Which is better: aero mechanical conveyors or pneumatic conveyors?
Here at Spiroflow, we’ve been in the bulk material handling industry for more than 45 years. Given our experience, we find that aero mechanical conveyors are often a better option in many different types of processes. That being said, we’ve sold both types of conveyors over the years, and it’s important to first consult an engineer to understand if mechanical conveying (mechanical part moves material) or pneumatic conveying (air/gas moves material) is the best way to move your material. To help you understand the benefits of aero mechanical conveyors, we’re putting them up against pneumatic conveyors in today’s showdown.
Mechanical vs. Pneumatic: 6 Round Showdown
It’s time to settle the score. But first, some definitions.
What is an Aero Mechanical Conveyor?
An aero mechanical conveyor, or AMC, is a tubular conveyor that utilizes a cable and disc assembly. The movement of the conveyor is so rapid it aerates the product. As a general rule, each pocket contains about 80% air and 20% material.
It is one of the most efficient methods of conveying materials. Its dust-free and clean handling properties make the conveyor a good fit for many applications across several industries.
What is a Pneumatic Conveyor?
A pneumatic conveyor conveys material in a suspended stream of gas, usually air. When particulate materials are metered into an airstream, at an optimal solids-to-air ratio, the differential air pressure generated via a vacuum pump creates a high enough velocity to move the materials within the conveying tube.
Pneumatic conveying is a simple option to move material across challenging routes. The product is moved hygienically and is a good fit for several applications.
6 Rounds: Differences Between
Aero Mechanical Conveyors and Pneumatic Conveyors
Now, I’ll evaluate several characteristics that are important in considering the right conveyor for your dry bulk material handling needs. I’ll start with energy consumption, noise levels and venting.
Round 1 -Which conveyor is more energy efficient?
Is limiting power consumption a priority? Aero mechanical conveyors can convey material at a rate from 9 ft3/min (11.8 m3/hr) to 36 ft3/min (51.9 m3/hr) depending on the diameter of the tube. These conveyors can pull this off by using a drive motor between 2-7.5 hp through a gearbox. Pneumatic conveyors require a 20-40 hp blower to reach comparable rates to an AMC.
Round 2 – Which conveyor is quieter to run?
Is noise a factor? Aero mechanical conveyors operate below 85 dBA. Pneumatic conveyors are much louder than AMCs. They must be remotely installed or have mufflers installed, adding to the cost of the system.
Round 3 – Which conveyor has a better venting system?
One of the major advantages of an aero mechanical conveyor is that it’s a balanced system. Ambient air is drawn into the conveyor along with the material and the material is discharged at the outlet of the conveyor. The displaced air is drawn back into the conveyor creating the balanced system. There are no special venting or filtering requirements because there is no pressurization at the discharge point.
Pneumatic systems handle venting differently. A receiver is utilized that requires venting off the motive air. Compressed air is also required for backwashing the filters and valves required for proper operation. Pressure systems require venting with filtration for the receiving vessel with exhaust entering into the surrounding area or vented outside the building.
Vacuum systems generally draw motive air from the surrounding area. It is important to determine if special air conditioning or additional climate control will be required in these areas. This could greatly increase the cost of heating or air conditioning and should be factored into your budget.
That’s 3 rounds for AMC.
Let’s continue our showdown.
Round 4 – Which conveyor is best for layout optimization?
Multiple inlets and outlets can easily be integrated with aero mechanical conveyors. When multiple outlets are used we recommend that the conveyor operates at half speed. This ensures that the material exits the conveyor properly. A tube valve at each outlet provides a smooth path for the ingredient to pass through.
Multiple outlets on vacuum conveyors require a separate receiver, its own pressurized air supply for filter cleaning as well as its own feed control valve and diverter valves. Additional piping is also needed to feed each individual usage point. Each receiving point requires venting of the motive air as well as filters, valves, diverters, and additional piping to direct product to each use point for pressure systems.
Round 5 – Which conveyor is best to prevent the separation of and maintain blends?
Aero mechanical conveyors are considered gentle conveyors. Pocket fill is typically 80% air and 20% material. The air stream carries the product around any corners in the system and mixtures are maintained throughout the conveying process.
Pneumatic conveyors use a similar air-to-material ratio. The entire length of the circuit is under the same pressure or vacuum. Because of centrifugal force, the product hits the walls of the tube hard. This can lead to degradation of the material and wear on the machine. Blends are more likely to separate while being conveyed over long distances.
Round 6 – Which conveyor is easiest to clean?
Aero mechanical conveyors will transfer virtually all of the material introduced into the conveyor. Air purging is an option to clear out any residual material. Another option is dry cleaning, running a material like salt inside of the conveyor. Wash gates and drains are included when the application requires the system to be wet washed. When wet washing the AMC creates an agitation effect, like a dishwasher, that completely washes the inside of the conveyor. The conveyor can run while empty to dry out.
Pneumatic conveyors are also easily cleaned. They can be dry cleaned using salt to scour the conveyor. For wet cleaning, a “pig” is pushed through the piping system using compressed air. Since both conveyors are easily cleaned, this round is a tie.
And the winner is…
While aero mechanical conveyors have considerable benefits across industries and processes, it’s difficult to say which conveyor will truly work best for your process without an engineer knowing more about your operation. Not all processes are the same. At Spiroflow, we have a team of engineers in the United States and the United Kingdom that can help you. Feel free to contact us if you have any more questions.