.7 mm (perforated plate)
Max Rotational Speed	1500 RPM (balanced to G-6.3)
Air Leakage (0.5 bar delta P)	<0.2 m³/h (new seals, dry air)
Temperature Range	-20°C to +150°C (standard) / +280°C (HT upgrade)
ATEX Certification	II 2D c T130°C (Zone 21) / optional II 1/2 D for Zone 20
Flange Standards	ASME B16.5 Class 150 / EN 1092-1 PN10 / Custom

Heavy-Duty Application Scenarios

Pneumatic Conveying Systems (Dilute & Dense Phase)

Installed directly below a filter receiver or cyclone discharge, the Doebritz Direct Discharge Sifter continuously removes agglomerates and tramp metal while feeding into a rotary airlock valve. Product-to-air ratio up to 15:1 without bridging or blinding.

Silo Discharging with Lump Breaking

Mounted on square/round silo outlets (400×400 mm to 800×800 mm), the sifter handles 100+ tons/hour of pellets or flakes, protecting downstream mills and mixers. Optional integrated deagglomerator rotor crushes soft lumps before screening.

Dust Filter Collectors & Baghouse Discharge

For reclaiming valuable product from dust collection hoppers, the Doebritz unit operates under -50 to +50 mbar pressure, ensuring 99.9% product recovery while preventing dust re-entrainment through the airlock seal.

Chemical & Mineral Processing

ATEX-certified configuration with earthing strap, stainless steel housing, and anti-friction PTFE lining is widely used for PVC powder, carbon black, ammonium nitrate prills, and hydrated lime.

Frequently Asked Questions

Q1: What is the maximum permissible particle size for the Doebritz Direct Discharge Sifter?

A: The maximum feed particle size depends on screen aperture and rotor speed. For free-flowing materials, particles up to 2/3 of the screen aperture (typically ≤8 mm) can be processed without risk of jamming. Larger friable lumps up to 50 mm require our optional breaker rotor assembly.

Q2: Can Doebritz provide non-standard inlet/outlet flanges and special materials?

A: Yes. As an OEM supplier, Doebritz offers any flange drilling per ASME, DIN, JIS, or custom bolt patterns. Housing materials include 316L stainless steel, Hastelloy C-22, duplex 2205, and aluminum for high-purity applications. Minimum order quantity is 4 units for non-standard castings.

Q3: What ATEX certifications are available, and what is the lead time for an explosion-proof model?

A: Standard ATEX II 2D c T130°C (Zone 21/22) — 4 weeks ARO. For Zone 0/20 (gas/dust) with full Ex t IIIC T125°C Da, including certified temperature probe and intrinsically safe speed monitor — 8 weeks ARO. Doebritz provides a complete DOC (Declaration of Conformity) and certified engineering dossier.

Q4: How do I clean the sifter for product changeovers, and is CIP (Clean-in-Place) available?

A: The standard unit features quick-open clamps and swing-away housing for manual washdown. For food/pharma applications, Doebritz offers a CIP-ready design with spray nozzles, sloped surfaces (≥3°), and a purgeable rotor seal. CIP validation protocol (Rinse, Swab, ATP test) can be provided.

Q5: What is the typical replacement interval for seals and screen baskets under heavy-duty use?

A: With abrasive minerals (e.g., silica sand, 50 tons/week), rotor tip seals last 1,500–2,000 hours, screen baskets 3,000–4,000 hours. For gentle materials (plastic pellets, grains), seals exceed 8,000 hours and screens 12,000+ hours. Doebritz stocks all wear parts — air shipment within 24 hours for critical breakdowns.