Drop-Through Rotary Valve, Doebritz Heavy-Duty Airlock, Cast Iron / ATEX Certified / Low Leakage

Product Summary

Doebritz Drop-Through Rotary Valves are precision-engineered for continuous unloading of powders, granules, pellets, and flaky materials in dense-phase or dilute-phase pneumatic conveying systems. Available in cast iron and stainless steel, with capacities up to 50 m³/h (based on rotor speed and material density). Our ATEX-certified design (Zone 22 internal / Zone 21 external) ensures safe operation in explosive dust atmospheres. Maximum pressure differential: 1.5 bar. Maximum temperature: 280°C with high-temp seals.

Why Source Doebritz Drop-Through Rotary Valves

• Ultra-Low Air Leakage: Precision-machined rotor tips and housing bores achieve leakage rates as low as 0.005 m³/m²/h at 1 bar, minimizing air loss and energy waste.
• Heavy-Duty Longevity: Outboard bearings isolate the bearing housing from the material flow, preventing contamination and extending service life by up to 3x compared to inboard designs.
• CNC Precision & Global Compliance: Every housing and rotor is CNC-machined for perfect concentricity. Full traceability from our ISO 9001:2025 certified plant. ATEX, FDA, and EC 1935/2011 compliant options available.
• OEM & Customization Ready: We support non-standard flanges (DIN, ANSI, JIS), special rotor coatings (Tungsten Carbide, Nickel), and variable-speed drives – all with 4-week lead time for most configurations.

Housing & Rotor Engineering

The Doebritz drop-through design features a one-piece cast housing (GG25 or CF8M stainless steel) with integrally cast inspection ports. The 8-vane open rotor is dynamically balanced and features renewable tip seals (PTFE, NBR, or Viton) that can be replaced without removing the rotor. Our patented tapered rotor bore prevents jamming from fibrous or sticky materials. All contact surfaces are polished to Ra ≤ 0.8 µm, reducing material build-up and friction heat. The double lip seal + air purge port configuration ensures zero dust migration to bearings, even under positive pressure.

Technical Specifications

All data below represent standard configurations. For non-standard bore sizes, materials, or explosion-proof requirements, contact our engineering team.

Specification	Detail
Inlet/Outlet Size	DN150, DN200, DN250, DN300 (custom others)
Body Material	Cast Iron GG25 / Stainless Steel 304 / Stainless Steel 316L
Rotor Design	8-vane open rotor, CNC-machined, dynamic balanced
Max Pressure Differential	1.5 bar (standard), 3.0 bar (reinforced)
Max Operating Temp	280°C (high-temp seals) / 450°C (graphite + purge)
Leakage Rate (air)	<0.005 m³/m²/h at 1 bar differential
Drive Options	Direct motor, gear motor, inverter ready, explosion-proof motor
Certifications	ATEX Zone 22/21, FDA, EC 1935/2011, ISO 9001:2025

Heavy-Duty Application Scenarios

Pneumatic Conveying Systems

Ideal as both a feeder and airlock in dilute-phase or dense-phase systems handling cement, fly ash, plastic pellets, or carbon black. The low leakage rate maintains system pressure while ensuring consistent material flow.

Silo & Hopper Discharging

Mounts directly under silos or bins to provide metered, starvation-free discharge of free-flowing and non-free-flowing bulk solids. Optional venturi housing improves flow of cohesive powders.

Dust Collectors & Filter Receivers

Used as a rotary airlock on dust collector hoppers to continuously remove collected dust without breaking the negative pressure. ATEX-certified units are mandatory for combustible dusts like wood, grain, or chemical powders.

Frequently Asked Questions

What is the standard lead time for a Doebritz drop-through rotary valve?

Standard cast iron models (DN150 to DN300) are available within 15 working days for stock configurations. Stainless steel or ATEX-certified units require 25 working days. Large orders (≥50 units) or custom flange patterns may add 10-15 days. We offer expedited production for emergency replacements at +20% cost.

Can you supply non-standard inlet/outlet flanges?

Yes – 100% customizable. We regularly machine to DIN, ANSI 150#, ANSI 300#, JIS 10K, and customer-specific bolt hole patterns. Minimum order quantity for non-standard flanges is 5 pieces. Just provide your flange drawing or dimensional sketch.

Is an ATEX certificate included for explosion-proof versions?

Absolutely. Each ATEX-certified Doebritz valve comes with a Declaration of Conformity and EC Type Examination Certificate (Ex h II 1/2 D T4, suitable for Zone 20, 21, 22). Certificates are issued by an EU Notified Body and are fully traceable via the serial number engraving on the housing.

What high-temperature options do you offer?

Standard seals (Viton) operate up to 200°C. For high-temperature applications (e.g., hot cement or calcined materials), we provide graphite-laminate seals and labyrinth purged with nitrogen, allowing continuous operation up to 450°C. Housing expansion gaps are pre-calculated to prevent jamming. Contact our application team for a thermal evaluation.

Do you offer repair kits or spare parts?

Yes – we maintain a global spare parts inventory including rotor tip seals, bearing assemblies, lip seals, and drive adapters. A standard wear parts kit (seals + bearings + gaskets) is available off-shelf for all models produced in the last 12 years. For critical installations, we recommend keeping one full seal kit per valve on site – lead time for kits is typically 5-7 days.