The oldest flow aid in the world is the hammer. People would hit their storage vessels to dislodge stuck material. It wasn’t very effective (or sanitary) because there would always be a little material left.
A pneumatic knocker is essentially an automated hammer. Compressed air pushes a piston against the vessel wall. But even if a pneumatic knocker automates the process, it doesn’t solve the problem. You will still have material residue, and you’re not guaranteed first in/first out flow.
The problem with hammers
Even if a pneumatic knocker uses air, its working principle is closer to an industrial vibrator rather than other pneumatic flow aids like AirSweep and fluidizers. In fact, it is often used in wet environments that would make an electric vibrator difficult.
But hitting vessels—whether it’s with a $10 hammer or an expensive pneumatic knocker system—will always cause more problems than it solves.
- Leftover material residue. Moist and sticky material will still cling to vessel walls. This can cause material spoilage and contamination, and affect batch consistency. Workers still have to periodic manual cleaning to completely flush out the material.
- Damage to vessels. The vibrations cause metal fatigue, which can damage thin vessels and lead to higher long-term maintenance costs.
- High noise levels. While not as loud as an air cannon, the sound of several pneumatic knockers banging on the vessel can stress out workers and may even cause deafness.
What a pneumatic knocker can (and can’t) do
A pneumatic knocker is effective for shaking off excess fine powder or water and releasing products from molds. It may also have very specific uses like preventing the adhesion of workpieces in a furnace.
However, if you’re looking for on-demand material flow, you need the true pneumatic flow aid—AirSweep.
AirSweep vs Pneumatic Knocker
AirSweep uses powerful air pulses that break up material blocks, pushes material back into the flow stream, and flushes the walls completely clean.
- Effective for all materials. A pneumatic knocker can only activate water and fine powders. AirSweep can move even moist powders, sticky compounds, or heavy bulk solids.
- No damage to the vessels. AirSweep can even be installed on very thin or small vessels—that’s how safe it is.
- No noise. The air pulses are just like a gentle hiss, and the sound is further muffled by the material in the vessel.
- Lower operating costs. AirSweep uses less plant air and energy than the air knocker, vibrator, or air cannon. It is the most energy-efficient flow aid you can find.
Drop the hammers
A food manufacturing company found that AirSweep was a more effective (and much quieter) alternative to hammers.
Bunge is an agribusiness and food ingredient company based in the USA. Rice bran was clumping in their hoppers and silos—a common issue for materials that hold moisture and are sensitive to humid environments. Workers had to hammer the vessels, which was ineffective and stressful for everyone in the factory. “It was like fingernails on the chalkboard. You wanted to get away from it,” said John Pappenheim, Bunge’s Maintenance Manager.
AirSweep instantly solved all material blocks. They had no clumping issues, no dents on machines, and no irritating hammering noises. The results prompted the company to install another system in their masa flour factory.
While Bunge used “traditional” hammers, this case study shows that hitting a vessel will not promote material flow—even if it is automated. AirSweep doesn’t just shake a vessel, it sweeps material into the flow stream.
Visit the AirSweep page to find out more about its features and what it can do for your process.