Blow-Through Rotary Valve, Doebritz Airlock, High-Pressure Conveying / ATEX Certified

Product Summary

Doebritz presents the heavy-duty Blow-Through Rotary Valve series – engineered for continuous, high-pressure pneumatic conveying systems. This airlock feeder handles up to 80 m³/h of powder, granular, or flaky materials while maintaining a differential pressure of 1.5 bar. Built with CNC-machined rotors and ATEX-certified explosion-proof housing, the Doebritz blow-through design ensures material is fluidized and accelerated directly in the valve body, eliminating separate blow pots. Ideal for cement, chemical, and food-grade applications requiring zero contamination and minimal degradation.

Why Source Doebritz Blow-Through Valves

• Unmatched Air Sealing: Achieve leakage rates as low as 0.1 Nm³/h at 1 bar differential, verified by helium leak tests – saving pneumatic conveying energy costs.
• CNC Precision Rotors: Each 8, 10, or 12-vane rotor is machined from single billet stainless steel or cast iron with tip clearance ≤0.10mm, ensuring consistent volumetric efficiency over 20,000+ operating hours.
• ATEX & Global Certifications: Full ATEX Zone 22 internal, Zone 2 external; available with IECEx, GOST-R, and NFPA compliance for dust explosion risks.
• OEM-Ready Customization: Tailored inlet/outlet flanges (ANSI, DIN, JIS), shaft materials, hardening coatings (Stellite, Tungsten Carbide), and purge connections for sticky or hygroscopic materials.
• 24/7 Heavy-Duty Support: Doebritz provides global aftermarket parts, quick-ship rotors, and field inspection services – reducing your plant downtime.

Housing & Rotor Engineering

The Doebritz Blow-Through Rotary Valve features a one-piece ductile cast iron (GGG40) or stainless steel 316L housing with integrated material inlet and outlet flanges – no welded seams that create stress risers. The blow-through configuration uses a tangential outlet port that aligns with the rotor pockets, allowing compressed air to fluidize and push material downstream. Outboard bearings with triple labyrinth seals isolate the conveying line from bearing housings, preventing contamination and bearing failure. For abrasive materials, optional hard-faced rotor tips (63 HRC) and replaceable wear liners extend service life by 3x. Every unit is dynamically balanced to G6.3 grade for vibration-free operation at speeds up to 60 RPM.

Technical Specifications

All Doebritz blow-through valves are pressure-tested per EN 12266-1 and dimensioned according to ISO 5211 for direct actuator mounting. Below are standard configurations – non-standard sizes up to DN600 available to order.

Specification	Detail
Body Material	Ductile Cast Iron GGG40 / Stainless Steel 316L
Rotor Design	8, 10, or 12-vane open rotor, CNC-machined tips
Inlet/Outlet Size	DN150, DN200, DN250, DN300, DN400 (custom up to DN600)
Pressure Rating	1.5 bar max differential (tested to 2.0 bar)
Temperature Range	-20°C to +200°C (standard), +450°C (high-temp option)
Leakage Rate (air)	≤0.1 Nm³/h per bar differential (DN150)
Drive Options	Direct motor, gearbox, hydraulic motor, or pneumatic motor
Certifications	ATEX Zone 2/22, IECEx, FDA, EC 1935/2004 (food-contact)

Heavy-Duty Application Scenarios

Pneumatic Conveying Systems

Doebritz blow-through valves act as both feeder and airlock in dilute- or dense-phase pneumatic conveying lines. Typical setups include feeding pulverized coal to burners, cement to mixing towers, and plastic pellets to extruders. The valve’s straight-through airflow path prevents material hang-ups and allows higher solid-to-air ratios than drop-through designs.

Silo Discharging & Truck Loading

Mount Doebritz valves directly under flat-bottom or conical silos to regulate powder discharge into blow tanks or mobile feeders. The blow-through design creates a pressure seal while aerating sticky materials like hydrated lime, fly ash, or titanium dioxide – preventing bridging and flooding.

Dust Filter Collectors

For dust collector hoppers under high negative pressure (up to -0.5 bar), the Doebritz blow-through valve provides continuous dust removal without air in-leakage. ATEX-certified versions safely handle combustible dusts (St1, St2, St3 classes).

Frequently Asked Questions

Q: What is the maximum lead time for a Doebritz blow-through rotary valve with custom flanges?

A: Standard sizes (DN150 to DN300) with ANSI 150# flanges ship within 4-6 weeks. Custom flanges (DIN, JIS, or pressure ratings up to Class 300) add 2-3 weeks. Doebritz offers an express assembly service for an additional 20% surcharge – delivery in 10 working days.

Q: Can I get ATEX Zone 20 certification for the valve interior?

A: Yes. Doebritz provides full ATEX 2014/34/EU certification including Zone 20 internal (gas group IIC) and Zone 21 external. We supply a complete technical file with nameplate marking, installation drawings, and ignition hazard assessment reports – mandatory for European explosive atmosphere compliance.

Q: What is the maximum operating temperature for your stainless steel blow-through valve?

A: Standard PTFE lip seals allow continuous operation from -20°C to +200°C. For high-temperature applications (up to 450°C), choose our graphite-laminate packing or metal piston-ring seals – no thermal expansion seizure guaranteed. Water-cooled housings available for +450°C to +650°C range.

Q: Do you support non-Newtonian or semi-moist materials like filter cake?

A: Absolutely. Rotor pockets can be fitted with adjustable scrapers or flexible tips (silicone, polyurethane) to prevent build-up. For hygroscopic powders, we integrate nitrogen or dry air purge ports into the end cover design – eliminating caking and cross-contamination between batches.

Q: How do you verify leakage rate before shipment?

A: Every Doebritz blow-through valve undergoes a dual test: (1) Static pressure drop test at 1.2 bar differential for 30 minutes, and (2) Dynamic leakage measurement using mass flow meters at rated rotor speed. We provide a signed test certificate with each unit, showing actual leakage ≤0.1 Nm³/h/bar for DN150 models.