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WATER AND AIR FILLED RUBBER DAMS

Characteristics of water-filled rubber dam
  • Filling the rubber membrane through a water column (30 to 40 cm higher level than level in the dam).
  • In a filled up state, water-filled weirs form a shape of a tear due to the weight of the water. Because of that a concrete sill needs to be wider and the shape of the membrane is also longer.

water-filled rubber dam

 

Advantages

  • The weight of the water-filled dam prevents vibrations.
  • The entire height of the dam rises or lowers evenly.
  • It has the possibility of functioning without electric power.

 

Weaknesses

  • More expensive construction: a wider concrete sill, more expensive water pumps, more expensive pipelines due to a bigger diameter of pipes.
  • Manipulation takes more time (filling up and emptying the weir).
  • Freezing of the weir (the possibility of water freezing in the system).
  • Vandalism (puncturing, cutting).

Characteristics of air-filled rubber dams
  • A rubber membrane is filled with air blowers which create negative pressure up to 0.250 bar.
  • When inflated, an air filled-rubber dam forms a shape of a circle, which is why a narrower concrete sill is necessary. The shape of the membrane of the dam is also shorter.

air-filled rubber dams

 

Advantages

  • Faster lowering and raising of the weir.
  • Cheaper construction.
  • Lower power consumption.
  • It can function with the help of photovoltaic systems

 

Weaknesses

  • Vibrations of the weir (setting up deflectors).
  • Uneven emptying of the weir (sinking of the centre of the weir).
  • Vandalism (puncturing, cutting).

Deflectors are used to break the water current and prevent the formation of the negative pressure below the water current of the weir. The negative pressure is the main reason for weir vibrations.




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