Siphon Data Fields
A siphon is an overflow structure that can consist of a single siphon tube or an array of identical siphon tubes. The siphon operates very like a weir structure when the water level is less than or equal to the siphon's Priming Level. Above this level the control operates as a siphon.
Siphon data can be edited on either the Siphon Grid Window of the Links Grid or the Siphon Property Sheet.
To view and edit all siphon data, use the Property Sheet.
This table describes all the siphon specific data which can be used to define a siphon. For details of results fields, see the Link Results Data Fields topic.
Common Data Fields Fields that are common to the majority of objects can be found in the Common Fields topic.
Siphon Data
Database Table Name: hw_siphon
|
Field Name |
Help Text |
Database Field |
Size |
Precision |
Default |
Error Lower Limit |
Error Upper Limit |
Warning Lower Limit |
Warning Upper Limit |
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Crest |
This is the level at which flow first starts to go over the siphon with the crest acting as a weir.
|
crest |
Double |
|
Z |
3 |
|
-9999 |
9999 |
|
6000 |
|||||||||||||||||||||
|
Crown level |
This is the internal top level of the siphon tube. The Crown level minus the Crestlevel gives the height of the siphon tube. |
crown_level |
Double |
|
Z |
3 |
|
-9999 |
9999 |
|
6000 |
|||||||||||||||||||||
|
Priming level |
This is the water level at or below which the siphon will operate as a weir. Above this level the siphon will operate as a primed siphon. You must satisfy the condition Crown level > Priming level > Crest level. |
priming_level |
Double |
|
Z |
3 |
|
-9999 |
9999 |
|
6000 |
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|
Outlet level |
Soffit level of the siphon tube outfall. The siphon is assumed to have a free outfall at this level, and not to be affected by tail water levels. If there are high tail water levels, you should estimate these and use the tail water level as the Outlet level |
outlet_level |
Double |
|
Z |
3 |
|
-9999 |
9999 |
|
6000 |
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|
Width |
The internal width of the siphon tube. The tube is assumed to be rectangular in cross-section. For circular cross-section siphon tubes, the Width is the cross-sectional area divided by the height (Crown level - Crest level). |
width |
Double |
|
L |
3 |
|
0.1 |
|
|
|
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|
Discharge coefficient as siphon |
This is used for primed flow when the water level is above the Priming level. It is used in the equation:
|
cd_siphon |
Double |
|
|
2 |
1 |
0.01 |
|
|
|
|||||||||||||||||||||
|
Discharge coefficient as weir |
This is used for weir flow when the water level is less than or equal to the Priming level. It is used in the equation:
When operating as a weir, the siphon behaves in the same way as a weir control with the same characteristics. However, the numbers you must enter are slightly different. The equation used for weir controls does not include the Ö2 term. Therefore the discharge coefficient you enter must be x for a siphon and Ö2x for an identical weir control. |
cd_weir |
Double |
|
|
2 |
0.544 |
0.01 |
|
|
|
|||||||||||||||||||||
|
Hood soffit level |
The level of the soffit hood. A transitional flow regime is applied as the siphon becomes primed. The simulation engine will linearly interpolate between the weir and siphon (primed) equation values between soffit hood level and priming level. When Hood soffit level ≤ u/s level ≤ Priming level, then during a simulation, flow is predicted using the following equation:
If a hood soffit level is specified, then it must be greater than the specified Crest but less or equal to the specified Priming level. If no hood soffit level is specified, the Priming level will be used. |
soffit_level | Double |
|
Z |
3 |
-9999 |
9999 |
|
6000 |
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|
Number of siphons |
You can define a bank of one or more identical siphons. This number must be at least 1. |
number_of_siphons |
Long Integer |
|
|
0 |
1 |
1 |
|
|
|
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|
US node ID |
Type in a node reference or choose an existing node reference from the drop down list. This makes up the first part of the link reference. |
us_node_id |
Text |
64 |
|
0 |
|
|
|
|
|
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|
Link suffix |
A single character between A and Z or 0 and 9 which completes the link reference. This allows a node to have up to 36 downstream links. The suffix is automatically allocated by the software. |
link_suffix |
Text |
1 |
|
0 |
1 |
|
|
|
|
|||||||||||||||||||||
|
DS node ID |
Type in a node reference, or choose an existing node reference from the drop down list. |
ds_node_id |
Text |
64 |
|
0 |
|
|
|
|
|
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|
Link type |
There are no additional options. The field is hidden on the grid, and read-only on the property sheet. |
link_type |
Text |
6 |
|
0 |
SIPHON |
|
|
|
|
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|
System type |
Choose the system type from the dropdown list. See System Type for more information.
|
system_type |
Text |
10 |
|
0 |
Other |
|
|
|
|
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|
Asset ID |
For reference only. Designed as a reference to an asset database, but could be used for anything. |
asset_id |
Text |
64 |
|
0 |
|
|
|
|
|
|||||||||||||||||||||
|
Sewer reference |
An optional reference to identify the sewer of which this conduit is a part. |
sewer_reference |
Text |
80 |
|
0 |
|
|
|
|
|
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|
Points |
This field defines the geometry of the link. The underlying data consists of a series of (x,y) pairs defining the vertices of the link. Each link is made up of a series of straight lines between the defined (x,y) points. This data is not displayed on the grid or property sheet.  Link Vertice Export
Link vertices are included when you export link data to CSV files. There are two options available for exporting link vertices. These are selected on the Select CSV Export Options Dialog using the Coordinate Arrays Format dropdown list. The options are:
|
point_array |
Array |
|
XY |
0 |
|
|
|
|
|
|||||||||||||||||||||
|
DS settlement efficiency (%) |
See US settlement efficiency. |
ds_settlement_eff |
Long Integer |
|
|
0 |
0 |
0 |
100 |
|
|
|||||||||||||||||||||
|
US settlement efficiency (%) |
The settlement efficiency fields allow you to set the effectiveness of an overflow for trapping out sediment. The overflow is a link (normally a pipe) attached to a node acting as a storage tank (storage node or manhole). Normally the upstream end of the link will be attached to the node and act as the overflow. The upstream settlement efficiency determines the efficiency for the overflow. In some circumstances the link may be reversed (storage tank at the downstream end) and the downstream settlement efficiency will be used. In many cases an overflow will attach to an outfall from the system. It would be very unusual to have both upstream settlement efficiency and downstream settlement efficiency set to non-zero values. The valid range is 0-100%. 0% means the overflow acts as a normal continuation link. 100% means that the overflow traps out as much sediment as possible. |
us_settlement_eff |
Long Integer |
|
|
0 |
0 |
0 |
100 |
|
|
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|
Branch ID |
Numeric field used to identify to which long section the link is associated. Can be set manually or automatically (see Defining Branches topic for more information). |
branch_id |
Long Integer |
|
|
0 |
|
0 |
|
|
|
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|
InfoAsset unique ID |
Unique ID associated with the corresponding object in an InfoAsset Manager database. When importing from InfoAsset Manager, the InfoAsset ID can be copied from the InfoAsset database in order to maintain links between the two networks. |
asset_uid |
GUID |
|
|
0 |
|
0 |
0 |
0 |
0 |
|||||||||||||||||||||
| InfoAsset ID |
Used to store the ID of the corresponding InfoAsset object when Importing from a Collection Network. |
infonet_id | Text | 40 | 0 |
Water Quality
