Air Gaps Provide Frictionless Motion and Keep Particulates in Their Place
If your process involves bulk solids and powders, then you know first-hand how difficult they are to seal against. Particulates get lodged into any nook and cranny they can find, and if those crevices happen to be in your bearings, you’ll find yourself with unwanted clean up costs and maintenance downtimes.
Sealing Powders and Bulk Solids
The key is in the seal. If you can seal your process appropriately so that no unwanted material gets in or out then your problem is solved, but that is easier said than done. Contact seals are effective but usually require lubricants which can get past the seal. Additionally, the heat generated due to friction between the parts will eventually lead to wear.
Contact seals can be combined with non-contact options that utilize air pressure to create a seal. The gas pressure can be delivered via two methods, externally pressurized gas fed from outside or the gas can be drawn into the gaps through the relative motion between two surfaces. In order to create the lift necessary to operate frictionlessly, aerodynamic seals need to move at relatively high speeds, so are not ideal for use in powder applications. Another issue arises since the flow of air in these seals is across the seal face, meaning if the powder is on the side with the higher pressure it will want to travel across the face—penetrating the seal.
Aerostatic bearings also provide dry, frictionless motion but using externally pressurized air or gas passed through precisely placed grooves, holes, or orifices to create a thin film of air between a bearing or seal and another surface. A common setup in bulk processing is to have a throttle bushing with an annular groove along the inner diameter of the end. Gas or air fed into the ring doesn’t have a way to center the bushing on the shaft, so orifices are drilled through the bushing to provide equal and opposite compensation to center the bushing.
Holes in orifice bearings have to be drilled precisely and more holes means higher costs. You also run the risk of pressure gradients if the openings become scratched, or collapse if the gaps are too small and restrict air flow. Both of these situations have the same result—a costly crash.
A New Way to Seal
This is where Porous Media Technology™ from New Way® and external pressurization come into play. Our New-Seal™ Air Bearings rely on an external pressure source that is forced through our naturally porous carbon media. This creates a stiff cushion of air over the entire surface of the seal, meaning frictionless motion at any speed. Our bearings do not require any lubrication, produce no heat, and are crash-resistant.
Since the carbon substrate has millions of submicron holes throughout, the bearing surfaces can get very close together without restricting the airflow as in orifice bearings. This means our seals can achieve very high gap pressures. If the pressure in your bearing gap is larger than the pressure of your process, nothing from your process will be able to get past the air gap—creating an effective seal between powders or resins in your process and the bearings.
New Way New-Seal™ technology is a reliable and cost-effective way to have dry, frictionless motion with an impenetrable seal between your powders and bulk solids and your application components. Contact us today to learn more about how our porous media air bearings can seal your bulk process.