An orifice plate controls the discharge from a storage tank or pond. It consists of a plate with a hole, usually circular, for the flow to pass through.
An orifice plate is represented as a link of zero length, forming a head-discharge relationship between two nodes. The boundary condition between the link and a node is that of equal water levels. The orifice invert level determines when the control first comes into operation. The flow characteristics for the calculated flow from headloss through the orifice (before any limit on flow is applied) are identical in both the positive and negative directions.
This table describes all the orifice specific data which can be used to define an orifice. For details of results fields, see the Link Results Data Fields topic.
Fields that are common to the majority of objects can be found in the Common Fields topic.
Orifice Data
Database Table Name: hw_orifice
|
Field Name |
Description |
Database Field |
Size |
Precision |
Default |
Error Lower Limit |
Error Upper Limit |
Warning Lower Limit |
Warning Upper Limit |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
US node ID |
The ID of the upstream node for this orifice. An existing node ID can be selected from the dropdown. This makes up the first part of the link reference. |
us_node_id |
Text |
64 |
|
0 |
|
|
|
|
|
|
DS node ID |
The ID of the downstream node for this orifice. An existing node ID can be selected from the dropdown. |
ds_node_id |
Text |
64 |
|
0 |
|
|
|
|
|
|
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 |
|
|
|
|
|
Link type |
The sub-type of orifice can be set to:
|
link_type |
Text |
6 |
|
0 |
ORIFIC |
|
|
|
|
|
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 |
|
|
|
|
|
|
System type |
The system type can be selected from the dropdown. See System Type for more information. |
system_type |
Text |
10 |
|
0 |
Other |
|
|
|
|
|
Branch ID |
Identifies which long section the link is associated with. Can be set manually or automatically (see Defining Branches topic for more information). |
branch_id |
Long Integer |
|
|
0 |
|
0 |
|
|
|
|
US settlement efficiency (%) |
Relevant to Water Quality Simulations only.
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 |
|
|
|
DS settlement efficiency (%) |
Relevant to Water Quality Simulations only.
|
ds_settlement_eff |
Long Integer |
|
|
0 |
0 |
0 |
100 |
|
|
|
Invert level |
The level at which the orifice comes into operation. There is no default value for this field, the valid range is -99.9 to 999.9
|
invert |
Double |
|
Z |
3 |
|
-9999 |
9999 |
|
6000 |
|
Discharge coefficient |
This is the coefficient for the orifice flow equations. The discharge theory for an orifice predicts a typical velocity and concentration coefficient to be 1.0, which is the default value. The valid range is 0.01 to 999.9. Values typically range between 0.2 and 3.0 |
discharge_coeff |
Double |
|
|
2 |
1 |
0.01 |
|
|
|
|
Secondary discharge coefficient |
This applies when the depth of water is less than the diameter of the orifice, and weir equations apply. The default is the primary discharge coefficient for an orifice with its Opening type not set or set to Side. For an orifice with its Opening type set to Bottom, default for the Secondary discharge coefficient is 0.587. |
secondary_discharge_coeff |
Double |
|
|
2 |
0.587 (only if Opening type set to Bottom) |
0.01 |
|
|
|
|
Diameter |
Diameter of circular orifice. You should use the diameter of equivalent area for non-circular orifices. There is no default for this field; the valid range is 0 to 999.9 |
diameter |
Double |
|
L |
3 |
|
0.0 |
|
0.01 |
|
|
Limiting discharge |
The maximum discharge from upstream to downstream allowed through the orifice. The valid range is 0 to 999.9. If the value is greater than zero, this will be the maximum positive flow allowed through the orifice. For variable discharge orifice controls (Vldorf) this value is used for the initial limiting discharge. The default value is zero. A value of zero, or a blank field, means no restriction on maximum discharge for an Orific type of orifice. For a Vldorf type of orifice, a limit of zero is imposed when the Limiting discharge is set to 0. |
limiting_discharge |
Double |
|
Q |
3 |
|
0 |
|
|
|
|
Opening type |
The type of opening can be set to:
|
opening_type |
Text |
10 |
Side |
||||||
|
Minimum flow |
Displayed when Link type set to Vldorf. The minimum limiting discharge for the orifice. |
minimum_flow |
Double |
|
Q |
3 |
0 |
0 |
|
|
|
|
Maximum flow |
Displayed when Link type set to Vldorf. The maximum limiting discharge for the orifice. |
maximum_flow |
Double |
|
Q |
3 |
999 |
0 |
|
|
|
|
Positive change in flow |
Displayed when Link type set to Vldorf. The rate at which the limiting discharge for the orifice increases. The value must be greater than zero. This applies to RTC controlled orifice discharge rates. Flow data from TVD connectors will be applied directly to the orifice. |
positive_change_in_flow |
Double |
|
DQ |
5 |
|
0.000001 |
|
|
|
|
Negative change in flow |
Displayed when Link type set to Vldorf. The rate at which the limiting discharge for the orifice decreases. The value must be greater than zero. This applies to RTC controlled orifice discharge rates. Flow data from TVD connectors will be applied directly to the orifice. |
negative_change_in_flow |
Double |
|
DQ |
5 |
|
0.000001 |
|
|
|
|
Threshold |
Displayed when Link type set to Vldorf. The minimum change in limiting discharge that the software will implement. Any smaller change will be ignored. This prevents oscillation. |
threshold |
Double |
|
Q |
3 |
0 |
0 |
|
|
|
|
Points |
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 |
|
|
|
|
|
|
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 |
