Revised Web Page - 2017 July 14

Over and Under pressure relieve valves


The function of the RULA Over under pressure relief valve is to eliminate any undesirable pressures in silos or hoppers and bins.

Silo Over under pressure relief valve are used to protect bins and silos from overpressure and under pressure damage. Under pressure collapse of a silo may occur if a column of material that has hung up in the silo suddenly dislodges and slides down creating a vacuum above the material. For the prevention of overpressure damage the valve would typically be fitted to bins and silos that are fed by a pneumatic conveying line or fed from a bulk tanker. A rubber seal on both flaps ensures an air tight seal.

The overpressure valve pressure and vacuum settings can be adjusted by changing the weights fitted to the sealing flaps. Standard settings are at +1.5 kPa and –1.5 kPa. The unit may not be used as a substitute for an explosion panel for potentially explosive products in the bin or silo.

Design Features

- Efficient system for pressure relief in silos etc.

- Less chance of damage to equipment and silos.

Material of construction specifications

- Body: SANS 50025 Grade S 275 JR

- Internals: SANS 50025 Grade S 275 JR


- Over under pressure relief valve are purpose made in any size and shape to fit plant requirements

- Drilling arrangement to suit plant interface piping

Operating & Maintenance

- The Over under pressure relief valve are Operator and Maintenance friendly

- A complete Operating & Maintenance manual is available

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