Weir-Comparison
selection criteria
For the arrangement of water level limiters, such as
- ASK Weirs = Automatic float-controlled flap weirs
- GSK Weirs / stowage signs = weight-controlled stowage flap weirs / stowage signs (weight stoppers)
- ALH Weirs = Automatic Air-Operated Lifting Weirs
[table]
Bedingung, ASK-Wehr, GSK-Wehr/ Stauschild, ALH-Wehr,
Einstau/Rückstau vom Vorfluter, JA, NEIN, Fallprüfung
Entlastungsmenge Q > 2 m3/s, JA, JA, JA
Entlastungsmenge Q > 10 m3/s, JA, Fallprüfung, NEIN
zul. Stauzielschwankung =< 5 cm, JA, NEIN, JA*
zul. Stauzielschwankung 2 cm/s, JA, NEIN, NEIN
wirtschaftliche Bauwerksgröße, JA, JA, Fallprüfung
Einbau in vorhandene Bauwerke, NEIN, Fallprüfung, JA,
[/table]
JA = klare Empfehlung | NEIN = sollte nicht eingesetzt werden | Fallprüfung = kann eingesetzt werden, ist aber jedesmal von Fall zu Fall zu prüfen
* Einschränkung in der Anlaufphase
Wertung der festen Wehrschwellen und Wasserspiegelbegrenzer: feste Wehre: Betonschwellen
Advantages:
- Simple design, even if the training of the sleeper head according to ATV-A 111 is done
- Low maintenance and upkeep
Disadvantages:
- Rigid plant
- Adaptation to changing circumstances hardly possible
partly enormous storage volumes of the pool or the network above the threshold up to the max. WSPs remain unused for retention
elaborate flood protection measures in the area of overflow height, ggflls. - Flood pumping station
long thresholds and thus large structures - Throttling of Qkrit required, otherwise large exceedances of Qkrit because of 30 – 50 cm higher WSP at Qmax, rising pool water level!
- Clearing overflow must be throttled
- Relief from the surface, for the retention of floating above coarse solids or fixed submersible walls are required
ASK-Weirs: Automatically Float-Controlled Jam Flap Weirs
Advantages:
- Accumulation target and max. WSPs are identical
- High selectivity for Qcrit for all outflow events up to Qmax
- Jam destination can be made variable
- Full use of the entire storage volume in the pool and in the upstream sewer network
- Flood protection up to max. WSP + approx. 0.40 m
- Compact structures, economical building sizes
- Underflow weir, relief from a relatively low polluted cross-sectional area
- Retention of floating coarse matter on the water surface through the weir trap
- Saving dipping walls and rakes
- No external energy required
- Operational safety, even with the largest systems (eg QBÜ> 20 m3 / s) at all times
- Lowest maintenance and service costs
Disadvantages:
- Installation in existing structures only possible with increased effort
GSK-Weirs: Weight-controlled jam flap weirs
Advantages:
- Accumulation target and max. WSP are almost identical
- High selectivity for Qcrit for all outflow events up to Qmax
- Use of the entire storage volume in the pool and in the upstream sewer system
- Flood protection to OK weir flap
- Compact structures, economical building sizes
- No external energy required
- Low maintenance and upkeep
lower system costs
Disadvantages:
- Adaptation to changing conditions by changing the counterweights restricted possible
- Overflowed system, discharge from the surface, for the retention of above-floating coarse solids or moving submersible walls are required
- If there is a backwater from the receiving water the stowage target can not be kept due to fluctuating water pressures on the weir flaps
- The rigid counterweights replace the water pressure of a certain difference between the upper and lower water, only when this condition occurs, the storage target is reached. In all other conditions with variable water level and thus water pressure differences, the accumulation target is too low (storage is not used!) Or too high (accumulation target is exceeded, back damage possible!) In conjunction with the dynamic forces at flow speeds of 3 – 5 m / s in the relief structures, congestion target fluctuations of up to approx. 0.20 m are possible.
ALH-Weirs: Automatic air-operated lift weirs
Advantages:
- Accumulation target and max. WSP are almost identical
- High selectivity for Qcrit for all outflow events up to Qmax
- Use of the entire storage volume in the pool and in the upstream sewer system
- Flood protection to OK weightlifter winder
- Underflow weir, relief from a relatively low polluted cross-sectional area
- No external energy required
- Low maintenance and upkeep
- Easy installation in existing structures by attachment to existing sleepers
Disadvantages:
- Rigid plant
- Adaptation to changing circumstances by changing the air control device only limited possible
- Relatively low efficiency, strongly dependent on the delta H between upper and lower water
- For larger discharge volumes long structures