Silo Pressure and Vacuum Protection Explained

Normal and Abnormal Pressure

During normal filling, the collector should keep silo pressure within the intended operating range. Abnormal pressure can develop from blinded filters, closed valves, a blocked outlet, excessive tanker air or overfilling product into the filter.

Vacuum can occur when material leaves rapidly, a fan extracts too much air or hot contents cool in a sealed vessel.

Layered Protection

• Correctly sized normal vent filter
• High differential-pressure alarm
• High and high-high level detection
• Filling permissive and automatic shutdown
• Independent pressure and vacuum relief
• Operating procedure and tanker communication

Relief Device Maintenance

Powder accumulation, corrosion, icing or poor adjustment can prevent a relief device from operating correctly. Mount it where it can be inspected and where discharge will not create a new hazard.

Do not use routine relief-valve opening as a normal venting method; investigate why collector capacity or condition is inadequate.

System Review

Confirm the silo design pressure and vacuum with the vessel supplier. Compare maximum credible inflow and outflow with vent and relief capacity. Include failure modes and simultaneous operations.

Document set points and test intervals during commissioning.