Everything You Need to Know About Self-Contained Air Conveying Systems

Many industries rely on the effective technology of conveying systems to store and transport their dry bulk products. Products ranging from coffee beans, to small plastics, to dry dairy, grains, and more can all be stored and transported through these systems. In this post, we overview everything you need to know about Central Powered Vacuum/Pressure Conveying and Self Contained Vacuum conveying systems so you have a clear picture of the best products to support your business. 

An Overview of Conveying Systems

Pneumatic Conveying (also known as air conveying) is the transport of bulk solids in a pipe by a positive or negative air stream. How does it work?

Air Conveying Requires:

  • A pressure differential to cause air movement.
  • High-velocity air mass that forces materials to move fast enough to overcome frictional forces.
  • Kinetic energy transfer from gas to solid.

Conveying Capacity Depends On:

  • The product’s bulk density. This is the mass of the particles of the product being transported.
  • The energy content of conveying air through the entire system. This is the power of air needed to move the product through the system. 
  • The convey line diameter. Line diameter refers to the size of the pipe system transporting product and will depend on the size of your product. 
  • The convey line length. Line Length is the distance from where the product enters the system, to where it leaves it. 

Let’s look at an example. If you use an air conveyor that moves bulk coffee beans, the conveyor will be designed with enough power so that air pushes all the coffee beans from the dump station, sometimes called feed bin, through the conveyor line, to the receiving bin, where the product exits the system. In the coffee example, the beans leave the conveyor at this point and are deposited into bags or other storage containers to be transported to a coffee shop, or retail location.    

Advantages of Air Conveying:

  •   A straight conveying path is not required.
  •   The system can cover long conveying distances in a single conveyor.
  •   The system is totally enclosed.
  •   Conveyors are sanitary and easy to clean.
  •   They are safe to operate.
  •   Air Conveyors have a reduced fire and explosion hazard.
  •   They have minimal maintenance requirements.

Basic Methods of Pneumatic Conveying:

Pressure – Using Air under pressure as a conveying medium.

Vacuum –   Using Vacuum air to create suction as a conveying medium.

The best method will depend on the product you are conveying. Our product experts at Pneu-Con can help ensure you have a system that conveys your product efficiently and safely. 

Self-Contained Vacuum Conveying System (SC System):

In today’s dynamic commercial industry, many business owners require a customized solution to store and transport their goods. Additionally, these solutions are often needed in short notice as demands shift. 

This calls for a standardized product that can be manufactured in short notice, but at the same time can be adapted to meet the specific customer’s needs. Pneu-Con’s Self-Contained Vacuum Conveying System is uniquely positioned to meet this challenge. Our Self-Contained (SC) Systems are tailored to each client’s individual needs by judiciously selecting the design configurator and arriving at a unique model. Pneu-Con has all the parts available to make specific customized products in the shortest possible time. 

The Three Main Components Of A Self-Contained Conveying System

Let’s investigate the necessary components of a highly functional SC System. The main component of a Self-Contained Vacuum Conveying system is the product receiver’s internal motor/fan which serves as a vacuum-air source to move the product through the system. 

The next crucial part is the feed source from where the product is picked up. The feed source can be a feed hopper, bulk bag unloader, or bag dump where the product is picked up by a conveying adapter or a pickup lance.

The third part is the destination which receives the product from the filter receiver. The receiving station can be a hopper that feeds a filling machine; or can be an extruder, mixer or any other point of usage. For some applications where a continuous supply of material is required, a transition hopper is part of the SC System. In some cases, the customer’s machine can directly receive the product in pre-measured batches.

The SC Receiver (also called Whisper® Loader™ ) is designed to automatically convey material from a local source (typically located within 10 feet) to a machine material hopper or extruder. These receiving vessels are also referred to as ‘Day’ bins. 

self contained unit size selection graph

As a custom option, the SC Vacuum System can be supplied with a compressed air reverse pulse (Vibra-Pulse ) filter-cleaning system to automatically clean the filter.

SC Vacuum Systems operate on a batch principle. The duration of the conveying (run-time) and discharge cycle (dump-time) is determined by the PLC controller which comes standard with the SC System.

One unique and effective component of our SC Vacuum System is that the conveying-cycle frequency is “on demand” and will continue to convey material whenever the level in the receiving vessel falls below the point of the Receiver’s discharge Valve Flap, thus allowing it to close. Once the discharge flap Valve swings open, the Proximity Switch no longer senses the presence of the Valve’s Arm, in-turn signaling the Controller to stop Conveying. For the consumer, this means automated conveying and increased efficiency. 

Numerous SC Vacuum System options are available beyond the Standard base model including options to cater to each customer’s needs. For example, our conveying systems are designed to transport a variety of filtration media, offer multiple receiver working capacities, and can handle a wide range of products to ensure food-grade certification or other industrial requirements. 

The Standard SC Vacuum System PLC Control Panel can be configured for various functions, including auxiliary equipment controls for interfacing with customers’ equipment.

Limitations of Self-Contained Vacuum Loaders

A typical SC Loader efficiently transports dry bulk goods in the following range (any exceptions are subject to Pneu-Con engineering review):  

  •   Product Transfer Rates: 100-3100 LB/HR
  •   Conveying Distances: 5FT-35 FT
  •  Product Bulk Density Range: 10-65 LB/FT3

If your conveying needs fall outside of these limits, contact our sales team to discuss options that are more appropriate for your product. 

Central Powered Vacuum/Pressure Conveying System (CP System)

As the name suggests, a CP System has a remote air mover to provide pressurized conveying air. This differs from the SC units described above which use a built-in vacuum pump. Read on to see why a CP System is a versatile air conveying system with a very wide application range. 

Central Powered Pneumatic Conveying System Common Practices:

CP systems can be either pressure systems or vacuum systems. Often, they use a system called Dilute Phase Pressure which is the process of moving non-fragile materials (think: flours and powders) through a pipe powered by small amounts of gas at a high velocity. 

Pneumatic Conveying by Dilute Phase Pressure is used when:

  •     Conveying products from a single source to one or more destinations.
  •     The product has high conveying capacities.
  •     Conveying over long distances.
  •     You want to keep power consumption to a minimum.
  •     The product is responsive to material feed changes.

Air Conveying by Dilute Phase Vacuum is used when:

  •     Conveying from several sources to one destination.
  •    Conveying distances <300’.
  •     There is limited space at inlet points (railcars, for example).
  •    Using a venting pressure system creates problems.
  •    The materials have a light bulk density.
  •     Prioritizing feeding ease.
  •     The conveying capacity is limited to 1 atmosphere.
  •     There is a slow response to material feed changes

Types of Air Conveying

  •   Dilute Phase – Low solids to air ratio and air velocity >2,000 FPM.
  •   Dense Phase – High solids to air ratio and air velocity 100-1000 FPM.

Note : The above are general guidelines only and actual design and selection process is dependent on the product characteristics and customer specific application needs and should be evaluated for each case.

Cp Conveying Systems Consist Of Four (4) Major Components

components of a central powered pneumatic conveying system
  • A Centrally located Vacuum-based or Pressure-Based Blower Package
  • Air & Material Conveying Lines
  • Material Loaders, Receivers, and or Surge Hoppers
  • Main Control Panel

The components listed above are designed to convey material from one or more locations (think Silos full of product being conveyed to filling machines or Hoppers). Typically these machines convey from 100 lb/hour. to 80,000 lb/hour and focus on conveying distances up to 300 feet or more. 

Pneu-Con CP Systems include

  •       Continuous conveying with rotary valve discharge
  •       Batch conveying with gate or butterfly valve discharge
  •       Available in Pellet, Vibra-Pulse™ or Powder Receiver designs

The Takeaway

At Pneumatic Conveying Solutions, we are committed to creating equipment that meets your unique air conveying needs. Whether it’s a Self-Contained system, or a Central Powered system, we continue to exceed our customer’s expectations and help their businesses thrive. Our collaborative approach results in equipment that is designed for your specific product, and therefore increases efficiency and profits. Connect with our sales team today to learn more. 

BV Sarma

Director of Technical Services
BV Sarma is the Director of Technical Services at Pneumatic Conveying and has over 25 years of experience in the industry. BV's expertise lies within the product lifecycle and engineering custom solutions that meet organizational goals from vision to launch.