Inserting The Orifice; Inserting And Placing Connections; Backfilling - Graf VS-Control External Serie Manual De Instrucciones

5.4

Inserting the orifice

The GRAF vortex flow control shafts VS-Control External are packaged project-specifically. Usually, the
project-specific orifice is already located on the same palette like the VS Control External vortex flow con-
trol shaft body. The orifice has to be inserted into the vortex flow control shaft body from above. It must be
ensured that the orifice lies level and horizontally in the vortex flow control shaft body.
It must be ensured that the orifice lies horizontally in the vortex flow control shaft body.
Note:
If the catchment area or the size of the upstream retention tank is changed, the throttle dis-
charge can be adapted to the new conditions by replacing the orifice.
For a new dimensioning of the orifice please contact GRAF.
If the Infiltration inlet module DN 400 or the Infiltration inlet module DN600 is used, it is not
possible to replace the orifice plate later.
5.5

Inserting and placing connections

The vortex flow control shaft must be installed in a horizontal position in the prepared excavation pit and
connected to the appropriate pipes.
The vortex flow control shaft must be horizontal to guarantee its function.
The inlet line to the vortex flow control shaft must be straight with a minimum length of
1000 mm. The inlet and outlet pipes must be formed with a slight gradient of ~0.5 %. The
outlet line must be straight up to the next shaft with a minimum length of 5000 mm. This
length can be reduced on request. Please contact GRAF. The positioning of fittings or other
devices which hydraulically influence the free water discharge behind the vortex flow control
shaft is not permitted. A backlog must always be ruled out.
5.6

Backfilling

The casing of the vortex flow control shaft is produced in layers with round grain gravel (grain size 8/16
according to DIN 4226-1) in a width of approx. 300 mm. No backfill material may get into the shaft. The
individual layers are applied at a height of 300 mm and then compacted with a light compactor (hand
tamper).
The telescopic cover must be lined and vibrated accordingly so that no forces are transferred to the shaft
housing. Please pay attention to point 5.8.2 or 5.8.3 for car- or truck-accessible surfaces. Then the cover
is put on and closed childproof.
Ensure that the shaft system is in a horizontal position during backfilling.
The tangential inlet must be carefully lined and must also be horizontal after backfilling.
Damage to the housing must be avoided at all costs during compression.
5. Installation and assembly
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