Industry
Vacuum and blowers for pneumatic conveying
A 2025 Jenike & Johanson article describes pneumatic conveying as moving powders and granules through pipelines with air or another gas; in dilute phase vacuum systems the air mover sits at the end of the line and pulls the material, and in positive pressure systems it sits upstream of the feed point and pushes it.
Vacuum or positive pressure
In an article of 3 September 2025, Jenike & Johanson compare the two configurations of dilute phase systems, in which the air mover is a fan, blower or compressor:
| Feature | Vacuum (negative pressure) | Positive pressure |
|---|---|---|
| Air mover | At the end of the line, downstream of the receiving point; pulls the material | At the start of the line, upstream of the feed point; pushes the material |
| Suited to | Dust control, shorter distances, stringent hygiene, pick-up from several feed points such as central dust collection | Inert gases, longer distances, higher capacities, delivery to several discharge points |
| Conveying distance | Typically a maximum of about 100 m | Up to about 300 m |
Dilute phase and dense phase
A 1997 review for the International Fine Particle Research Institute (IFPRI) notes that the majority of installed systems are dilute phase, with the particles transported at low concentrations, suspended in the transport gas. These systems give a simple means of enclosing the material and great flexibility in routing, but are often less energy efficient and more hostile to the material. Dense phase systems, in which the majority of particles are not suspended in the conveying gas, were developed to reduce these disadvantages; the review names blow tank systems, which feed the solids from pressure vessels, as probably the most common.
Jenike & Johanson give typical figures: dilute phase systems at conveying velocities of about 15 to 30 m/s and static pressures below about 1 bar; dense phase systems at feed point air velocities of about 3 to 10 m/s and static pressures of 2 to 10 bar, over distances typically up to about 600 m.
Blowers and vacuum pumps
In its background, US patent 11,815,105 (2023), on regenerative blowers, also referred to as side channel blowers, lists pneumatic conveying among their applications; see side channel blowers.
Ultra Controlo distributes and services Gardner Denver and Elmo Rietschle, two of its five partner brands. Its Industrial 2026 catalogue lists Gardner Denver screw compressors, blowers and integrated systems for heavy industry, and Elmo Rietschle vacuum pumps and blowers in vane, claw, screw and side-channel technologies, including side-channel blowers with an output of up to 3,000 m³/h and pressures up to 1,000 mbar.
More questions
When is vacuum conveying chosen over pressure conveying?
For dilute phase systems, Jenike & Johanson (2025) describe vacuum as offering dust control and suiting shorter distances, stringent hygiene and pick-up from several feed points, while positive pressure suits longer distances, higher capacities and several discharge points.
What is dense phase conveying?
A 1997 IFPRI review defines a gas-solids flow in a horizontal pipe as dense phase when the majority of particles are not suspended in the conveying gas.
Sources
- Jenike & Johanson, Dilute vs. dense phase: choosing the right pneumatic conveying mode for your bulk material (3 September 2025)
- D. J. Mason, M. G. Jones and L. Buchanan, Review of Dense Phase Pneumatic Conveying, IFPRI report SAR-91-01 (1997), summary
- US Patent 11,815,105 B2, Regenerative blowers-compressors with shaft bypass fluid re-vents (granted 14 November 2023), background
- Ultra Controlo, Medical gas answers: Does Ultra Controlo supply industry as well as hospitals?
- Ultra Controlo, Industrial 2026 catalogue, pp. 10 and 11
Ultra Controlo figures come from its technical datasheets. Third-party facts were read at the source on the date shown.