Natural Gas UDCs
The following tables describe the input and output UDC mappings that the Line Pack driver sets for each pack segment calculation for natural gas. UDCs are configured on the UDC Map page of the device editor and must be configured for every pack segment. Any UDCs not defined for the optional outputs will not be set and will not generate any warnings.
The UDCs listed with the Last Segment Input: prefix indicate the points that are set for each pack segment and used as inputs to the Line Pack calculation. These points will hold the last good value of the specified input. See Calculation Inputs for more information.
See the following subsections for more information:
Required Input UDCs
The following table describes the point record configurations required for Line Pack. These UDCs must be configured for the facility of every pack sub-segment and for any pack segments that have no pack sub-segments.
| Point Description | Description | Point Type | Units |
|---|---|---|---|
|
Sub-Segment Status |
The status of the pack sub-segment. This value is configurable on the System Settings page. |
Enum |
N/A |
|
Sub-Segment Volume |
The pipe volume of the pack sub-segment. |
Analog |
MCF |
|
Sub-Segment Length |
The pipe length of the pack sub-segment. |
Analog |
mile |
|
Sub-Segment Diameter |
The pipe diameter of the pack sub-segment. |
Analog |
inch |
Required Output UDCs
The bulk of the UDCs in the following table are used for writing out the values of inputs used in the Line Pack calculation.
| Value | Description | Point Type | Units |
|---|---|---|---|
|
Last Segment Input: Inlet Temperature |
Indicates the input used in the line pack calculation for the upstream temperature. |
Analog |
F |
|
Last Segment Input: Outlet Temperature |
Indicates the input used in the line pack calculation for the downstream temperature. |
Analog |
F |
|
Last Segment Input: Temperature (Ordinal) |
Indicates the input used in the line pack calculation for the temperature ordinal. See note about ordinalized points. |
Analog |
F |
|
Last Segment Input: Inlet Press |
Indicates the input used in the line pack calculation for the upstream pressure. |
Analog |
psig |
|
Last Segment Input: Outlet Pressure |
Indicates the input used in the line pack calculation for the downstream pressure. |
Analog |
psig |
|
Last Segment Input: Pressure (Ordinal) |
Indicates the input used in the line pack calculation for the pressure ordinal. See note about ordinalized points. |
Analog |
psig |
|
Last Segment Input: Atmospheric Pressure |
Indicates the input used in the line pack calculation for the atmospheric pressure. |
Analog |
psi |
|
Last Segment Input: Segment Volume |
Indicates the input used in the line pack calculation for the segment volume. |
Analog |
MCF |
|
Last Segment Input: Correction Factor |
Indicates the input used in the line pack calculation for the volume correction factor. |
Analog |
N/A |
|
Last Segment Input: Nitrogen |
Indicates the input used in the line pack calculation for nitrogen. |
Analog |
% mole fraction |
|
Last Segment Input: Carbon Dioxide |
Indicates the input used in the line pack calculation for carbon dioxide. |
Analog |
% mole fraction |
|
Last Segment Input: Hydrogen |
Indicates the input used in the line pack calculation for hydrogen. |
Analog |
% mole fraction |
|
Last Segment Input: Carbon Monoxide |
Indicates the input used in the line pack calculation for carbon monoxide. |
Analog |
% mole fraction |
|
Last Segment Input: Methane |
Indicates the input used in the line pack calculation for methane. Note: Methane is required only if the NX-19 Supercompressibility formula is selected. |
Analog |
% mole fraction |
|
Last Segment Input: Specific Gravity |
Indicates the input used in the line pack calculation for specific gravity. |
Analog |
N/A |
|
Last Segment Input: Base Temp |
Indicates the input used in the line pack calculation for the base temperature. See System inputs for more information. |
Analog |
R |
|
Last Segment Input: Base Pressure |
Indicates the input used in the line pack calculation for the base pressure. See System inputs for more information. |
Analog |
psia |
|
Last Segment Input: Supercompressibility |
Indicates the input used in the line pack calculation for the supercompressibility factor. |
Analog |
N/A |
|
All Sub-Segments in Service |
Indicates if all sub-segments are in service. Options are NO or YES. |
Enum |
N/A |
|
Pack: Current |
Indicates the current pack |
Analog |
|
|
Pack: Mass Imbalance |
Indicates the flow rate at which the pipeline material is lost in terms of mass. Note: Requires that Mass Balance is enabled. See Configuring Mass Balance for more information about how this is calculated. |
Analog |
lb/S |
|
Last Segment Calc: Pack Mass |
Indicates the calculated intermediate value for mass. Note: Requires that Mass Balance is enabled. See Configuring Mass Balance for more information about how this is calculated. |
Analog |
lb |
|
Last Segment Calc: Total Inlet Flow Mass |
Indicates the calculated value for the upstream (inlet) mass flow rate. Note: Requires that Mass Balance is enabled. See Configuring Mass Balance for more information about how this is calculated. |
Analog |
lb/S |
|
Last Segment Calc: Total Outlet Flow Mass |
Indicates the calculated value for the downstream (outlet) mass flow rate. Note: Requires that Mass Balance is enabled. See Configuring Mass Balance for more information about how this is calculated. |
Analog |
lb/S |
Optional Output UDCs
Optional output values will not be calculated if the UDC is not configured (and no warning will be generated).
| Value | Description | Point Type | Units |
|---|---|---|---|
|
Last Segment Calc: Avg Temp |
Indicates the calculated intermediate value for average temperature. |
Analog |
R |
|
Last Segment Calc: Avg Pressure |
Indicates the calculated intermediate value for average pressure. |
Analog |
psia |
|
Last Segment Calc: Total Inlet Flow Volume |
Indicates the calculated value for the upstream (inlet) volume flow rate. Note: Optional if Mass Balance is enabled. |
Analog |
CFS |
|
Last Segment Calc: Total Outlet Flow Volume |
Indicates the calculated value for the downstream (outlet) volume flow rate. Note: Optional if Mass Balance is enabled. |
Analog |
CFS |
|
Last Segment Calc: Calculated Standard Density |
Indicates the calculated intermediate value for density at standard conditions. Note: Optional if Mass Balance is enabled. |
Analog |
lb/ft³ |
|
Last Segment Calc: Calculated Average Density |
Indicates the calculated intermediate value for density at pipeline segment average conditions. Note: Optional if Mass Balance is enabled. Note: This value can be selected as the segment average density when calculating Volume flow rate for Volume Imbalance or Volume Balance. |
Analog |
lb/ft³ |
|
Last Segment Input: Energy Content |
Indicates the input used in the line pack calculation for the energy content. |
Analog |
BTU/MCF |
|
Last Segment Input: MAOP |
Indicates the input used in the line pack calculation for the maximum allowed operating pressure (MAOP). |
Analog |
psig |
|
Pack: Last Hour |
Indicates the pack |
Analog |
|
|
Pack: Last Day |
Indicates the pack |
Analog |
|
|
Pack: Last Month |
Indicates the pack |
Analog |
|
|
Pack: Delta Last Hour * |
Indicates the change in pack Note: Requires UDC Pack: Delta Current Hour to be configured. |
Analog |
|
|
Pack: Delta Last Day * |
Indicates the change in pack Note: Requires UDC Pack: Delta Current Day to be configured. |
Analog |
|
|
Pack: Delta Current Hour * |
Indicates the change in pack Note: Requires UDC Pack: Last Hour to be configured. |
Analog |
|
|
Pack: Delta Current Day * |
Indicates the change in pack Note: Requires UDC Pack: Last Day to be configured. |
Analog |
|
|
Pack: Avg Delta Last Hour * |
Indicates the change in average pack Note: Requires UDC Pack: Last Hour to be configured. |
Analog |
|
|
Pack: Minimum Current Month |
Indicates the minimum pack |
Analog |
|
|
Pack: Minimum Current Day |
Indicates the minimum pack |
Analog |
|
|
Pack: Minimum Current Hour |
Indicates the minimum pack |
Analog |
|
|
Pack: Minimum Last Month * |
Indicates the minimum pack Note: Requires UDC Pack: Minimum Current Month to be configured. |
Analog |
|
|
Pack: Minimum Last Day * |
Indicates the minimum pack Note: Requires UDC Pack: Minimum Current Day to be configured. |
Analog |
|
|
Pack: Minimum Last Hour * |
Indicates the minimum pack Note: Requires UDC Pack: Minimum Current Hour to be configured. |
Analog |
|
|
Pack: Maximum Current Month |
Indicates the maximum pack |
Analog |
|
|
Pack: Maximum Current Day |
Indicates the maximum pack |
Analog |
|
|
Pack: Maximum Current Hour |
Indicates the maximum pack |
Analog |
|
|
Pack: Maximum Last Month * |
Indicates the maximum pack Note: Requires UDC Pack: Maximum Current Month to be configured. |
Analog |
|
|
Pack: Maximum Last Day * |
Indicates the maximum pack Note: Requires UDC Pack: Maximum Current Day to be configured. |
Analog |
|
|
Pack: Maximum Last Hour * |
Indicates the maximum pack Note: Requires UDC Pack: Maximum Current Hour to be configured. |
Analog |
|
|
Pack: Average Current Month |
Indicates the average pack |
Analog |
|
|
Pack: Average Current Day |
Indicates the average pack |
Analog |
|
|
Pack: Average Current Hour |
Indicates the average pack |
Analog |
|
|
Pack: Average Last Month * |
Indicates the average pack Note: Requires UDC Pack: Average Current Month to be configured. |
Analog |
|
|
Pack: Average Last Day * |
Indicates the average pack Note: Requires UDC Pack: Average Current Day to be configured. |
Analog |
|
|
Pack: Average Last Hour * |
Indicates the average pack Note: Requires UDC Pack: Average Current Hour to be configured. |
Analog |
|
|
Pack: Mass Balance |
Indicates the flow rate at which the pipeline material is gained in terms of mass. This is the negative of Pack: Mass Imbalance. Note: See Configuring Mass Balance for more information about how this is calculated. |
Analog |
lb/S |
|
Pack: Volume Imbalance |
Indicates the flow rate at which the pipeline material is lost in terms of standard volume. Note: See Configuring Mass Balance for more information about how this is calculated. |
Analog |
CFS |
|
Pack: Volume Balance |
Indicates the flow rate at which the pipeline material is gained in terms of standard volume. This is the negative of Pack: Volume Imbalance. Note: See Configuring Mass Balance for more information about how this is calculated. |
Analog |
CFS |
|
Pack: Current (Energy) |
Indicates the current pack volume converted to energy content. |
Analog |
BTU |
|
Pack: Delta Last Calc |
Indicates the change in line pack volume calculated for a segment as a rate over the time period since the previous line pack volume was calculated. This value is useful when viewed alongside the sum of input rates, output rates, and (im)balance values. |
Analog |
CFS |
|
Pack: Delta Last Calc (Mass) |
Indicates the change in line pack mass calculated for a segment as a rate over the time period since the previous line pack mass was calculated. This value is useful when viewed alongside the sum of input rates, output rates, and (im)balance values. Note: For natural gas, this mass value will only be available when Mass Balance is enabled. See Configuring Mass Balance for more information. |
Analog |
lb/S |
|
MAOP Pack: Current |
Indicates the current pack |
Analog |
|
|
MAOP Pack: Current (Energy) |
Indicates the current pack volume at the maximum allowed operating pressure (MAOP) converted to energy content. |
Analog |
BTU |
* Denotes that the calculation of this UDC is dependent on the configuration of another UDC.
