Pneumatic Conveying Guide: What is Pneumatic Conveying & How Does it Work?

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Pneumatic conveying is a cost-effective way to handle and transfer powdered and bulk granular materials with ease and very little loss. Its earliest use was around 1950 in Germany, and since then it has become a widely trusted and used process within a range of various industries such as; food and beverage, chemicals and detergents, renewables, pet food, and specialist materials.

This article will provide you with all the relevant information on pneumatic conveying, what it is, how it works, common applications, and a list of highly-regarded pneumatic conveyor manufacturers you can find in the United States.

Table of Contents

What is Pneumatic Conveying?

Pneumatic conveying is a method of transferring bulk granular materials from point A to point B through a series of pipes with very little loss. A pneumatic conveying system transfers these powders or dry bulk materials through an enclosed conveying pipeline using pressure differential gas flow (usually air), generated by an air movement device like a fan, roots blower, or air compressor.

To learn about the different types of air compressors, read our Types Of Air Compressors – Air Compressor Types & Applications guide!

How Does a Pneumatic Conveying System Work?

The principle of pneumatic conveying is based on the fact that bulk goods are able to be moved by means of air through a system of pipes. The flowing conveying air through the pipelines transmits a propulsion force on the dry bulk material and thus conveys it through the conveying system.

For pneumatic conveying to be successful, there must always be a pressure difference between the beginning and end of the system of pneumatic conveying pipe. In order to achieve this, conveying blowers or air compressors are utilized.

The height of the pressure difference to be applied to the application will typically depend not only on the length and layout of the conveying line but also on the concentration of the bulk material in the conveying line – the loading. The varying pneumatic conveying methods can be distinguished in terms of their loading in the lean (dilute) phase, strand phase, and dense phase conveying, but we’ll get into these further later.

Generally, one differentiates between suction and pressure conveying systems and the combined suction pressure conveying systems. This pressure in the conveying system is a negative pressure that forces the material and the positive pressure inside the equipment to move inside the pipe towards the endpoint.

Pneumatic conveyors work inside a fully enclosed pneumatic conveying pipe, which typically lacks a rubber conveyor belt, which many people often confuse. They work like this in order to prevent fine powdered materials from spilling or escaping into the air and getting stuck between the mechanical components of a conveyor belt.

Advantages vs Disadvantages of Pneumatic Conveying

Advantages of Pneumatic Conveying

Pneumatic conveying systems boast many advantages over mechanical conveying systems in that they have a compact nature and so, they can be routed around existing equipment, providing more flexibility. They can not only be run horizontally but also vertically over a long distance.

Due to the fact that pneumatic conveying systems are closed systems, they are protected against dust emissions into the atmosphere and are able to protect the conveyed bulk material against external contaminants. These systems are easier and more cost-effective to maintain than mechanical conveying systems due to having fewer moving parts. This also provides the minimization of system wear, prolonging the system’s life span.

Pneumatic conveying equipment provides the user with the ability to maintain a controlled atmosphere around the bulk material being conveyed, along with taking up far less floor space and the option of having multiple picks and discharge points.

Disadvantages of Pneumatic Conveying

Of course, there will always be some disadvantages. Pneumatic conveying systems are less efficient compared to mechanical conveyors because they must change the air pressure to produce the conveying power. Some materials, like sticky or wet materials, or materials with high bulk densities and larger particles, may not be possible to convey within a pneumatic powder conveying system.

Pneumatic conveying equipment is designed to transfer smaller volume throughputs of materials and may face some challenges when conveying higher volume throughputs of materials. In some cases, it may be necessary to install a large dust collection system to extract dust at the end of the pneumatic powder conveying system.

Types Pneumatic Conveying Systems: Dilute Phase vs Dense Phase

When it comes to the different types of pneumatic conveying systems, we will focus on the following two of the most commonly found and used methods:

  • Dilute Phase Conveying
  • Dense Phase Conveying

A third and maybe less known method is lean phase pneumatic conveying, though some people refer to dilute phase conveying as a type of lean phase conveying method.

Dilute Phase Conveying

Dilute phase conveying is probably the most common method of pneumatic conveying. It typically gets its name from its ability to use compressed air or a vacuum to dilute materials by suspending them in a conveyance channel flowing through a pneumatic conveying pipe and preventing them from making prolonged contact with its surfaces.

In turn, the materials are then able to flow without any obstruction from point A (the source) to point B (the destination). Dilute phase conveyors use high pressure and they work best when transporting bulk materials over a long distance.

Dense Phase Conveying

Dense phase conveyors, on the other hand, are designed to handle the transportation of larger materials, and so, they sometimes may not feature vacuum or compressed air mechanisms, but in most cases, they will still. Objects will slide along the bottom of the conveyance channel instead of being agitated and suspended inside of the dense phase conveyor.

The configuration of a dense phase pneumatic conveying system greatly depends on its intended operation, and the properties of the bulk material it is working with. In most cases, dense phase conveyors work best with abrasive and fragile materials.

I have picked out a couple of useful YouTube demonstrations on dense phase pneumatic conveyor systems. The first is a pressure dense phase system and the second vacuum dense phase system.

Key Pneumatic Conveyor System Components

When looking at pneumatic conveying equipment, there are a few key components that are vital to the successful operation of any pneumatic conveyor system. The most important components include:

  • Feed system
  • Conveyor line
  • Gasesous flow equipment (air movers)
  • Solid gas separation equipment

The feed system is what sets the process off by feeding the bulk material into the gaseous stream as it blocks the gas from continuing on into the storage systems. The conveyor line sometimes referred to as the conducting line, then carries the bulk material down the line and through the entire system of pneumatic conveying pipe.

The solid-gas separation equipment or device will typically be a centrifugal separation, jet filters, or bags and it does exactly as the name implies, it separates the gas from the bulk material at the endpoint of the line. The gaseous flow equipment, sometimes referred to as air movers, is the device connected to the machine to provide the necessary flow of air to move the bulk material. This will often be a positive displacement blower, air compressor, or vacuum.

Other notable conveyor components include dust collection systems, chutes, diverter valves, rotary valves, end receivers, and terminations vessels.

Pneumatic Conveying Applications

Historically, pneumatic conveyor systems were designed in connection with the discharge of grain from overseas ships. Today, the systems are used for burner feeding with combustible dust and alternative fuels in the cement industry.

Pneumatic conveying can be found in the recycling sector, as well as the injection of alternative fuels in fluidized beds at power plants, and even pneumatic transport feeding in steel making.

The transfer of powders, granules, flakes, and other dry solid materials through enclosed conveying lines, utilizing air, is becoming more and more popular within various industries. When comparing dense phase and dilute phase conveying systems, there are a number of common applications.

Dilute Phase Applications

  • Flour and other non-abrasives
  • Materials with light bulk densities
  • Products that are not easily breakable

Dense Phase Applications

  • Abrasive products like sugar
  • Blended products such as detergents
  • Friable products like carbon black prills
  • Products that have heavy bulk densities
  • Products that do not require continuous delivery to their destination

Pneumatic Conveying Important Considerations

There are some important considerations to be aware of when selecting a pneumatic conveying system that is right for you. It will certainly be helpful to bring some basic specifications to your supplier if you are interested in pneumatic conveyor systems. It’s important to note that the process of pneumatic conveyor selection is difficult, and this list is only a basic overview of the most important values.

Distance, Flow Rate, and Pipe Design

It is important to know the distance you intend your material to be traveling, at what desired flow rate, and the design of the desired setup. There is typically far more mathematical analysis needed for pneumatic conveyors compared to most others, so the more information you understand and can provide, the better.

Think about variables such as pipe size, line length, product density, air mover flow rate, and many other values that will influence the effectiveness of the pneumatic conveyor. It’s ever so important to detail the number of bends, inlets, and outlets in the system – estimate these if you can, as well as understanding the characteristics of your material.

If you are unsure of what you will need, always fall back on the application and determine your end goal. Ask yourself, how much product do you want to be moved in a certain period? Your supplier knows best, they can undoubtedly help you work backward and determine the necessary values needed for what you are aiming to accomplish.

Filters, Fans, Vents, and Protection

If your bulk material is excessively dusty, aeratable, or toxic, it will be important that you use the correct filtering equipment to protect both staff and the system itself. Improper filtering is likely to lead to some damaging issues, including repairs and replacement. Therefore, it is crucial to ensure there is an adequate amount of filters and vents installed to keep the system running smoothly.

The fan selection process will typically depend upon the bulk material, the length of the conveyor line, and will also impact the life span of the conveyor system. Therefore, it is recommended to only use the minimum velocity required to move your product.

Control & Special Considerations

Pneumatic conveyors can be controlled via closed feedback or other similar control systems, so you must make sure that your supplier knows if your applications require this. Also, make sure that the system has adequate instrumentation that will allow for troubleshooting in the face of errors.

The functionality of these conveyor systems is highly dependent upon the material that they are conveying, and so you must know the working characteristics of your bulk material, as well as any potential variation between batches of the same bulk material.

Pneumatic Conveyor Manufacturers

Some notable leading manufacturers of pneumatic conveyor systems across the United States include:

  • Delfin Industrial Vacuums
  • Dynamic Air, Inc
  • Spiroflow Systems, Inc
  • VAC-U-MAX
  • VOLKMANN, Inc

Delfin Industrial Vacuums

Delfin Industrial Vacuums has been a leading pneumatic conveyor manufacturer for over twenty-five years.

Address

Delfin Industrial Vacuums
2010 E Center Circle, Bldg C
Suite 300
Plymouth, MN 55441

Phone

1-877-359-7509

Dynamic Air, Inc

Dynamic Air has long produced custom designs and manufactured a complete line of pneumatic conveying systems for dry bulk granular materials over the years. They offer 16 different pneumatic conveying concepts, utilizing both pressure and vacuum air movers, for handling a wide variety of dry bulk solids to provide a conveying solution that fits the process perfectly.

Address

Dynamic Air Inc.
1125 Willow Lake Blvd.
St. Paul, MN 55110
USA

Phone

1-651-484-2900

Spiroflow Systems, Inc

Spiroflow Systems has more than 40 years of experience in the design, manufacture & installation of bulk material handling equipment & conveyor systems.

Address

Spiroflow Systems, Inc.
1609 Airport Road,
Monroe
North Carolina 28110

Phone

1-704-912-1013

VAC-U-MAX

VAC-U-MAX is a premier custom pneumatic conveyors manufacturer of support equipment for conveying, batching, and weighing materials. 

Address

VAC-U-MAX
69 William Street,
Belleville,
NJ 07109

Phone

1-973-759-4600

VOLKMANN, Inc

Volkmann designs and manufactures hygienic, explosion-proof pneumatic vacuum conveying systems to safely transfer powders, pellets, granules, tablets, and other bulk materials from one point in a process to another while safeguarding particle integrity and mixture homogeneity.

Address

Volkmann, Inc.
1900 Frost Road
Suite 102
Bristol, PA 19007

Phone

1-609-265-0101

How does a pneumatic conveying system work?

The principle of a pneumatic conveying system is based on the fact that bulk goods are able to be moved from point A (the source) to point B (the destination) by means of air through a system of pneumatic conveying pipes. The flowing conveying air through the pipelines transmits a propulsion force on the dry bulk material and thus conveys it through the conveying system.

What is pneumatic conveying?

Pneumatic conveying is a method of transferring bulk granular materials from point A to point B through a series of pneumatic conveying pipes with very little loss. A pneumatic conveying system transfers these powders or dry bulk materials through an enclosed conveying pipeline using pressure differential gas flow. This gas flow in most cases will be air and can be generated by an air compressor, fan, or roots blower.

How to select a pneumatic conveying system?

The first consideration to help you select a pneumatic conveying system is the type of bulk material you wish to convey. You must know the material properties, such as bulk density, particle size, and shape, as well as knowing whether the material is abrasive, fragile, dusty, cohesive, or hygroscopic. This can have a significant influence on the system sizing and type of method used to convey materials, whether than be a dilute phase or dense phase.

What is a pneumatic conveyor?

A pneumatic conveyor is a system designed to move fine, dry bulk material from a start point to an endpoint using pressure differentials in a flow of gas, typically air and in some cases nitrogen. The material is totally enclosed within tubes or pipes, where differences in pressures on either side cause a flow of product.

What are the advantages and disadvantages of pneumatic conveyor?

Pneumatic conveyors boast many advantages in that they have a compact nature and can be routed around existing equipment, providing great flexibility. They can be run both horizontally and vertically over a long distance along with offering little spillage and dust leakage. However, since pneumatic conveying systems use an air stream to move materials through the system, they typically require more power to achieve the proper air pressure to do so. Some larger, denser, or sticky materials may also be difficult to convey, causing a buildup within the pipeline.

Where is pneumatic conveying used?

Pneumatic conveying is used across a whole range of industries such as food and beverage, chemicals and detergents, renewables, pet food, and specialist materials.


If you have any questions regarding pneumatic conveying systems, please leave a comment below, with a photo if applicable, so that someone can help you!

By Aidan Weeks

A passionate Mechanical Engineer with endless enthusiasm for fluid power - building off the back of over 18 years of high quality contribution and discussion stimulated by Bill Wade here at About Air Compressors. With both practical and theoretical experience in pneumatics and hydraulics, I'm putting my knowledge to work - and working my grey-matter through my research, assistance and publishing work here at About Air Compressors. Feel free to reach out any time! P.S. A HUGE shout out to Doug who really offers such great value to all visitors to About Air Compressors - once again, feeling like I'm standing on the shoulders of GIANTS by getting to work alongside such a great community

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