How to Reduce Wear on Screw Conveyor Hanger Bearings
28 September, 2026
For engineering teams managing bulk solids, selecting the right valve seal is the difference between a clean plant and a costly environmental cleanup. The most effective seal material depends on the abrasiveness of your powder and the operating temperature. For standard cement, NBR (Nitrile) is the reliable choice. For highly abrasive fly ash, Polyurethane (PU) offers the longest life, while EPDM is required for high-moisture or outdoor environments.
Selecting a seal requires balancing mechanical strength with chemical compatibility to prevent “dust blowouts” and material loss.
NBR is the industry standard for most silo accessories due to its excellent oil resistance and moderate mechanical strength. It performs well with non-abrasive mineral powders such as standard Portland cement and calcium carbonate.
However, NBR should be avoided in high-temperature applications. It can become brittle over time when exposed to constant friction from heavy aggregates or hot materials discharged directly from kilns.
In the hierarchy of wear resistance, Polyurethane (PU) stands at the top. It is the best material for handling fly ash, quartz sand, and other abrasive bulk solids that act like sandpaper on valve internals.
PU seals possess high tensile strength and superior erosion resistance. They are specifically recommended for valves installed in pneumatic conveying lines where high-velocity particles would quickly erode standard rubber.
EPDM is favored for its resilience against environmental factors. It is the preferred seal for silos located outdoors or in coastal regions with high humidity. It resists heat and steam much more effectively than Nitrile.
It is critical to remember that EPDM has poor resistance to oils. If your pneumatic system uses lubricated air, EPDM seals may swell and cause the valve to jam, leading to operational failure.
Use this table to match your specific material with the most durable seal option.
| Bulk Material Type | Recommended Seal | Primary Advantage |
| Portland Cement | NBR (Nitrile) | High cost-efficiency and reliable seal |
| Abrasive Fly Ash | Polyurethane (PU) | Maximum resistance to erosion |
| Hydrated Lime | EPDM | Resistance to heat and weathering |
| Food Grade Powder | Silicone / PTFE | FDA compliance and low friction |
| Hot Kiln Dust | Viton (FKM) | Stability in high-temperature zones |
Beyond the material itself, the mechanical interaction between the valve disc and the seal dictates the service life of the component.
A professional Silo Accessory Manufacturer like AKMK ensures the seal has the correct Shore hardness. A seal that is too soft will extrude under pressure, while one that is too hard will fail to create a dust-tight closure against the valve disc.
Even the best material will fail if the valve seat is uneven. We utilize CNC machining to ensure a perfect 360-degree contact surface. This precision prevents fine powders from migrating behind the seal, which is a common cause of valve jamming.
Since 2012, AKMK has focused exclusively on the unique challenges of bulk solid handling. We understand that a “one-size-fits-all” approach to seals results in frequent maintenance and lost productivity for batching plants.
As a dedicated Silo Accessory Manufacturer, we subject our EPDM, NBR, and Polyurethane seals to rigorous friction testing. This ensures our V1FS and V2FS series valves remain “fit-and-forget” components for our global partners.
Do you need to replace seals for your current silo valves? Contact us.
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