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Pneumatic Conveying

Pneumatic conveying systems transport powders, granules, dry bulk, and flakes through an enclosed conveying pipeline using pressure differential and gas flow (usually air) generated by an air movement device, for example, a roots blower, fan, or compressor.

Pneumatic conveyors provide a cost-effective manner to handle and transfer powdered and bulk granular materials quickly with very little loss. They are suitable for a range of process industries such as; Food and BeveragePet FoodChemicals and Detergents, Renewables, and Specialist Materials.

Pneumatic conveying system design - BulkInside - Innovations

A well-designed pneumatic conveying system is often a more practical and economical method of transporting materials from one point to another than alternative mechanical systems (belt conveyors, screw conveyors, vibrating conveyors, drag conveyors, and more) because:

  1. Pneumatic conveying systems are relatively economical to install and operate,
  2. Pneumatic conveying systems are enclosed and, if required, can operate entirely without moving parts coming into contact with the conveyed material. Being enclosed, these are relatively clean, more environmentally acceptable, and simple to maintain,
  3. Pneumatic conveying systems are flexible in terms of rerouting and expansion. A pneumatic system can convey a product where a pipeline can run.

There are several methods of transporting materials using pneumatic conveying.

In general, they seem to fall into these main categories: dilute phase, dense phase, and semi-dense phase.

Dilute phase pneumatic conveyors

Dilute phase pneumatic conveyors apply low pressure to move bulk material to send it to its destination at high speed through the conveying line. Dilute phase pneumatic conveyors can be either vacuum or pressure focused depending on the material to be transferred.

The dilute-phase system can be designed in three ways:

  1. Positive pressure system – Positive pressure systems operate above atmospheric pressure and convey bulk materials from a single source or multiple sources to one or multiple destinations, over medium distances, and with greater capacity than possible using vacuum systems.
  2. Negative pressure or vacuum system – Negative pressure or vacuum systems operate with air pressures below atmospheric pressure. Negative pressure (vacuum) is generally used to convey material from multiple sources such as storage vessels, process equipment, trucks, and rail cars, to an individual or various destinations.
  3. Combination of positive-negative system – This pull-push dilute phase system incorporates the advantages and benefits of both negative and positive pressure arrangements in a single design. These systems are used with multiple material entry points and delivery points.

Dilute phase pneumatic conveying systems are ideal with:

  • Non-abrasive and non-fragile materials with a light density
  • Certain batching systems
  • Examples: flour, cornstarch

Dilute phase pneumatic conveyors - BulkInside - Innovations

Dense phase pneumatic conveyors

Dense phase pneumatic conveyors offer the enormous advantage of effectively “pushing” a much thicker concentration of bulk solids at relatively low velocities through a conveying line.

The dense phase pneumatic conveyor is more commonly used to convey materials over longer distances and at higher throughputs. The limitations of air movement devices such as fans and roots blowers become prohibitive.

This method is also commonly used to convey fragile or abrasive materials at low velocities to minimize material damage or system damage. The low velocity of the dense phase means minor wear and tear on both the system and the materials being conveyed.

Dense phase pneumatic conveyors: contrary to dilute phase pneumatic conveyors, dense phase pneumatic conveyors apply high pressure achieving low speed. This is mainly because the material transferred is otherwise susceptible to coming apart.

Dense phase pneumatic conveying systems are ideal with:

  • Very fragile materials and mixtures, as the low speed and lower air volumes prevent materials from breaking down.
  • Best for low- or high-rate transfer of abrasive or brittle materials, as the slow convey speed reduces abrasion of conveying lines.
  • Slightly hygroscopic materials, without requiring the introduction of air drying equipment, because air quantities needed for the dense phase are significantly lower than semi-dense and dilute.
  • Examples: Sand, sugar, carbon black prill

Dense phase pneumatic conveying system design

Semi-dense phase pneumatic conveying

Semi-dense phase pneumatic conveyors: semi-dense phase pneumatic conveyors are a middle-ground solution developed to convey material at medium velocity.

As an intermediary step between dense and dilute phases, the semi-dense phase conveys materials using a medium velocity. Only a portion of materials is suspended in the air stream.

Semi-dense phase pneumatic conveying systems are ideal with:

  • Products in an aeratable state
  • Abrasive or friable materials
  • Examples: cement, fly ash

The decision of which pneumatic conveying system design is best for your operation should be based on the following questions:

  • What kind of material is being transported?
  • Is material or piping degradation a concern?
  • What is the purpose of the material transfer system?
  • Do you want to move the material?
  • Do you want to transfer more material than your current system can handle
  • Are you more concerned with reliability and efficiency or the gentleness of transport?

To answer these questions, you need to consider several material handling characteristics, including conveyability, optimum air-to-material ratios, buildup tendencies, flowability, and degradation.

Knowing how a material behaves during pneumatic conveying allows for the accurate specification of conveying mode (dilute or dense phase), gas flow and solids loading, and type of gas mover (for example, blower, fan, or compressor).

This Technology Zone offers an insight into the latest innovations in pneumatic conveying system design.

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Experts for Pneumatic Conveying

Carrie Hartford is the Technical Sales Manager and Senior Project Engineer in Jenike & Johanson’s office in California. For 15 years, she has been solving challenging bulk material flow related problems around the world. Typical projects include the analysis and design of bins, hoppers, feeders, and transfer chutes. From 2012 – 2014, she opened and established an engineering office and laboratory facilities in Perth, Western Australia. Internationally she publishes and presents technical papers, participates in conferences, and presents numerous short courses in the field of bulk solids flow. Carrie has a Mechanical Engineering degree from the University of California, Santa Barbara and an MBA from Azusa Pacific University in California. She is a licensed Professional Mechanical Engineer in the State of California.
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Doan Pendleton is Vice President of VAC-U-MAX located in Belleville, New Jersey. With over 20 years of professional experience in the design, engineering, manufacturing and marketing of dry bulk material transfer systems, Doan’s experience includes strong application knowledge of bulk ingredient handling systems for the food, pharmaceutical and chemical industries, as well as extensive experience with portable and central industrial vacuum cleaning systems. Mr. Pendleton holds a Bachelor of Science degree in Marketing/Marketing Management from Suffolk University. As Executive Manager, Mr. Pendleton manages Global Sales and Marketing.
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Sharon Nowak serves as Global Business Development Manager for the Food and Pharmaceutical Industries for Coperion and Coperion K-Tron. Nowak works closely with the Research & Development and Engineering departments as well as worldwide customer requests to identify new applications and provide design and focus on the very specific needs of these industries. Nowak has a 30+ year background in the process equipment industry for food and pharmaceuticals as well as a degree in Chemical/Biochemical Engineering from Rutgers University in New Jersey, USA. She has extensive experience designing and integrating feeders and material handling equipment including pneumatic conveying into continuous and batch processes for food and pharmaceuticals including blenders/mixers, mills/micronizers, extruders, granulators and coaters, and contained processes for potent pharmaceutical compounds.
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Matthew Bailey – Technical Lead

Matthew is a mechanical engineer holding an honours degree from the Auckland University of Technology and has been responsible for BFM® Global’s product development, testing and compliance programme for almost 5 years. Matt’s experience is centered on the powder handling industry with a specific focus on flexible connectors, and all the compliance requirements around them. From food to pharmaceutical and all industries in between, Matt works with our Distributor partners, end users and OEMs from Europe, Asia and the Americas to solve application challenges. He regularly attends industry tradeshows around the world and understands the complex requirements of each different market.
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Todd Messmer is the Product Manager for the Schenck Process Weighing and Feeding Product Line in North America. He has 21 years of Applications Engineering experience customizing and designing Screw Feeders, Weighbelts, Vibratory Feeders, Flow Meters, and Bulk Bag Unloaders into customers’ processes. Todd has worked with a diverse range of companies in the Food, Plastics, Chemicals and Pharmaceutical industries and has written several articles for key industry publications. He holds degrees in both Electronics and Marketing and currently manages a team of Applications Engineers for Schenck Process. Expert in Screw Feeders, Weighbelts, Vibratory Feeders, Flow Meters, and Bulk Bag Unloaders.
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Todd Allison is President of Progressive Products, Inc, where he spent 6 years being a sales engineer before moving into his current role. He is also a former adjunct professor in the Kansas Technology Center at Pittsburg State University, where he taught Innovation Engineering. Todd has spent most of his career in the pneumatic conveying industry and has almost 20 years of experience in industrial sales and product design. He is a graduate of SCAD design school and attended graduate school at the Kelce School of Business at Pittsburg State University. He serves on several advisory boards including the CEDBR Kansas Economic Outlook Team and the Mid America District Export Council.
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George Bougioukas, Plant Manager of Acmon systems has over a 20 years of experience in plant process design for both mechanical and automation engineering in a wide range of industrial sectors. He has gained a unique knowhow of cross-cutting technologies and applications bringing the organization to reach a new industrial value chain era. George’s expertise includes applications ranging from reception and storage of raw materials, pneumatic and mechanical conveying, sieving, weighing and dosing, mixing, up to bagging and final product dispatch. Behind George there is a dedicated team of engineers who like him are constantly striving to improve design and performance of all plants Acmon systems has been delivering all around the globe for the last 30years on a turnkey basis.
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Süleyman is General Manager of Polimak with more than 20 years of experience in design, engineering, manufacturing, and marketing of bulk solids handling systems. He leads the organization to provide problem-free solutions from single equipment to complete turnkey systems for a wide range of industries. Pneumatic conveying systems, dust collectors, rotary valves, big bag dischargers, batching & dosing systems, storage silos are some of the components designed and produced by a highly qualified engineering team in the organization. Holding a Bachelor’s Degree in Mechanical Engineering, Süleyman’s background includes software development, industrial automation, and IoT technologies. This facilitates Polimak’s vision of providing data-driven smart process technologies for the bulk solids handling industry in the new digital age.
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Aristidis Melios is the General Manager at Vraykos & Associates Mechanical Ltd. He holds a Diploma in Mechanical Engineering from National Technical University of Athens, and has more than 30 years of experience in design, engineering and manufacturing of bulk materials handling systems in food industry in Greece and Balkans area. Mr Melios is an expert in managing industrial projects that concern mechanical or pneumatic conveying, weighing & dosing, mixing, dedusting, screening and storaging of food bulk products. He has the experience needed to create a cost efficient turn-key solution for every bulk materials industry. The last years leads the Vraykos company engineering team with success, inserting new ideas and technologies in the field of bulk materials handling systems.
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More than 30 years’ experience in development and realisation projects as a project manager for feed, aqua feed and petfood. Working at Dinnissen for 20 years as account manager in feed, aqua feed and petfood division. Specialist in developing major projects with added value focussing on pneumatic conveying, mixing, drying, grinding and coating with liquid and powder systems.
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