Selection Guide for Rotary Valves Handling Powder and Granular Materials

Selection Guide for Rotary Valves Handling Powder and Granular Materials

Rotary valves play a critical role in pneumatic conveying systems by ensuring controlled feeding, discharging, and air-locking. Below is a structured analysis of selection criteria for powder and granular materials, incorporating industry practices and technical insights.

I. Key Selection Criteria for Powder Materials

1. Recommended Types

• Blow-through Rotary Valves: Utilize compressed air to dislodge sticky powders (e.g., milk powder, flour) from rotor pockets, preventing buildup

• Sanitary Rotary Valves: Feature polished surfaces (Ra ≤ 0.8μm) and FDA/GMP-compliant designs for hygiene-sensitive industries like food and pharmaceuticals

2. Critical Design Features

• Anti-sticking Mechanisms: V-shaped blades or inclined planes minimize powder accumulation, while PTFE or hydrophobic coatings reduce friction

• Pressure Resistance: Enclosed rotor designs with dual-lip shaft seals withstand pressure differentials ≤0.6 MPa in dense-phase systems

• Speed Control: Low rotation speeds (20–30 rpm) prevent material backflow for poorly flowing powders

3. Applications

• High-Temperature Environments: Alumina ceramic coatings (heat-resistant up to 600°C) suit metallurgical or chemical reactor discharge

• Battery Material Handling: Stainless steel (SS316L) housings with nano-ceramic coatings prevent metal contamination (Fe <10 ppm)

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II. Selection Criteria for Granular Materials

1. Recommended Types

• Straight-through Rotary Valves: Optimized with large inlets and tilted angles to prevent jamming in free-flowing materials (e.g., grains, plastic pellets)

• Anti-jamming Valves: V-shaped inlets and chamfered blade tips avoid particle crushing, ideal for fragile granules

2. Critical Design Features

• Wear Resistance: Tungsten carbide coatings (HRA ≥85) or replaceable nylon/brass liners extend lifespan by 3x

• Multi-port Functionality: Separate compartments enable simultaneous handling of multiple materials (e.g., pet food lines) while isolating allergens

• Enhanced Sealing: Triple PTFE sleeve seals achieve leakage rates ≤0.1%

3. Applications

• Abrasive Granules (Quartz Sand): Tungsten carbide spray (≥2mm thickness) or alloy blades resist wear

• Sticky Granules (Sugar): U-shaped rotor pockets reduce material buildup in crevices

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III. Comparative Parameters

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