Two flap shutters mounted one on top of the other form a Double-Flap Sluice.

The applications for Double-Flap Sluices are as follows:

  • When bulk materials are conveyed to another pressure level, such as the discharge from cyclones
  • When products or bulk materials are progressively cycled back and forth, such as with cement and glass production
  • If products or bulk materials in other processes or systems are progressively conveyed, such as in the entry or discharge in incineration or biogas plants

Double-Flap Sluice

Contrary to the Cellular Wheel Sluice, the Double-Flap Sluice has no difficulty with high temperatures, big grain sizes, large flow capacities and high difference pressures. It cannot block up, has almost no wear and tear and the foreign air due to clearance losses can be disregarded.

The Double-Flap Sluice is in particular suited for such cases where the charging is made into a higher pressure, since the difference pressure is pressing the flap against the outlet. Shall, however, the charging be made into a lower pressure, the lever system and the drive must be reinforced in case of higher pressure differences.

The Double-Flap Sluice is used for all kinds of bulk material and solid-liquid mixtures, when the container is to be completely emptied.

Container scales, container, primary and secondary vessels in mixing plants, wagons, reservoirs under filters and separators, cone worm mixers

The flap shutter is available in different designs, materials and compressive strength.

The Double-Flap Sluice operation is shown in the above section. By means of the lever system, the flap is vertically moved down and swivelled laterally by the side of the discharge opening, thus enabling a free discharge of the product.

The moving mechanics are situated outside the product stream, their standard execution is service-free (until approx. 200 degrees C).

The pneumatic design allows the flap quick opening, so that the product stream is not deviated.
Also in case of manually operated flap designs, large nominal widths can be opened quickly with low energy consumption at a high flap load.


Special features of the flaps are:

  • The sophisticated mechanism, no friction and shear forces occur on the seal, so that it does not wear
  • The closing flap swings completely from the product stream. The flowing product is therefore not damaged or modified
  • No wear of the flap develops dues to the flap swinging completely from the product flow


The Double-Flap Sluice operation is as follows:

  1. Basic position: Lower flap closed top flap open
  2. Conveying on the lower flap until the desired amount is reached
  3. Top flap is closed
  4. On systems with pressure differences between discharge and entry – carry out pressure compensation
  5. Open lower flap and discharge product or feed other production process
  6. Close the lower flap
  7. On systems with pressure differences between discharge and entry – carry out pressure compensation again
  8. Open upper flap. Double flap is back in normal position – lower flap closed, top flap open