In modern industrial processing, transporting bulk materials efficiently, safely, and with minimal product degradation is critical. Dilute phase conveying is one of the most widely used methods for moving powders, granules, and light bulk materials through pipelines.
At AMH Technologies, we design and supply custom dilute phase systems tailored to a wide range of industries, ensuring optimal performance, minimal maintenance, and high product quality. This article explores everything you need to know about dilute phase pressure and vacuum conveying.
Professional dilute phase conveying systems for efficient bulk material transport
What is Dilute Phase Conveying?
Dilute phase conveying is a pneumatic system where bulk material is transported through a pipeline suspended in a high-velocity air stream. Unlike dense phase conveying, where materials move in plugs or slugs at low velocities, dilute phase keeps particles fully suspended in the airflow.
Pressure (Positive) Conveying
Air is pushed from a blower or compressor at the start of the pipeline to move the material toward the destination.
Vacuum (Negative) Conveying
Air is pulled by a vacuum pump or exhauster at the endpoint, drawing materials from multiple pickup points.
Advantages of Dilute Phase Conveying
- Flexibility in routing – Complex pipework with bends
- Reduced contamination – Enclosed systems minimize dust exposure
- Scalability – Easy to extend or modify pipelines
- Multiple pickup/delivery points – Versatile routing options
- Ease of automation – PLC and SCADA integration
Pressure vs. Vacuum Conveying: How They Work
1. Pressure Conveying
Operation:
- Material is fed into the pipeline via a rotary valve, screw feeder, or venturi feeder
- A positive displacement blower pushes material at high velocity (15–35 m/s)
- Air-material mixture is separated in a cyclone or filter at the receiving end
Advantages:
- High conveying speed and capacity
- Reliable over long distances
- Multiple destination points
Limitations:
- High velocity may damage fragile materials
- Requires robust pipelines for abrasive products
2. Vacuum Conveying
Operation:
- Material is drawn into the pipeline from bins, silos, or hoppers
- A vacuum pump at the receiving end creates negative pressure
- Material is separated from air using a filter receiver or cyclone
Advantages:
- Lower velocity reduces product degradation
- Minimizes dust leakage
- Flexible for multiple pickup points
Limitations:
- Limited conveying distance
- Typically lower conveying capacity
Key Design Considerations
1. Material Characteristics
- Particle size & shape – Irregular particles may settle faster
- Bulk density – Determines required air volume and velocity
- Moisture content – Sticky powders may cause blockages
- Abrasiveness – Requires wear-resistant pipelines
2. Pipeline Layout & Conveying Distance
- Longer pipelines increase pressure drop
- Pipe bends and vertical lifts require additional capacity
- Smooth bends reduce wear and maintain consistent velocity
3. Air Volume, Velocity, and Pressure
4. Feed & Discharge Equipment
Pressure Systems:
- Rotary airlocks
- Screw feeders
- Venturi feeders
Vacuum Systems:
- Pick-up hoppers
- Vacuum receivers
- Filter systems
5. Filtration & Dust Control
- Cyclones, bag filters, and HEPA filters prevent dust escape
- Food/pharmaceutical applications require hygiene compliance
6. Automation & Monitoring
- Level sensors, pressure sensors, and flow meters
- PLC or SCADA integration for automated control
Applications Across Industries
Food & Beverage
Flour, sugar, spices, coffee
Pharmaceuticals
APIs, excipients, powders
Chemicals
Pigments, additives, resins
Plastics
Pellets, regrind, powders