Cement Silo Butterfly Slide Gate

Function

Reliable shut-off at the silo outlet is essential for safe maintenance access to the screw conveyor, cement weigh system, and all downstream components. A gate that does not close fully allows uncontrolled cement flow that can fill and stall the screw conveyor under static head, overfill the weigh hopper, or create a cement dust and entrapment hazard during maintenance entry. In PLC-controlled plants the gate also protects the weighing system from uncontrolled trickle flow during batch controller idle periods between production runs.

Construction & quality

Gate bodies are cast ductile iron or fabricated carbon steel, flanged to PN10 or PN16 standard. The disc (butterfly configuration) or blade (knife-gate configuration) is cast iron or 316 stainless steel, faced with a vulcanised NBR or EPDM seat for powder-tight shut-off under cement head pressure. The stem is 316 stainless steel running in PTFE-lined bushings. Actuation is by a direct-mount double-acting pneumatic actuator with 3–5 bar supply pressure; a spring-return-to-closed (fail-safe) option is available for emergency shut-off on loss of air supply. Gate position is confirmed by two inductive proximity sensors wired to the PLC I/O panel. Internal gate surfaces are smooth-finished to minimise cement bridging and adhesion.

When to replace

• Cement trickle through the gate confirmed in the fully closed position
• Actuator unable to achieve full disc or blade closure against cement head — stroke incomplete
• NBR or EPDM seat showing visible compression set, cracking, or chemical degradation
• Excessive compressed air consumption per open/close cycle detected at air audit
• PLC fault indicating gate position sensors not confirming open or closed state within timeout