Our Approach

Our innovative approach to pneumatic conveying, developed in the 1970s, enabled the industry to move from dilute phase systems to dense phase systems. Our philosophy is to provide expertise to design and manufacture systems that are simple and reliable. This concept has transformed not only pneumatic conveying, but also our customers’ material handling capabilities and continues to be recognized as a proven and tested approach to low velocity, dense phase pneumatic conveying.

Our passion for science and understanding of how to best convey materials, especially those that are difficult to handle, has been critical to our success. This, combined with engineering that focuses on developing equipment with quality and customer benefits in mind, sets us apart from many other pneumatic conveying companies.


  • Expertise in low velocity for over 45 years
  • Extensive material testing – thousands of materials tested over the years
  • Continuous development of applications and designs
  • Working hand in hand with customers to educate and provide custom solutions
  • Optimization of design to create custom solutions

Our systems are designed to convey materials in the most suitable dense phase conveying regime to create the best conveying results and operating benefits. This, in turn, requires frequent cycles and a reliable feeding valve. The Dome Valve®, with the ability to close through a column of material and provide a bubble-tight seal, was developed and patented by Macawber in the early 1970s. It is a robust, inflatable seat valve specially designed for dense phase applications, and in particular, for extreme processes such as abrasive and high-temperature applications.

Butterfly and many other valves in the market cannot provide the same functionality and reliability in dense phase applications. The Dome Valve® is in the heart of every Macawber system, and with just one moving part, it is not only simple to operate, but it is also low in maintenance. In certain applications, the Dome Valve® is known to operate hundreds of thousands of cycles between inspections.

  • No Boosters

To create a stable and reliable dense phase conveying regime, the material must be permeable allowing the convey air to permeate through the material. There are two common approaches that this is achieved; by system layout or by installing boosters the full length of the convey line. Our approach is the system layout in how we distribute and control the convey air in and out of the vessel and our vessel size to pipe size ratios. In this arrangement, all common maintenance points are located at the vessel whereas maintenance points for boosters are located throughout the convey line with many difficult to access.

Generally, boosters are used when the conveyance regime is unstable, unreliable, and unpredictable. There can be various conditions that can produce this unreliable condition; 1) material physical characteristic, 2) particle distribution, 3) poor system pipe layout, and/or 4) general system arrangement.

  1. Material characteristic – the material does not retain air, poor flow characteristics, high friction coefficient
  2. Large material distribution with a small ratio between large and small particulate can create an impermeable slug preventing convey air from permeating through the material.
  3. Back to back elbows, excessive vertical lifts, conveying down then back up can slow material allowing the material to collect in a massive slug resulting in an impermeable slug.
  4. Poor pipe size diameter to vessel size will result in excessive slug length preventing air from permeating through the material.

While the addition of air (boosters) in the convey line can create permeability in the slug of material, it adds additional cost in both CapEx requiring an additional air manifold paralleling the convey line, and operating cost in additional air requirement and maintenance points throughout the convey line. Generally, these boosters are located at 10 ft. increments.

  • Low Profile Equipment

Our operating philosophy utilizes small pressure vessels. This has the additional benefit of installation flexibility, reduced steelwork, and support structure requirements, as well as the ability to fit into small spaces, under silos, bulk bag unloaders, reclaimers, etc.

Our expertise is widely used to design systems for difficult-to-handle materials such as abrasive, hot, sticky, and fragile materials. However, as almost all applications will benefit from the lowest material velocity providing the greatest energy efficiency, we have thousands of systems in just about every process industry offering value in terms of quality, simplicity, reliability, and cost savings.  Many of which have been in operation for over 20 years.